SIXTH CRANIAL NERVE PALSY- Diagnosis and management

A COMPLETE PPT ON SIXTH CRANIAL NERVE PALSY ALONG WITH IT'S DIAGNOSIS AND MANAGEMENT

1. Cranial Nerve 6 Palsy DR. Arvind kumar morya Mbbs , ms ophthalmology, mnams , Cataract (mics), glaucoma, paediatric ophthalmology, Strabismus, refractive and medical retina services, Associate professor and head, Department of ophthalmology, Aiims , jodhpur

2. ANATOMICAL CONSIDERATIONS THE ABDUCENT NERVE ORIGIN, COURSE AND ACTIONS

3. FUNCTIONAL COMPONENTS

4. NUCLEUS LOCATION Lower part of Pons In the floor of fourth ventricle Either side of mid-line Deep to the facial colliculus

5. NUCLEUS ABDUCENT NUCLEUS - Small spherical mass of multipolar neurons - Wound round by fibres of CN VII - Lies dorsolateral to Medial longitudinal bundle (MLB) PARAABDUCENT NUCLEUS - Collection of small multipolar neurons - Lies dorsolateral to abducent nucleus - Connects it to opposite CN III nucleus through MLB ACCESSORY ABDUCENT NUCLEUS - Lies ventrolateral to abducent nucleus - Innervates nictitating membrane

6. COURSE

7. RELATIONS AT ORIGIN - 2 abducent nerves are 1 cm apart at the site of origin. - 2 vertebral arteries join to form basilar artery in between 2 nerves. - Lateral to its emergence is emergence of facial nerve - Inferior to it lies hypoglossal nerve

8. SUPRANUCLEAR CONTROL

9. MOTOR CORTEX OF CEREBRUM Connected to the pre-central gyrus of opposite side via CORTICONUCLEAR FIBRES. The area for eye is represented between thumb and nose. Stimulation leads to cortical type of movements. PRE-CENTRAL GYRUS

10. FRONTAL LOBE OF CEREBRUM - OCULOGYRIC AREA : Controls the voluntary movements of the eye - Lies in the posterior part of MIDDLE FRONTAL GYRUS OCULOGYRIC AREA

11. Control from frontal lobe of cerebrum - Fibres from oculogyric area descend as aberrant pyramidal tract, in the genu of internal capsule. -Some fibres cross, reach the vertical gaze centre of both the sides and end in CN III B/L - Other fibres descend to pons para abducent nucleus (horizontal gaze centre). Cross and end in horizontal gaze centre. - Centre is connect to CN VI which is connected to CN III via MLB

12. Effect of stimulating various parts of oculogyric area STIMULUS AREA EFFECT BILATERAL STIMULATION OF UPPER PART ROTATES THE EYE BALL DOWNWARDS

13. Effect of stimulating various parts of oculogyric area STIMULUS AREA EFFECT BILATERAL STIMULATION OF LOWER PART ROTATES THE EYE BALL UPWARDS

14. Effect of stimulating various parts of oculogyric area STIMULUS AREA EFFECT UNILATERAL STIMULATION OF UPPER PART ROTATES THE EYE BALL DOWNWARDS ON THE OPPOSITE SIDE WITH CLOSURE OF EYELIDS

15. Effect of stimulating various parts of oculogyric area STIMULUS AREA EFFECT UNILATERAL STIMULATION OF LOWER PART ROTATES THE EYE BALL UPWARDS ON THE OPPOSITE SIDE WITH OPENING OF EYELIDS

16. Effect of stimulating various parts of oculogyric area STIMULUS AREA EFFECT UNILATERAL STIMULATION OF MIDDLE PART ROTATES THE EYE BALL HORIZONTALLY ON THE OPPOSITE SIDE

17. OCCIPITAL CORTEX CONNECTIONS - AREA NO. 18: PERISTRAITE CORTEX - AREA NO. 19: PARASTRIATE CORTEX OCCIPITAL CENTRE OCCIPITAL CENTRE SPLENIUM OCULOGYRIC AREA OCULOGYRIC AREA SUPERIOR LONGITUDINAL BUNDLE SUPERIOR LONGITUDINAL BUNDLE SUPERIOR COLLICULUS HORIZONTAL GAZE CENTRE

18. EFFECT OF STIMULATION OF VARIOUS PARTS UPWARD CONJUGATE MOVEMENT DOWNWARD CONJUGATE MOVEMENT

19. BASAL GANGLIA

20. TRIGEMINAL NUCLEUS & CEREBELLUM - Connected to MESENCEPHALIC NUCLEUS of trigeminal nerve - Mesencephalic nucleus receives proprioceptive impulses from the muscles - Mesencephalic nucleus Superior cerebellar peduncle Cerebellum (Dentate nucleus) Oculomotor nuclei of both sides

21. MEDIAL LONGITUDINAL BUNDLE - Connects the three oculomotor nuclei - Helps in conjugate movement of eye - Also connects them to : 1. Facial 2. Stato -acoustic 3. Nucleus ambiguous 4. Hypoglossal 5. Cervical segments of the spinal cord.

