Trigeminal neuralgia

Trigeminal neuralgia - FACIAL PAIN

1. Trigeminal neuralgia BY : Dr. PRUTHVI RAJ . S JUNIOR RESIDENT ENT-HNS

2. CONTENTS ANATOMY OF TRIGEMINAL NERVE TRIGEMINAL NEURALGIA – DEFINITION HISTORY EPIDEMIOLOGY ETIOLOGY/ PREDISPOSING FACTORS TYPES CLINICAL FEATURES DIAGNOSIS TREATMENT

3. TRIGEMINAL NERVE Largest cranial nerve Sensory AND Motor

4. Gross anatomy The  trigeminal nerve is the largest and most complex of the 12 cranial nerves . It supplies sensations to the face, mucous membranes, and other structures of the head. It is the motor nerve for the muscles of mastication and contains proprioceptive fibers . It exits the brain by a large sensory root and a smaller motor root coming out of the pons at its junction with the middle cerebral peduncle . It passes laterally to join the gasserian (semilunar) ganglion in the Meckel cave.

5. nuclei The sensory nucleus, located in the pons, is quite extensive. It receives sensations from the main 3 branches of the  trigeminal . The ophthalmic division is in the lower part of the nucleus, and the mandibular branch is in the upper part . The large rostral head is the main sensory nucleus . The caudal tapered part is the spinal tract, which is continuous with substantia gelatinosa of Rolando in the spinal cord. The spinal tract is the sensory nucleus, primarily for pain and temperature. The main sensory nucleus serves mostly for discrimination sense.   The motor nucleus is ventromedial to the sensory nucleus. It lies near the lateral angle of the fourth ventricle in the rostral part of the pons. The mesencephalic nucleus is in the midbrain and receives proprioceptive fibers from all muscles of mastication.

6. connections The main sensory nucleus receives its afferents (as the sensory root) from the semilunar (trigeminal) ganglion through the lateral part of the pons ventral surface. Its axons cross to the other side, ascending to the thalamic nuclei to relay in the postcentral cerebral cortex. The descending sensory fibers from the semilunar ganglion course through the pons and medulla in the spinal tract of CN V to end in the nuclei of this tract (as far as the second cervical segment). The sensory nucleus of CN V is connected to other motor nuclei of the pons and medulla. In addition, the descending sensory spinal tract receives somatic sensory fibers from CNs VII, IX, and X . The proprioceptive fibers of CN V arise from the muscles of mastication . They terminate in the mesencephalic nucleus. This nucleus has connections to the motor nucleus of CN V.

7. The motor nucleus of CN V receives cortical fibers for voluntary control of the muscles of mastication. The axons emerge anterior to the sensory root from the lateral surface of the pons. This motor root joins the semilunar ganglion together with the sensory root . The semilunar ( gasserian or trigeminal) ganglion is the great sensory ganglion of CN V. It contains the sensory cell bodies of the 3 branches of the trigeminal nerve (the ophthalmic, mandibular, and maxillary divisions). The ophthalmic and maxillary nerves are purely sensory. The mandibular nerve has sensory and motor functions . The gasserian ganglion lies in a depression on the petrous apex , within a dural fold called the Meckel cave . The sensory roots of the 3 branches of CN V are received anteriorly. They then pass from the posterior aspect of the ganglion to the pons. The motor root passes under the ganglion to join the sensory division of the mandibular nerve and exits the skull through foramen ovale . The carotid plexus contributes sympathetic fibers to the gasserian ganglion.

8. COMPONENTS FUNCTION CENTRAL CONNECTIONS CELL BODIES PERIPHERAL DISTRIBUTION Afferent general somatic General sensibility Sensory nucleus V Gasserian ganglion Sensory branches of the ophthalmic, maxillary, and mandibular nerves to skin, mucous membranes of the face and head Efferent special visceral Mastication Motor nucleus V Motor nucleus V Branches to temporalis, masseter, pterygoids, mylohyoid, tensor tympani, and palati Afferent proprioceptive Muscular sensibility Mesencephalic nucleus V Mesencephalic nucleus V Sensory endings in muscles of mastication Summary of the Components, Function, Central Connections, Cell Bodies, and Peripheral Distribution of CN V

9. TYPE FUNCTION PATHWAY Branchial motor Motor to muscles of mastication CN V innervates the muscles of mastication, mylohyoid, tensor tympani, tensor veli palate, anterior belly of digastric General sensory Sensory from surface of head and neck, sinuses, meninges and TM The Gasserian ganglion receives the ophthalmic, maxillary and mandibular divisions of CN V and sympathetic fibers from the carotid plexus and sends branches to the dura. Summary of the Types of Fibers , Function, and Pathways of the Trigeminal Nerve

10. Branches of the Trigeminal Nerve The ophthalmic, maxillary , and mandibular branches of the trigeminal nerve leave the skull through 3 separate foramina: the superior orbital fissure, the foramen rotundum , and the foramen ovale , respectively.

11. The ophthalmic nerve The ophthalmic nerve is the first branch of the trigeminal nerve. It arises from the convex surface of the gasserian ganglion, in the dura of the lateral wall of the cavernous venous sinus under CN IV and above the maxillary nerve.

12. The ophthalmic nerve carries sensory information from the scalp and forehead, the upper eyelid, the conjunctiva and cornea of the eye, the nose (including the tip of the nose, except alae nasi ), the nasal mucosa, the frontal sinuses, and parts of the meninges (the dura and blood vessels ). The ophthalmic nerve receives sympathetic filaments from the cavernous sinus and communicating branches from CN III and IV. Just before it exits the skull through the superior orbital fissure, it gives off a dural branch , and then divides into 3 branches: the frontal, lacrimal, and nasociliary .

