Entrapment neuropathies

Entrapment Neuropathies are largely underdiagnosed.

1. ENTRAPMENT NEUROPATHIES PRESENTER:Dr. Bikash Ch.Nanda 1st YEAR,PG(INTERNAL MEDICINE) PRECEPTOR:Dr. L Ravi Kumar,MD Asst Professor Dept of Internal Medicine VSS MCH Burla

2. DEFINITION Entrapment Neuropathy is defined as: Pressure or Pressure induced injury to a segment of a peripheral nerve secondary to anatomical or pathological structures

3. INTRODUCTION entrapment neuropathies The nerve is injured by 1. chronic direct compression, 2. angulations 3. stretching forces causing mechanical damage to the nerve.

4. Anatomy

5. Anatomy

6. Anatomy

7. PATHOPHYISOLOGY Focal slowing of Nerve conduction is the principal electrophysiological feature of entrapment neuropathy Mild degrees of pressure(suprasystolic) applied to the nerve for short periods produce reversible dysfunction d/t ischemia(entrapped nerve more sensitive to ischemia than normal nerve) Acute ischemia may be responsible for paresthesias and dysethesias Prolonged ischemia may l/t neural tissue infarction

8. PATHOPHYSIOLOGY Peripheral nerve

9. PATHOPHYSIOLOGY Relevance *Epineurium protects against compression *Epineurium and perineurium protect against stretch NEUROPRAXIA:Segmental axonal conduction block CONDUCTION SLOWING:(in the absence of histological change) Myelin is slightly damaged,widening of nodal areas(NOT destruction of internodal segment)-longer time to activate Conduction is slowed,but not completely blocked Characteristic of Entrapment Neuropathies(Old term:Axonostenosis)

10. Double Crush and multiple crush syndromes A proximal level of nerve compression could cause more distal sites to be susceptible to compression. The summation of compression along the nerve would result in alterations of axoplasmic flow The possibility of a distal site of compression making the more proximal nerve susceptible to secondary compression : A reverse double crush . Systemic diseases such as obesity, diabetes, thyroid disease, alcoholism, rheumatoid arthritis and neuropatthies lower the threshold for the occurrence of a nerve compression and alter axoplasmic transport rendering that nerve more susceptible to develop compression neuropathy and act as a ‘crush’.

11. Double Crush Syndrome

12. Entrapment Neuropathy in Diabetes DM is a significant predisposing factor for entrapment neuropathies . TN-C( Tenascin -C) expression in the endoneurium is closely correlated with nerve function. Metabolic and phenotypic abnormalities of endoneurial and perineurial fibroblasts lies behind the vulnerability of DM patients to entrapment neuropathy. In contrast to angiopathies , retinopathy, and nephropathy, three representative complications of DM , mast cells do not play significant roles in the onset or progression of the entrapment neuropathy associated with DM. Ref : Histol Histopathol (2008) 23: 157-166 http://www.hh.um.es

13. Clinical scenario Either or all Pain Numbness Tingling Burning Weakness Muscle wasting(severe cases) in respective anatomical areas

14. Diagnosis Electro diagnosis: mainstay Nerve Conduction studies(NCS) Electromyography(EMG) NCS assess integrity of sensory and motor neurons EMG assess electrical activity of a muscle from a needle inserted into a muscle

15. ELECTROMYOGRAM

16. TYPES nerve Site of entrapment Median N.(wrist) (elbow) Ulnar N. (wrist) (elbow) Lower trunk or medial cord of branchial plexus Suprascapular N Post.interosseous N Common Peroneal nerve Lateral femoral cutaneous (meralgia paresthetica) Posterior tibial Interdigital plantar (Morton metatarsalgia) Obturator Carpal tunnel Btwn heads of pronator teres Guyon’s canal( ulnar tunnel) Bicipital groove,cubital tunnel Cervical rib or band at thoracic outlet Spinoglenoid notch Radial tunnel—at point of entrance into supinator Muscle (arcade of Frohse) Fibular tunnel Inguinal ligament Tarsal tunnel; medial malleolus–flexor Retinaculum Plantar fascia: heads of third and fourth metatarsals Obturator canal