22. ETIOLOGY LOCALIZING AND NON-LOCALIZING CAUSES

23. LOCALIZING CAUSES Pontine Syndromes : Tumour, Infarction, Demyelination Cerebellopontine Angle Lesions : Acoustic neuroma, Meningioma Clivus Lesions : Nasopharyngeal carcinoma, Clivus chordoma Middle Fossa Disorders : Tumour, Inflammation of medial aspect of petrous Cavernous Sinus Or Superior Orbital Fissure : Tumour, Inflammation, aneurysm Carotid-cavernous Or Dural Arteriovenous Fistula

24. NON-LOCALIZING CAUSES Increased Intracranial Pressure Intracranial Hypotension Head Trauma Lumbar Puncture Or Spinal Anaesthesia Vascular Hypertension Diabetes Para-infectious Processes Basal Meningitis

25. COMMON ETIOLOGIES Collier’s sphenoidal palsy Superior orbital fissure syndrome Arteriosclerosis Hypertension Diabetes Trauma and Raised ICT

26. ETIOPATHOLOGIES ACCORDING TO THE AGE GROUP PAEDIATRIC AND ADULT

27. Paediatric Congenital - Rare - Due to birth trauma, hydrocephalus, cerebral palsy Acquired. - neoplasm - trauma - inflammation - idiopathic - benign recurrent sixth nerve palsy

28. Paediatric - elevated intracranial pressure - pontine gliomas - following ear or throat infections or viral illness. Pontine glioma. Brainstem gliomas are particularly common in the pediatric population, and more than 80% arise from the pons with the peak age of onset between 5-8 years of age.

29. Paediatric Trauma, secondary to open or closed head injuries

30. Paediatric Elevated intracranial pressure due to shunt failure, pseudotumor cerebri , posterior fossa tumors , neurosurgical trauma, venous sinus thrombosis, meningitis, or Lyme disease

31. Paediatric Intracranial tumor Posterior fossa tumors : such as pontine glioma, medulloblastoma , ependymoma , cystic cerebellar astrocytoma can produce unilateral or bilateral abducens nerve palsies in children. Abducens nerve palsy can also present as a postoperative complication after resection of posterior fossa tumors in the pediatric population

32. Meningitis Hanna and others found abducens nerve palsy in 16.5% of patients with acute bacterial meningitis. Cranial nerve palsies in this setting tend to be multiple and bilateral.

33. Adult Microvascular ischemia. Trauma. Idiopathic. Less likely: Multiple sclerosis. Neoplasm. Stroke. Sarcoidosis/vasculitis. Increased intracranial pressure. Giant cell arteritis. Skull base tumors (meningioma, chordoma , nasopharyngeal carcinoma, metastasis) predominate in the adult population.

34. SYNDROMES OF CRANIAL NERVE VI THE SIX SYNDROMES OF CRANIAL NERVE 6

35. I. Brainstem syndromes (pathogenesis) - VI Nerve nucleus contains motor neurons that supply the lateral rectus muscle and internuclear neurons that project via medial longitudinal fasiculus to medial rectus subdivision of contralateral oculomotor nucleus. - Adjacent structures that may be affected : 1. Oculosympathetic central neuron: I/L Horner’s syndrome. 2. PPRF: I/L Conjugate gaze palsy 3. MLF: I/L INO 4. Pyramidal tract: C/L Hemiparesis

36. The brainstem syndromes: 1. Millard Gubler syndrome: CN VI paresis I/L CN VII paresis C/L Hemiparesis 2. Raymond syndrome: VI Nerve paresis C/L Hemiparesis 3. Foville’s syndrome: Horizontal conjugate gaze palsy I/L V, VII, VIII paresis I/L Horner’s syndrome