13. Frontal nerve This is the largest branch of the ophthalmic nerve. It passes in the lateral part of the superior orbital fissure, below the lacrimal nerve and above CN IV, between the periorbita and levator palpebrae superioris . It divides in the middle of the orbit into the supraorbital (larger branch) and supratrochlear nerves.

14. The supraorbital nerve exits the skull through the supraorbital notch (or foramen). It supplies the upper lid and then turns superiorly under the frontalis muscle to supply the scalp (via lateral and medial branches) as far posteriorly as the lambdoid suture . The supratrochlear nerve exits the medial orbit and gives branches to the conjunctiva and the skin of the upper lid, as well as to the lower and medial parts of the forehead. The branch to the frontal sinus pierces it in the supraorbital notch to supply the frontal sinus mucosa.

15. LACRIMAL NERVE : The lacrimal nerve arises in the narrow, lateral part of the superior orbital fissure and courses between the lateral rectus and the periorbita . It supplies the lacrimal gland, conjunctiva, and upper lid . In the orbit, it receives a communication from the zygomatic branch of the maxillary nerve . This represents postganglionic parasympathetic secretory fibers from the sphenopalatine ganglion to the lacrimal gland. The preganglionic fibers reach the ganglion via the greater petrosal and vidian nerves from CN VII. NASOCILIARY NERVE : After passing through the superior orbital fissure, the nasociliary nerve gives origin to the anterior ethmoid nerve that passes to the anterior ethmoid foramen lateral to the crista galli , to supply the fontal and anterior ethmoid sinuses. After dropping in the nose, it supplies the anterior part of the septum and lateral nasal wall. After emerging from the nose as the external nasal nerve , it supplies the skin of the nasal tip. The nasociliary nerve gives a branch to the ciliary ganglion that passes without synapsing to the cornea, iris, and ciliary body. The posterior ethmoid nerves are given off before the anterior ethmoid and supply the posterior ethmoid and sphenoid sinuses. The nasociliary nerve gives off 2-3 long ciliary nerves that enter the globe with the short ciliary nerves of the ciliary ganglion.

16. The Ophthalmic Nerve Branches and Distribution NERVE BRANCHES DISTRIBUTION Frontal nerve Supraorbital nerve    Upper lid , frontalis muscle, scalp  Supratrochlear nerve  Conjunctiva, upper lid, forehead  Lacrimal nerve Receives branch from the zygomatic nerve of the maxillary Lacrimal gland, conjunctiva, upper lid Nasociliary nerve Anterior ethmoid nerve  Frontal, anterior, ethmoid sinuses  Anterior septum, nasal wall  Branches to ciliary ganglion  Cornea, iris, ciliary body Posterior ethmoid nerve  Posterior ethmoid & sphenoid sinuses  2-3 long ciliary nerves  Eye

17. Maxillary nerve The maxillary nerve carries sensory information from the lower eyelid and cheek, the nares and upper lip, the upper teeth and gums, the nasal mucosa, the palate and roof of the pharynx, the maxillary, ethmoid and sphenoid sinuses, and parts of the meninges. The maxillary nerve is divided into 3 branches: the zygomatic, pterygopalatine (or sphenopalatine), and posterior superior alveolar nerves.

18. As it leaves the semilunar ganglion, the maxillary nerve passes through the dura of the lateral wall of the cavernous sinus. It exits the skull via the foramen rotundum and crosses the pterygopalatine fossa to enter the orbit through the inferior orbital fissure , where it becomes the infraorbital nerve . Before entering the foramen, it gives off a dural branch (middle meningeal nerve). The zygomatic, pterygopalatine (or sphenopalatine) and posterior superior alveolar branches are given off in the pterygopalatine fossa. The zygomatic branch divides into the zygomaticotemporal and zygomaticofacial nerves. In the lateral wall of the orbit, it gives off a branch to the lacrimal nerve, which carries postganglionic fibers from the sphenopalatine ganglion for lacrimation. The zygomaticofacial is inferiorly situated and supplies the skin of the cheek. The pterygopalatine (or sphenopalatine) nerves are 2 nerves that unite the sphenopalatine ganglion to the maxillary nerve. They transmit afferent sensations from the nose, palate, and pharynx. They also carry parasympathetic fibers to the lacrimal nerve that go to the lacrimal gland. These preganglionic fibers are derived from CN VII via the greater petrosal and vidian nerves.

19. NERVE BRANCHES DISTRIBUTION Middle meningeal nerve Dura Zygomatic nerve Zygomatico -temporal Lacrimal gland ,Forehead , Cheek  Zygomatico -facial  Pterygopalatine nerve 2 branches unite sphenopalatine ganglion and maxillary nerve Nasal cavity, pharynx, palate  Greater palatine nerve  Soft and hard palate   Posterior superior nasal nerve  Superior, middle turbinate, septum  Pharyngeal  Nasopharynx  Posterior superior alveolar nerve  Middle, anterior, superior alveolar, and nasal nerve Gums, posterior cheek, teeth (canine, incisors, premolar), nasal floor  The Maxillary Nerve Branches and Distribution.

20. MANDIBULAR NERVE The mandibular nerve is the largest branch of the trigeminal nerve. It has mixed sensory and motor fibers .