17. Carpal Tunnel Syndrome

18. Why does Median Nerve get compressed? Median Nerve :Position and Morphology Round or oval at distal radius level Elliptical at the pisiform and hamate Morphology changes with flexion and extension Wrist flexion :elliptical shape flattens Wrist extension :least morphological change Frictional forces btwn the median N.adjacent tendons and the transverse carpal lig compounded by morphologic changes irritate nerve Mechanism: demyelination f/b axonal degeneration. Sensory and autonomic fibers affected before motor Epidemiology: F:M::3-10:1,Age peak 45-60yrs

19. Etiology Aging,female,Increased BMI,Square shaped wrist,short stature,dominant hand ,white race,caffeine,alcohol , nicotine Linked to body morphology,DM,thyroid disease,hereditary neuropathies,RA,Acromegaly,Amyloidosis High amounts of repititive wrist movements and exposure to vibration/cold Lack of aerobic exercise,preg,BF,Use of wheelchairs,walking aids,recent menopause,renal dialysis( elbow positioning during dialysis, upper extremity vascular-access, and underlying disease is one cause of ulnar entrapment.) REF: Journal of Research in Medical Sciences Oct 2012

20. Clinical PAIN :aching over ventral wrist extending distally to finger and proximally to forearm SENSORY :hyperasthesias,parasthesias Mus.atrophy and weakness are late findings Autonomic changes :Incr sensitivity to temp changes Intermittent sym and increase with driving,reading the paper,crocheting,painting

21. Sensory domain and muscular atrophy

22. Diagnosis ELECTRODIAGNOSIS 1st LINE INVESTIGATION Prognosticates severity and used to follow disease process over time Positive in >90 % pts. with clinical CTS Distal Motor latency is usually prolonged(50%) -stimulate the Med N> at the wrist, record at APB-latency >3.7-4.5ms is abnormal Distal sensory latency is abnormal -Antidromic sensory study: stimulate at wrist and record at index or middle finger,8cm distally->3.5ms Condn vel across carpal tunnel slowed:<41m/s

23. Diagnosis SPECIAL: Hoffman Tinel,Phalen,Reverse Phalen,carpal compression test,square wrist sign USG more cost effective and non invasive-may detect minute details which Electrophysiology may miss Lacks standardisation REF: J Korean Neurosurg Soc. Feb 2013; 53(2): 132–135

24. TREATMENT Physical therapy- Aerobic exercise,Modalities ( iontophoresis,phonophoresis,ultrasound ) Occupational therapy Work site ergonomic assessment (posture) Wrist-hand orthosis (worn at night for 3-4 wks) Stretching/strengthening Pharmacotherapy: NSAIDS,diuretics,steroids,Vit B6/12-no proven benefit,reduce caffeine,nicotine,alcohol intake Local 40mg methyl pred inj results in significant improvement in mild CTS Surgery-release of transverse carpal lig Indicated for failure of conservative care or severe category at presentation Open vs endoscopic REF:EURA MEDICOPHYS 2007;43:327-32 REF:Clin neurophysiol 2012 Apr;123(4):838- 41. doi: 10.1016/j.

25. Corticosteroids In CTS, steroid injections (such as cortisone or prednisolone ) shrink the swollen tissues and relieve pressure on the nerve. they offer short-term symptom relief in a majority of CTS patients. However, in about half of cases, symptoms return within 12 months. Generally a second injection does not provide any added benefit. Another concern with the use of these injections in moderate or severe disease is that nerve damage may occur even while symptoms are improving. Corticosteroid injections are helpful for pregnant patients, as their symptoms often go away within 6 - 12 months after pregnancy. Most doctors limit steroid injections to about three per year, because they can cause complications, such as weakened or ruptured tendons, nerve irritation, or more widespread side effects. Low-Dose Oral Corticosteroids. A short course (1 - 2 weeks) of oral corticosteroid medicines may provide relief for some people, but the relief does not usually last. Long-term use of these medications can cause serious side effects . Source : Carpal tunnel syndrome University of Maryland Medical Center

26. Recent Advances USG guided percutaneous injection,hydrodissection, and fenestration An extension of blind steroid injection with advantage of safety,accuarcy of medication placement,effectiveness,non invasiveness,ease of performance and lower cost than open surgical release REF: Vol.10,No.3,2010,Journal of Applied research