37. II. Subarachnoid space syndrome (pathogenesis)

38. III. The Petrous apex syndromes 1. Gradenigo syndrome: - Due to localized inflammation or extradural abscess of petrous apex following complicated otitis media - Clinical findings: A. VI Nerve palsy B. I/L Decreased hearing C. I/L Facial pain along distribution of CN V D. I/L Facial palsy

39. The Petrous Apex Syndromes: 2. Petrous bone fracture: - Base skull # following head trauma - Potential cranial nerve involvement: V, VI, VII, VIII - Haemotympanum - Mastoid ecchymosis - CSF Otorrhoea - Battle’s sign 3. Pseudo- Gradenigo’s syndrome: - Nasopharyngeal carcinoma: serous otitis media Obstruction of the Eustachian tube and invasion of cavernous sinus Causing VI nerve paresis

40. The Petrous Apex Syndromes: - Cerebellopontine angle tumour: may cause VI nerve paresis and other clinical findings, including: A. Decreased hearing B. VII nerve palsy C. V nerve paralysis D. Ataxia E. Papilloedema

41. IV. The Cavernous sinus syndrome - Association of CN III, IV, VI - Carotid occulosympathetic plexus - Optic nerve and chiasm - Pituitary gland

42. V. The Orbital Syndrome - Proptosis is an early sign - Conjunctival congestion and chemosis - Optic nerve may appear normal, oedematous or atrophied. - Trigeminal signs limited to ophthalmic division

43. VI. Isolated VI Nerve Palsy - Seen as post-viral neuropathy in young and ischemic mononeuropathy in adults. - Rule: Ocular motor cranial nerve palsy in young : greater likelihood of neoplasm and in older patient greater likelihood of ischemic mononeuropathy .

44. CLINICAL FEATURES THE HORIZONTAL DIPLOPIA

45. SYMPTOMS Horizontal diplopia: Uniocular Painless Increase on looking towards lateral side. More for distance than near

46. Signs Limitation of abduction Esotropia in primary position Uncrossed horizontal diplopia : increased towards paralysed side, horizontal displacement of image, vertical displacement in adduction , field of binocular vision constricted on affected side. Slight face turn towards the side of diplopia Early incomitant deviations ( Secondary > Primary) Late comitant deviations Then incomitant deviations (Primary > Secondary)

47. WORK UP OF A CASE OF CN VI PALSY

48. HISTORY - Chief complaint: Inward deviation of eyes Diplopia in acquired cases Face turn on same side Associated complaints of headache or hearing loss - History of presenting illness: Age of onset Mode of onset: Acute or chronic Diplopia: Type/Worse in gaze/ less or absent for near Head posture: Face turn on I/L side

49. HISTORY - Past history: Febrile disease: Viral illness Diabetes Mellitus Raised ICT Trauma Cerebral Palsy - Past surgical history : Neurosurgical procedure

50. Examination SYSTEMIC: OCULAR: 1. Visual acuity 2. Abnormal head posture 3. Ocular motility 4. Eyelid 5. Conjunctiva 6. Cornea/Sclera/Iris 7. Pupil 8. IOP/Lens/Vitreous/Fundus

51. Examination 9. Special test: Cover test Past pointing Diplopia charting Binocular function : Worth 4 Dot test , Bagolini’s striated glass, Maddox rod, Synaptophore Hess Charting Force duction test Active force generation test

52. SYSTEMIC EXAMINATION - Blood Pressure - Cranial nerve examination : V, VII, VIII CN V: Sensory – Pin prick to test facial sensation, Corneal reflex test Motor - Palpating masseter when patient clenches teeth, asking patient to open mouth against resistance CN VII: Assymetry of facial movements, Taste in Anterior 2/3 rd of tongue CN VIII: weber’s test, Rinne’s test

53. OCULAR EXAMINATION : 1. Visual acuity: Hampered if the deviated eye fails to fixate leading to amblyopia Assessed using Snellen’s chart, Jaeger’s chart 2. Abnormal Head posture: Face is turned to the affected side. 3. Ocular motility: Esotropia in primary position( due to relatively unopposed action of medial rectus, characteristically worse for distance. 4. Eyelid: Usually normal

54. OCULAR EXAMINATION : 5. Conjunctiva: Conjunctival injection or chemosis 6. Cornea/Sclera/Iris: Usually normal. Corneal sensations may be reduced in acoustic neuroma 7. Pupil: Usually normal 8. IOP/Lens/Vitreous/Fundus: Papilloedema

55. Cover test - Carried out with or without abnormal head posture - Should be done in all 9 gazes ( at least in dextro or levo version) - Amount of deviation will be more in the direction of involved muscle. - Should also be done with either eye fixing

56. Worth 4 dot test

57. Maddox rod test

58. Bagolini striated glass test

59. Diplopia Charting Right Sided CN VI Palsy

60. Hess Chart RE CN VI palsy -

61. Forced duction test - To look in mechanical restriction due to medial rectus. - After topical anaesthesia, the examiner passively moves in the direction opposite to the direction in which mechanical restriction is suspected.