21. The mandibular nerve carries sensory information from the lower lip, the lower teeth, gums, the chin and jaw ( except the angle of the mandible, which is supplied by C2-C3 ), parts of the external ear, and parts of the meninges. The mandibular nerve carries touch/position and pain/temperature sensations from the mouth. It does not carry taste sensation (the chorda tympani is responsible for taste), but one of its branches, the lingual nerve , carries multiple types of nerve fibers that do not originate in the mandibular nerve . Motor branches of the trigeminal nerve are distributed in the mandibular nerve. These fibers originate in the motor nucleus of the fifth nerve, which is located near the main trigeminal nucleus in the pons.

22. The mandibular nerve has the following 9 branches: Recurrent meningeal nerve - This nerve enters the skull via the foramen spinosum with the meningeal artery. Medial pterygoid nerve - After passing through the otic ganglion without synapsing, this nerve supplies the medial pterygoid, tensor veli palatini , and tensor tympani muscles. Masseteric nerve - This nerve passes through the mandibular notch to innervate the masseter muscle and temporomandibular joint . Deep temporal nerves - The anterior and posterior branches supply the temporal muscle. Lateral pterygoid nerve Buccal nerve - This nerve divides into the temporal and buccinator branches. Auriculotemporal nerve - This nerve begins as 2 roots that encircle the middle meningeal artery, then forms a single trunk medial to the neck of the mandible; it emerges superficially between the ear and the mandibular condyle deep to the parotid gland and ends in 2 superficial temporal branches (for autonomic supply to the parotid gland).

23. Lingual nerve - This nerve runs parallel to the inferior alveolar nerve, is joined by the chorda tympani nerve of the facial nerve (CN VII) near the internal maxillary artery, courses forward between the hyoglossus muscle and the deep part of the submandibular gland and as it passes forward, crosses the submandibular (Wharton) duct; the lingual nerve could be injured in this location during surgery on the floor of mouth or during excision of the submandibular gland. Inferior alveolar nerve - This nerve accompanies the inferior alveolar artery in the mandibular foramen and courses into the mandibular canal to exit through the mental foramen.

24. NERVE BRANCHES DISTRIBUTION Recurrent meningeal Dura Medial pterygoid Medial pterygoid, tensor veli palatini , tensor tympani muscles Masseteric Masseter muscle, temporomandibular joint Deep temporal Temporalis muscle Lateral pterygoid Lateral pterygoid muscle Buccal Temporal nerve (upper)  Skin of cheek, mucous membrane of mouth, and gingiva Buccinator nerve (lower) Mandibular Nerve Branches and Distribution

25. NERVE BRANCHES DISTRIBUTION Auriculotemporal Communication with facial nerve, and otic ganglion, Parasympathetic and sympathetic supply to the parotid gland, after relay in the otic ganglion Articular nerve  Parotid gland  Lingual Communicates with CN VII via chorda tympani  Inferior alveolar Mylohyoid Mylohyoid, anterior, belly of digastric, molars, premolars, canine, incisors lower lip, and chin Dental Incisive Mental

26. COMPONENTS FUNCTIONS OPENING IN SKULL OPHTHALMIC (SENSORY) Cornea, skin of forehead, scalp, eyelids, and nose; also mucous membrane of paranasal sinuses and nasal cavity. Superior orbital fissure MAXILLARY (SENSORY) Skin of face over maxilla and the upper lip; teeth of upper jaw; mucous membrane of nose, the maxillary air sinus, and palate. Foramen rotundum MANDIBULAR (SENSORY) Skin of cheek, skin over mandible, lower lip, and side of head; teeth of lower jaw and temporomandibular joint; mucous membrane of mouth and anterior two thirds of tongue . MANDIBULAR (MOTOR) Muscles of mastication, mylohyoid, anterior belly of digastric, tensor veli palatini , and tensor tympani. Foramen ovale

27. p arasympathetic ganglia Four small parasympathetic (accessory) ganglia are associated anatomically (but not functionally) with the branches of the trigeminal nerve.   They are as follows : Ciliary ganglion Sphenopalatine (or pterygopalatine) ganglion Otic ganglion Submandibular ganglion

28. The ciliary ganglion is associated with the ophthalmic nerve. It is the size of a pinhead and has the following 3 roots: The parasympathetic root from the nerve to inferior oblique (CN III) from Edinger Westphal nucleus and caudal central nucleus to supply the sphincter papillae and ciliary muscles. Sympathetic root from the nasociliary nerve to dilator papillae muscle of the eye. Sensory root from the nasociliary nerve to the cornea. The sphenopalatine ganglion is associated with the maxillary nerve. It receives its parasympathetic fibers from CN VII . The otic and submandibular ganglia are associated with the mandibular nerve. They receive parasympathetic fibers from CNs IX and VII, respectively.

29. Autonomic supply to the salivary glands SUBMANDIBULAR GLAND : Parasympathetic fibers arise from the superior salivary nucleus in the pons. Fibers pass through the facial nerve to the chorda tympani and then to the lingual nerve. Synapsing occurs in the submandibular ganglion and from there to the submandibular salivary gland. Sympathetic supply is from the plexus around the facial artery.

30. PAROTID GLAND : Parasympathetic fibers arise from the inferior salivary nucleus in the medulla oblongata, pass through the glossopharyngeal nerve (CN IX), and then travel through its tympanic branch to the tympanic plexus ( Jacobson nerve ). They emerge from the middle ear through a hiatus on the anterior surface of the petrous temporal bone, as the lesser superficial petrosal nerve . This nerve passes via the foramen ovale to the otic ganglion (which hangs from the medial side of the mandibular nerve ). Relay occurs in the otic ganglion, and from there it is distributed to the parotid gland via the auriculotemporal nerve . Sympathetic fibers are from the superior cervical ganglion; they go to the plexus around the meningeal artery and from there to the auriculotemporal nerve, which distributes them to the parotid salivary gland.