27. OTHER MEDIAN NERVE COMPRESSION SYNDROMES

28. Anterior Interosseous Nerve (AIN)syndrome Site of compression essentially same for both Pronator syndrome(PS) and AIN PS :Vague volar forearm pain,Median nerve parasthesias,minimum motor findings AIN :Pure motor palsy of any or all three 1.FPL,2.FDP of index and middle fingers,3.PQ. Surgical indications for nerve decompression include persistent symptoms for >6 months in patients with PS or for a minimum of 12 months with no signs of motor improvement in those with AIN syndrome

29. Cubital Tunnel Syndrome

30. CUBITAL TUNNEL SYNDROME MECHANISM Repititive bending or leaning on elbow for long periods Fluid build up in the elbow Trauma All of these cause narrowing and constriction of the nerve

31. Symptoms Aching pain on the inside of elbow Numbness, tingling ring and index finger esp when bending the elbow Weakening of grip,difficulty in finger coordination,muscle wasting- when more severe compression

32. Diagnosis

33. Treatment In situ or simple decompression Incising the aponeurotic arch between the olecranon and medial epicondyle if conservative treatment fails In situ decompression is simple and does not influence the blood supply of the ulnar nerve Second, it is also effective because it addresses the primary focus of the lesion, the cubital tunnel. Third, it has lower rate of postoperative complications and more opportunities for quicker rehabilitations Simple decompression, however, is not appropriate in a poor bed, severe cubitus valgus, or a subluxing nerve

34. Guyon’s canal entrapment Typically in cycling,wt lifters,jackhammers Seen also in hook of hamate compression of ulnar nerve at Guyon’s canal Symptoms may be motor or sensory Feeling of pins and needles in the ring and little fingers, which is often noticed in the early morning This may progress to a burning pain in the wrist and hand followed by decreased sensation in the ring and little fingers. The hand may become clumsy when the muscles controlled by the ulnar nerve become weak.

35. Treatment Proper bicycle fitting, handlebar adjustments, frequent change in hand position, handle bar and glove padding Wrist splints Surgical decompression from failed non-op mgmt., especially with structural lesions such as hook of hamate fracture

36. Radial Nerve Entrapment

37. Radial Nerve Entrapment Syndrome Radial nerve entrapment at one of 5 sites Anatomy - posterior cord to emerge between long and lateral heads of triceps, spiral groove of humerus proceeding medially to laterally to emerge between brachialis and brachioradialis on lateral elbow to enter the radial tunnel Susceptible: Racquet sports, rowing and wt. lifting

38. Radial Nerve Entrapment Sensory and motor complaints, although typically less weakness than with Posterior interosseous Nerve entrapment Dull, deep lateral elbow pain Tenderness over extensor muscle group Pain reproduced with resisted forearm supination with elbow flexed

39. Radial Nerve Entrapment May mimic or coexist with lateral epicondylitis Rx:Conservative neural mobilization techniques Neural mobilization is a manipulative technique by which neural tissues are moved, relative to their surroundings Surgery for persistent symptoms usually involves releasing the entrapped location

40. Posterior Interosseous Nerve (PIN)Syndrome PIN is a branch of the radial nerve, originating in the lateral intermuscular septum Purely motor function Innervates the supinator Most common in racquet sports, bowlers, rowers, discus throwers, golfers, swimmers All involve repetitive supination and pronation

41. PIN Syndrome Specifically, pain with resisted supination ; EMG/NCS may be helpful to differentiate between lateral epicondylitis and PIN Rx :minimize supination during rehabilitation

42. Suprascapular Nerve. Entrapment Throwers, other overhead athletes and weight-lifters Arises from superior trunk of brachial plexus Innervates supraspinatus and infraspinatus Compression most commonly suprascapular or spinoglenoid notch

43. Suprascapular Nerve Entrapment

44. Etiology Notch narrowing Ganglion cyst from intraarticular defect Often indicative of a labral (SLAP) tear Nerve kinking or traction from excessive infraspinatus motion Superior or inferior ( spinoglenoid ) transverse scapular ligament hypertrophy causing compression