62. ACTIVE FORCE GENERATION TEST After topical anaesthesia, the paralytic muscle is held with forceps. Patient is asked to move in the direction of limited duction . The amount of force generated by the muscle is felt as a tug by the examiner.

63. INVESTIGATIONS

64. Laboratory test Complete blood cell (CBC) count Glucose levels Glycosylated hemoglobin (HbA1C) Erythrocyte sedimentation rate and/or C-reactive protein Fluorescent treponemal antibody-absorption test, VDRL or RPR Lyme titer Glucose tolerance test Antinuclear antibody test

65. Rheumatoid Factor test MRI is indicated for the following: Patients younger than 45 years Associated pain or other neurologic abnormality History of cancer Bilateral sixth nerve palsy Papilledema Patients younger than 55 years with no vasculopathic history In the event no marked improvement is seen or other nerves become involved An LP can be considered if MRI results are negative.

66. MANAGEMENT

67. General treatment Treatment depends on etiology of the abducens nerve palsy. In general, underlying or systemic conditions are treated primarily. Most patients with a microvascular abducens nerve palsy are simply observed and usually recover within 3-6 months.

68. Treatment for diplopia Prisms: Base-out Fresnel prisms can be used to help the patient maintain binocular single vision in the primary position, but are not usually useful due to the incomitance of the deviation.

69. Management of diplopia Occlusion: Occlusion using Bangerter filter or pirate patch can eliminate diplopia and confusion, prevent amblyopia or suppression in younger patients, and decrease the possibility of ipsilateral medial rectus contracture.

70. Management of diplopia Botulinum Toxin: Botulinum toxin injections to the medial rectus of the affected eye is sometimes used to prevent secondary contraction of the medial rectus, or during transposition procedures to weaken the muscle not operated on. Surgery: In general, surgical intervention is reserved for patients who have had stable orthoptic measurements for at least 3-6 months. 

71. Surgery Strabismus surgery can be performed for persistent abducens nerve palsies that demonstrate stable measurements over 6 months period. Forced duction test is performed in the office or in operating room in order to assist with surgical planning. Types of surgery: A. A resection of the affected lateral rectus and recession of the ipsilateral medial rectus (recess/resect or “R and R” procedure) is performed. B. Resection of the affected lateral rectus with a recession of the contralateral medial rectus may be performed. C. Various forms of transposition surgeries can be considered. Jensen, Hummelsheim , Augmented Hummelsheim with resections +/- Foster modifications, Knapp's procedure are some of the examples. Botulism toxin can also be used as a temporizing treatment.

72. Types of surgeries A. A resection of the affected lateral rectus and recession of the ipsilateral medial rectus (recess/resect or “R and R” procedure) is performed. B. Resection of the affected lateral rectus with a recession of the contralateral medial rectus may be performed.

73. Types of surgery Jensen’s procedure Transposition of half thickness SR and Half thickness IR to LR

74. Types of surgeries HUMMELSCHEIM PROCEDURE Total transposition of SR and IR to LR

75. Types of surgeries AUGMENTED HUMMELSCHEIM: BROOK’S AUGMENTATION Resection of 4-6 mm of transposed recti. FOSTER’S MODIFICATION : Transposed recti are tied together 4-6 mm posterior to insertion.

76. Types of surgeries KNAPP’S PROCEDURE MR and LR are transposed superiorly to SR

77. Surgical follow up Patients must be managed closely postoperatively, and any residual diplopia can be managed with prisms. Complications The most likely complication following surgical correction of abducens nerve palsy is the risk of over- or under-correction, which can be managed postoperatively with prisms. Prognosis The prognosis for sixth nerve palsy depends on the underlying etiology.   Rush and Younge reported a recovery rate of 49.6% in 419 nonselected sixth nerve palsy cases, and a higher rate of 71% in 419 patients with diabetes mellitus, hypertension, or atherosclerosis.

78. ACKNOWLEDGEMENT: Dr. Anushree Naidu, Post-graduate student, Department of Ophthalmology, AIIMS, Jodhpur

79. THANK YOU