31. EXAMINATION SENSORY MOTOR

32. TRIGEMINAL REFLEXES CORNEAL REFLEX LACRIMATION REFLEX JAW JERK OCULO-CARDIAC REFLEX

33. CORNEAL REFLEX

34. Tactile Stimulation of cornea Short Ciliary nerve Nasociliary Nerve Sensory nucleus of V CN Trigeminal ganglion Ophthalmic Nerve Facial nerve Nucleus Facial nerve Temporal & Zygomatic branch Orbicularis Oculi b/l Blinking INTERNEURONS

35. LACRIMATION REFLEX

36. JAW JERK Exaggerated in upper motor neuron lesions .

37. OCULO-CARDIAC REFLEX

38. Oculo -cardiac reflex In 1908, Aschner described a decrease in heart rate as a consequence of applying pressure directly to the eyeball. This phenomenon would eventually be termed “the oculocardiac reflex” and is defined clinically as a decrease in heart rate by 10% following pressure to the globe or traction of the ocular muscles.  AFFERENT LIMB : Trigeminal Nerve (ciliary ganglion to ophthalmic division of trigeminal nerve to gasserian ganglion to the main trigeminal sensory nucleus). Also afferent tracts from maxillary and mandibular divisions of trigeminal nerve have been documented . EFFERENT LIMB : Vagus Nerve ( afferents synapse with visceral motor nucleus of vagus nerve located in the reticular formation and efferents travel to the heart and decrease output from the sinoatrial node).

39. TRIGGERING STIMULI : Triggered by traction on the extraocular muscles (especially medial rectus), direct pressure on the globe, ocular manipulation, ocular pain. Can also be triggered by retrobulbar block (pressure associated with local infiltration), ocular trauma, or manipulation of tissue in orbital apex after enucleation. MANIFESTATIONS : Most commonly leads to sinus bradycardia, but may also lead to junctional rhythm, ectopic beats, atrioventricular block, ventricular tachycardia, and asystole . RISK FACTORS : The incidence of the oculocardiac reflex decreases with age and tends to be more pronounced in young, healthy patients .

40. TREATMENT INTRAOPERATIVE : May occur during both local and general anesthesia . The retrobulbar block may prevent arrythmias by blocking the afferent limb, but may also stimulate the OCR with pressure of local injection. Notify the surgeon to stop orbital stimulation. Optimize oxygenation and ventilation. If arrythmia /bradycardia does not resolve consider atropine 20 mcg/kg IV (or glycopyrrolate ). POSTOPERATIVE : The OCR may occur as much as 1.5 hours after a retrobulbar block. Retrobulbar hemorrhage can result in delayed OCR as persistent bleeding gradually increases periocular pressure. Monitor carefully in the I CU if suspected retrobulbar hemorrhage .

41. • Trauma , tumors , aneurysms or meningeal infections will cause : Paralysis of muscles of mastication with deviation of mandible towards the site of lesion . Loss of soft tactile, thermal or painful sensations on the face Loss of corneal reflex • Trigeminal neuralgia : excruciating pain in the area of distribution; females more affected. Referred pain Mandibular nerve block Dental anesthesia ( Inferior Alveolar nerve block) Lingual nerve injury APPLIED ANATOMY

42. Trigeminal neuralgia The International Association for the study of pain (IASP) defines TN as sudden usually unilateral , severe , brief , stabbing and recurrent pains in the distribution of one or more branches of TN.

43. Historical perspectives Aretaeus of Cappadocia is credited with the first clinical description of TN. At the end of the first century he described a condition ( heterocrania ) where ‘‘spasm and distortion of the countenance (facial expression) take place .’’ Jujani , an 11th century Middle Eastern physician, also discussed a problem of unilateral facial pain with associated spasms and anxiety. He even suggested the pain resulted from ‘‘the proximity of the artery to the nerve.’’ The first adequate description of trigeminal neuralgia was given in 1671 by German physician, Johannes Laurentius Bausch , who suffered from a lightning like pain in the right face. He became unable to speak or eat properly and apparently succumbed to malnutrition. In 1677 John Locke , a noted American physician and philosopher, accurately identified the major clinical features of TN in the Countess of Northumberland. He correctly recognized that her facial pain was not caused by dental pathology but rather by neuralgia of the trigeminal nerve.

44. In 1756, André reported two cases of TN, which he termed tic douloureux . The term tic douloureux was used to imply contortions and grimaces accompanied by violent and unbearable pain. André believed that the cause was "vicious nervous liquids" that distressed the nerve and caused painful shocks. Using this reasoning, he followed the proposal of Maréchal (a contemporary surgeon) by applying caustic substances to the infraorbital nerve at the infraorbital foramen over a period of days until the nerve was destroyed. John Fothergill described trigeminal neuralgia as "a painful affection of the face”. He presented 14 cases of a painful affliction of the face. His description of TN has been considered an accurate and clear account. Given his meticulous description of the clinical symptoms, many thereafter referred to this condition as " Fothergill's disease”.

45. In 1779, John Hunter more clearly characterized the entity as a form of "nervous disorder" with reference to pain of the teeth, gums, or tongue where the disease "does not reside." One hundred fifty years later, the neurological surgeon Walter Dandy equated neurovascular compression of the trigeminal nerve with trigeminal neuralgia . In the early 20 th century , Oppenheim alluded to an association between multiple sclerosis (MS) & trigeminal neuralgia and Patrick commented on its familial incidence.

46. PATHOPHYSIOLOGY Symptoms result from ectopic generation of action potentials in pain-sensitive afferent fibers of the fifth cranial nerve root just before it enters the lateral surface of the pons. Compression or other pathology in the nerve leads to demyelination of large myelinated fibers that do not themselves carry pain sensation but become hyperexcitable and electrically coupled with smaller unmyelinated or poorly myelinated pain fibers in close proximity; this may explain why tactile stimuli, conveyed via the large myelinated fibers , can stimulate paroxysms of pain.

47. Compression of the trigeminal nerve root by a blood vessel, most often the superior cerebellar artery or on occasion a tortuous vein , is the source of trigeminal neuralgia in a substantial proportion of patients. In cases of vascular compression, age-related brain sagging and increased vascular thickness and tortuosity may explain the prevalence of trigeminal neuralgia in later life.

48. Pathophysiology : central cause versus peripheral cause In favour of a peripheral cause , following arguments were pointed : Space-occupying lesions, even distant from the nerve but distorting it, can provoke typical TN . Microvascular compression (distortion) of the trigeminal root as a cause of “idiopathic” TN is now well documented . Pathologic findings in patients with TN : vacuolated ganglion cells, segmental demyelination, juxtaposition of denuded axons . It is well recognized that damaged nerves can be the source of pain, which is attributed to several possible mechanisms : hyperexcitability of demyelinated nerve fibers , ectopic impulse generation, cross-talk between sensory channels, deafferentation and impaired segmental inhibition ( Burchiel , 1980 ; Sessle , 1991 ; Rappaport, 1994).

49. In favour of a central cause , following observations were pointed : Typical TN can be due to multiple sclerosis . Physiological observations on patients suffering from TN point to central mechanisms : spatial and temporal summation of the effects of stimulus, tendency of the attack to be self-maintained, refractory period after an attack, efficacy of antiepileptic drugs ( Kugelberg and Lindblom , 1959) . Experimental “models” of TN : application of certain substances into the trigeminal nucleus caudalis produces hypersensitivity of the face that resembles the TN trigger zone (King et al., 1956 ; Black, 1974 ; Sakai et al., 1979). A valid experimental model of TN is however still lacking.

50. epidemiology E stimated annual incidence of 4.5 per 100,000 individuals Middle-aged and elderly persons are affected primarily, and 60% of cases occur in women Onset is typically sudden , and bouts tend to persist for weeks or months before remitting spontaneously. Remissions may be long-lasting, but in most patients the disorder ultimately recurs

51. ETIOLOGY / PREDISPOSING FACTORS Idiopathic Heredity Compression of trigeminal nerve root is the most common cause of trigeminal neuralgia. The compression occurs usually within few millimeters of entering in to the pons. The primary demyelinating disorders can also lead to this condition . A few rare conditions that can cause trigeminal neuralgia are: Infiltration of nerve root (due to carcinomatous deposit within nerve root, gasserian ganglion and nerve ) Small infarcts or angiomas in the pons or medulla . Infiltration of gasserian ganglion or the nerve by a tumour or amyloid

52. Most widely accepted theory is that majority of cases of trigeminal neuralgia are caused by atherosclerotic blood vessel (usually the superior cerebellar artery) pressing on and grooving the root of trigeminal nerve. This pressure results in focal demyelinization and hyperexcitability of nerve fibers , which will then fire in response to light touch, resulting in brief episodes of intense pain . Jannetta in 1967 first recognized the focal compression of trigeminal nerve root as a major etiological factor for the trigeminal neuralgia. Now it is considered as an important cause of trigeminal neuralgia in 80-90% of cases. The part of nerve root that commonly compressed is actually within CNS tissue. There are following compressing lesions that can lead to TGN are : Vestibular schwannomas Meningiomas Epidermoid cyst etc

53. Primary demyelinating disorders : A well known complication of multiple sclerosis is TGN. The plaque of demyelination encompasses the root entry zone of trigeminal nerve in the pons. The compression of blood vessel may also contribute in the compression of root entry of trigeminal nerve in some patient with multiple sclerosis suffering from trigeminal neuralgia . Nondemyelinating lesions : Nakamura et al, Golby et al have reported some patients with trigeminal neuralgia who were suffering from angiomas and small infarcts within the brain stem. Familial trigeminal neuralgia : In 1979 Knuckey and Gubbay reported several individuals in three generations of family were suffering from trigeminal / glossopharyngeal neuralgia . Coffey et al reported a familial occurrence in trigeminal neuralgia. The patients were treated with percutaneous retrogasserian glycerol rhizolysis successfully.

54. Diabetes : Neuralgia anywhere in the body including the trigeminal neuralgia can also cause by diabetes. Diabetes causes the damage of tiny arteries that provide circulation to the nerves which lead to nerve fibers malfunctions and sometimes nerve loss. Infectious conditions : The trigeminal neuralgia can also manifest by infectious conditions cerebellopontine angle cysticercosis , pons abscess and cases of bacterial infections like Mycobacterium leprae , Secondary syphilis, Leptospirosis, Shigella etc. Stress : According to Beth Israel Medical Center Department of Pain Medicine and Palliative Care the trigeminal neuralgia can be caused by stress also. Stress leads to inflammation of blood vessel which can compress or irritate the trigeminal nerve. Patient having the trigeminal neuralgia with another cause, the severity of painful attacks can worsen by stress.

55. A typical initial manifestation that, in some patients, precedes the classic presentation of TN, was introduced by Symonds . He described a dull continuous, aching pain in the upper or lower jaw that later developed in to classic paroxysmal pain. This prodromal pain is termed as “pre-trigeminal neuralgia” by Mitchell . Descriptions of PTN have included pain that is mild to moderate in intensity, dull, aching, burning, throbbing, soreness of gums and toothache . Fromm GH et al reported 18 patients who subsequently developed typical trigeminal neuralgia experienced a prodromal pain termed “pre-trigeminal neuralgia.” The prodromal pain was described as a toothache or sinusitis-like pain lasting up to several hours, sometimes triggered by jaw movements or by drinking hot or cold liquids. Typical trigeminal neuralgia develops a few days to 12 years later, and in all cases affected the same division of the trigeminal nerve. Six additional patients experiencing what appeared to be pre-trigeminal neuralgia became pain-free when taking carbamazepine or baclofen . PRE - TRIGEMINAL NEURALGIA

56. CLASSIFICATION BASED ON ETIOLOGY : The international headache society (IHS) has classified trigeminal neuralgia in to two categories according to etiology : 1) Classical trigeminal neuralgia – In classical trigeminal neuralgia there is no cause of the symptoms can be identified other than vascular compression . 2) Symptomatic trigeminal neuralgia – Symptomatic trigeminal neuralgia has the same clinical criteria, but another underlying cause is responsible for the symptoms.

57. Based on symptoms : From symptomatic point of view the trigeminal neuralgia is classified in to following: Typical Trigeminal Neuralgia (Tic Douloureux ) Atypical trigeminal neuralgia

58. Typical Trigeminal Neuralgia (Tic Douloureux ) This is the most common form of TN, which has previously been termed Classical, Idiopathic TN . Nearly all cases of typical TN are caused by blood vessels compressing the trigeminal nerve root as it enters the brain stem; may be caused by arteries of veins, large or small, that may simply contact or indent the trigeminal nerve. Pulsation of vessels upon the trigeminal nerve root do not visibly damage the nerve. However, irritation from repeated pulsations may lead to changes of nerve function, and delivery of abnormal signals to the trigeminal nerve nucleus. Over time, this is thought to cause hyperactivity of the trigeminal nerve nucleus, resulting in the generation of TN pain. The superior cerebellar artery is the vessel most often responsible for neurovascular compression upon the trigeminal nerve root, although other arteries or veins may be the culprit vessels.

59. Atypical trigeminal neuralgia Persistent pain is usually burning or aching pain. Patients have bilateral pain more frequently than typical TN . Duration of paroxysms is often longer . Patients are generally younger than typical TN CAUSE : may be due to neural compression peripheral to the area where the root enters the brainstem but central to trigeminal ganglion .

60. Clinical features Recurring episodes of intense, short-lived spasms of pain of the lower portion of the face and the jaw. In most cases, pain is limited to one side of the face (unilateral). The pain has been compared to a series of " electrical shocks " followed by a steady dull ache. The pain often starts and stops rapidly . Intense pain usually lessens rapidly (usually within several seconds), but the following dull aching pain may persist for as much as one to two minutes. For many individuals, pain is completely gone in between episodes.

61. Some patients are sensitive in certain areas of face called trigger zone , which when touched cause an attack. These zones are usually near the nose, lips, eyes, ears or inside the mouth. Pain may be triggered by mild tactile stimuli including brushing one’s teeth, washing one’s face, shaving, drinking hot or cold drinks, chewing, talking, blowing one’s nose, a cool breeze, or a light touch to the face. Some episodes may occur without an apparent trigger ( spontaneously ). Consequently, episodes can occur repeatedly throughout the day. Episodes rarely occur during sleep. Attacks typically stop for a period of time and then return. Over time, the pain tends to grow worse with fewer pain-free periods.

62. Clinical features Trigeminal neuralgia is more common in maxillary & mandibular nerves distribution regions & very rarely, in the distribution of the ophthalmic division of the fifth nerve. The pain seldom lasts more than a few seconds or a minute or two but may be so intense that the patient winces, hence the term tic . An essential feature of trigeminal neuralgia is that objective signs of sensory loss cannot be demonstrated on examination.

63. DIFFERENTIAL DIAGNOSIS Trigeminal neuralgia must be distinguished from other causes of face and head pain and from pain arising from diseases of the jaw, teeth, or sinuses. Pain from migraine or cluster headache tends to be deep-seated and steady, unlike the superficial stabbing quality of trigeminal neuralgia ; Rarely , cluster headache is associated with trigeminal neuralgia, a syndrome known as cluster-tic . In temporal arteritis , superficial facial pain is present but is not typically shocklike , the patient frequently complains of myalgias and other systemic symptoms, and an elevated erythrocyte sedimentation rate (ESR) is usually present . When trigeminal neuralgia develops in a young adult or is bilateral, multiple sclerosis (MS) is a key consideration, and in such cases the cause is a demyelinating plaque at the root entry zone of the fifth nerve in the pons; often, evidence of facial sensory loss can be found on careful examination. Cases that are secondary to mass lesions — such as aneurysms, neurofibromas , acoustic schwannomas , or meningiomas — usually produce objective signs of sensory loss in the trigeminal nerve distribution (trigeminal neuropathy )

64. The diagnostic criteria of the International Headache Society (IHS) (1988) are as follows : (A) Paroxysmal attacks of facial pain which last a few seconds to less than two minutes. (B) Pain has at least 4 of the following characteristics: • Distribution along one or more divisions of the trigeminal nerve. • Sudden, intense, sharp, superficial, stabbing or burning in quality. • Pain intensity is severe. • Precipitation from trigger areas, or by certain activities such as eating, talking, washing the teeth or cleaning the face. • Between paroxysms the patient is entirely asymptomatic. (C) Attacks are stereotyped in the individual patient. (D) No neurological deficit and exclusion of other causes DIAGNOSIS - CLINICAL

65. In the second edition the diagnostic criteria for classical trigeminal neuralgia are as follows: A) Paroxysmal attacks of pain lasting from fraction of a second to two minutes, affecting one or more division of trigeminal nerve and fulfilling criteria B&C. B) Pain has at least one of the following characteristics: Intense, sharp, superficial or stabbing. Precipitated from trigger area or by trigger factor. C) Attacks are stereotype in the individual patients. D) There is no clinically evident neurological defect. E) Not attributed to another disorder

66. INVESTIGATIONS An ESR is indicated if temporal arteritis is suspected. In typical cases of trigeminal neuralgia, neuroimaging studies (MRI) are usually unnecessary but may be valuable if MS is a consideration or in assessing overlying vascular lesions in order to plan for decompression surgery. Sensory testing is not done routinely, but quantitative sensory testing (QST) and evoked potentials may play an important role in differentiating between symptomatic and idiopathic TN.

67. treatment Pharmacotherapy had little success in this condition until bergouignan’s discovery in 1942 that phenytoin was effective in preventing pain paroxysms. Soon following the introduction of carbamazepine for treatment of epilepsy , controlled trials showed its superiority over placebo in TGN . Since then anticonvulsants have been the mainstay of pharmacological treatment.

68. DRUG THERAPY Drug therapy with carbamazepine is effective in 50–75% of patients. Carbamazepine should be started as a single daily dose of 100 mg taken with food and increased gradually (by 100 mg daily in divided doses every 1–2 days) until substantial (>50%) pain relief is achieved. Most patients require a maintenance dose of 200 mg qid . Doses >1200 mg daily provide no additional benefit. Dizziness, imbalance, sedation, and rare cases of agranulocytosis are the most important side effects of carbamazepine. If treatment is effective, it is usually continued for 1 month and then tapered as tolerated. Oxcarbazepine (300–1200 mg bid) is an alternative to carbamazepine, has less bone marrow toxicity, and probably is equally efficacious. If these agents are not well tolerated or are ineffective, lamotrigine 400 mg daily or phenytoin , 300–400 mg daily, are other options. Baclofen may also be administered, either alone or in combination with an anticonvulsant. The initial dose is 5–10 mg tid , gradually increasing as needed to 20 mg qid .

69. SURGERY Surgical treatments are generally reserved for patients with debilitating pain refractory to an adequate trial of at least three drugs including CBZ in sufficient dosage. Surgery for TN is either destructive (ablative) , where the trigeminal nerve sensory function is intentionally destroyed, or non-destructive , where the trigeminal nerve is decompressed preserving its normal function. Gasserian ganglion percutaneous techniques are all destructive and include radiofrequency thermocoagulation (RFT), balloon compression (BC) and percutaneous glycerol rhizolysis (PGR ).

70. SURGERY MICROVASCULAR DECOMPRESSION GAMMA KNIFE RADIOSURGERY RADIOFREQUENCY THERMAL RHIZOTOMY

71. Microvascular decompression The most widely used surgical method currently is microvascular decompression to relieve pressure on the trigeminal nerve as it exits the pons. This procedure requires a suboccipital craniotomy . Based on data, this procedure appears to have a >70% efficacy rate and a low rate of pain recurrence in responders; the response is better for classic tic-like symptoms than for nonlancinating facial pains. High-resolution magnetic resonance angiography is useful preoperatively to visualize the relationships between the fifth cranial nerve root and nearby blood vessels.

72. Microvascular decompression achieves the most sustained pain relief with 90% of patients reporting initial pain relief and over 80% still pain free after 1 year, with 75% after 3 years and 73% after 5 years remaining pain free . The average mortality rate ranges from 0.2% to 0.5%, and up to 4% of patients suffer from major problems such as cerebrospinal fluid (CSF) leakage, infarcts or haematomas. The most common complications are aseptic meningitis (11%), sensory loss (7%) and hearing loss (10%) as long-term complications [ Cruccu et al. 2008; Gronseth et al. 2008 ]. In a small number of cases, there is perioperative damage to the eighth or seventh cranial nerves or to the cerebellum , or a postoperative CSF leak syndrome .

73. Gamma knife radiosurgery Gamma knife radiosurgery is also utilized for treatment and results in complete pain relief in more than two-thirds of patients and a low risk of persistent facial numbness. In gamma knife surgery , a focused beam of radiation is aimed at the trigeminal root in the posterior fossa. The response is sometimes long-lasting, but recurrent pain develops over 2–3 years in half of patients . Compared with surgical decompression, gamma knife surgery appears to be somewhat less effective but has few serious complications .

74. One year after gamma knife surgery, 69% of patients are pain free without additional medication. At 3 years, 52% are still pain free. The development of pain relief can be delayed (mean 1 month ). Side effects are sensory complications in 6% that may develop with a delay of up to 6 months, facial numbness in 9-37 % which improves over time and paresthesias in 6-13 % [ Cruccu et al. 2008; Gronseth et al. 2008]. Quality of life improves by 88% [ Zakrzewska et al. 1999]. The main disadvantage of gamma knife surgery is the treatment expense that limits widespread usage making it a reserve treatment option for patients that cannot undergo open surgery or have blood coagulation problems (e.g. are receiving warfarin).

75. radiofrequency thermal rhizotomy R adiofrequency thermal rhizotomy , creates a heat lesion of the trigeminal ( gasserian ) ganglion or nerve. It is used less often now than in the past. Short-term relief is experienced by >95% of patients; however, long-term studies indicate that pain recurs in up to one-third of treated patients . Postoperatively , partial numbness of the face is common, masseter (jaw) weakness may occur especially following bilateral procedures, and corneal denervation with secondary keratitis can follow rhizotomy for first-division trigeminal neuralgia.

76. After 1 year, 68-85 % of patients are still pain free, after 3 years this is reduced to 54-64 % and after 5 years only 50% of patients are still pain free following the procedure. The most common side effects are sensory loss (50%) which extremely decreases the quality of life [ Zakrzewska et al. 1999], dysesthesias (6%), anaesthesia dolorosa (4%), corneal numbness with risk of keratitis (4%). Gasserian ganglion therapies require short acting anesthetics , are primarily overnight minor procedures with extremely low mortality [ Cruccu et al. 2008; Gronseth et al. 2008].

77. Transcranial magnetic stimulation Repetitive transcranial magnetic stimulation ( rTMS ) is an emerging technology that introduces the possibility of assessing whether patients with trigeminal neuropathic pain will respond to direct epidural cortical stimulation by first measuring their response to a trial of non-invasive cortical stimulation. In a study of 24 TN patients given rTMS to the motor cortex at 20Hz daily for 5 days, pain ratings decreased by approximately 45% for 2 weeks [ Khedr et al. 2005 ]. In a different study of 12 patients with chronic intractable TN who had failed surgical treatment, 58% experienced a greater than 30% reduction in pain after receiving repetitive TMS [ Lefaucheur et al. 2004].

78. During a TMS procedure, a magnetic field generator, or "coil" is placed near the head of the person receiving the treatment . The coil produces small electric currents in the region of the brain just under the coil via electromagnetic induction. The coil is connected to a pulse generator, or stimulator, that delivers electric current to the coil . This electric field causes a change in the transmembrane current of the neuron, which leads to the depolarization or hyperpolarization of the neuron and the firing of an action potential .

79. Treatment of trigeminal neuralgia in multiple sclerosis The pharmacological treatment of TN in MS is similar to that of idiopathic TN. Central nervous system (CNS) demyelination renders some patients with MS more sensitive to cognitive and motor side effects, which might lead to an earlier decision for surgery in these patients. However , surgical outcomes are less predictable and less durable in MS, presumably due to unrelieved central pain mechanisms [ Athanasiou et al. 2005; Broggi et al. 2004]. Nevertheless , the possibility of additional nerve-vessel conflict in MS patients should be kept in mind.

80. Microvascular decompression is associated with a favourable response in approximately 50% of patients [ Monstad , 2007; Patwardhan et al. 2006; Cheng et al. 2005]. The major problem with microvascular decompression in this patient population is the observation that TN often occurs bilaterally and bilateral posterior fossa craniotomies entail a greater risk [Berk, 2001 ]. MS patients also have a considerably less-satisfactory long-term outcome following microvascular decompression, particularly when MRI finds demyelinating lesions in the brainstem trigeminal pathways of the painful side, indicating an ongoing role of central mechanisms [ Patwardhan et al. 2006; Berk, 2001].

81. ??????????? More recent investigations have focused mainly on treatment evaluation in long-term follow-up studies [ Kabatas et al. 2009; Little et al. 2008] and improvement of existing surgical techniques [ Kanpolat et al. 2008; Sindou et al. 2008; Tatli and Sindou , 2008 ]. Even though this has been the most active field of TN research over recent years, the vast majority of studies remain on a descriptive level making evidence-based comparison and recommendation difficult. The right timing for surgical intervention is yet to be determined [ Spatz et al. 2007]. Some TN experts suggest early surgical referral in patients who fail to respond to first-line medical therapy, while others request trialling of at least two different medical regimens including combination therapy before considering surgery. There is no supporting evidence for either of the two opinions. Referral for surgical intervention seems reasonable in TN patients refractory to medical therapy.

82. TRIGEMINAL NEUROPATHY SITE OF LESION CAUSES Nuclear (brainstem) lesions Multiple sclerosis, Stroke, Syringobulbia , Glioma, Lymphoma Preganglionic lesions Acoustic neuroma, Meningioma, Metastasis, Chronic meningitis, Cavernous carotid aneurysm Gasserian ganglion lesions Trigeminal neuroma, Herpes zoster, Infection (spread from otitis media or mastoiditis) Peripheral nerve lesions Nasopharyngeal carcinoma, Trauma, Guillain-Barré syndrome, Sjögren's syndrome, Collagen-vascular diseases, Sarcoidosis, Leprosy Drugs ( stilbamidine , trichloroethylene) Idiopathic trigeminal neuropathy

83. REFERENCES Harrison's Principles of Internal Medicine (19th Ed) Rahul Srivastava etal , Diagnostic criteria and management of trigeminal neuralgia: A review , Asian Pac. J. Health Sci., 2015; 2(1): 108-118 Scott brown’s otorhinolaryngology, head & neck surgery(7 TH edition ). Cummings otolaryngology & head & neck surgery (6 th edition). Gray’s anatomy (40 th edition ). http:// emedicine.medscape.com/article/1873373-overview Mark Obermann , Treatment options in trigeminal neuralgia, (2010) 3(2) 107-115