45. Clinical Vague posterior shoulder pain, weakness and fatigability Weakness/atrophy without pain often suggests compression at spinoglenoid notch (nerve purely motor beyond this) Symptoms may mimic rotator cuff pathology or instability Exam reveals rotator cuff weakness and possibly supra- and/or infraspinatus atrophy

46. Infraspinatus atrophy Infraspinatus Atrophy

47. Diagnosis and Treatment MRI may exclude rotator cuff tears, demonstrate atrophy and/or reveal a ganglion or space-occupying lesion- if present, strongly consider surgical excision NCS/EMG may assist with the diagnosis Typically begin with non-operative mgmt. Rx :Rest from repetitive hyperabduction NSAIDs and corticosteroid injections considered Nonresponders may benefit from a spinoglenoid notchplasty, transverse scapular ligament release, nerve decompression or surgical exploration

48. Thoracic Outlet syndrome

49. Investigations Plain films may reveal a cervical rib or exuberant callus from a clavicle/upper rib fx MRI and MRA can reveal brachial plexus anatomy, subclavian vein anatomy or vascular occlusion/compression MRA with the arm in abduction can demonstrate subclavian vein obstruction in baseball pitchers

50. Treatment Nonoperative treatment focuses on rest, stretching of the nearby soft tissue structures and posture mechanics; gradual improvement Injection of botulinum toxin into the muscles of the thoracic outlet (scalenes, pectoralis minor, subclavius) has potential for obtaining long-term symptom relief, but further research is needed. REF : Foley JM, Finlayson H, Travlos A. A review of thoracic outlet syndrome and the possible role of botulinum toxin in the treatment of this syndrome. Toxins (Basel) . Nov 2012;4(11):1223-35. [Medline] Surgical treatments Rib resection Brachial plexus neurolysis and sympathectomy Effort thrombosis also treated with clot lysis with urokinase or heparin

51. Meralgia parasthetica

52. Meralgia parasthetica Mech: Compression (entrapment)may occur at the point where it passes between the two prongs of attachment of the inguinal ligament. Clinical :numbness,mild sensitivity of the skin,or occasionally persistent burning Perception of touch and pinprick are reduced in the territory of the nerve; there is no weakness of the quadriceps or diminution of the knee jerk. The symptoms are characteristically worsened in certain positions and after prolonged standing or walking

53. Diagnosis Dx : The sensory response is absent in 71% of patients with meralgia paresthetica and is prolonged in 24% Electromyographic test results with needle are normal which may help to differentiate it from an upper lumbar radiculopathy

54. Treatment Weight loss Adjustment of restrictive clothing or correction of habitual postures Neurectomy of the nerve, Hydrocortisone

55. Piriformis syndrome (false sciatica)because instead of actual nerve irritation, it is caused by referral pain. caused by tight knots of contraction in the piriformis muscle, Sciatica refers to irritation of the sciatic nerve, that arises from nerve roots in the lumbar spine. The most common cause of “true” sciatica is compression of one or more of its component nerve roots due to disc herniation or spinal degeneration in the lower lumbar region

56. Obturator Nerve entrapment

57. Etiology During delivery as a result of compression of the nerve between the head of the fetus and the bony structures of the pelvis, As a consequence of compression of the nerve between a tumor and the bony pelvis. in the obturator canal during surgery or with total hip arthroplasties . Malposition of the lower limb for prolonged periods, entrapment in the adductor magnus in athletes,

58. Diagnosis Clinical : difficulty with ambulation and the development of an unstable leg. Dx : Membrane instability (positive sharp waves and fibrillation potentials) will occur within 3 weeks of the nerve injury, and needle examination should be performed on patients with groin pain of longer than 3 months

59. Treatment With physical therapy, cryotherapy or a transcutaneous electrical nerve stimulation (TENS) unit may be tried. "TENS" is the acronym for T ranscutaneous E lectrical N erve S timulation. A "TENS unit" is a pocket size, portable, battery-operated device that sends electrical impulses to certain parts of the body to block pain signals. The electrical currents produced are mild, but they can prevent pain messages from being transmitted to the brain and may raise the level of endorphins (natural pain killers produced by the brain).

60. TENS

61. Common peroneal nerve entrapment habitual leg crossing, compression of the nerve against a bed railing or hard mattress in debilitated patients, or prolonged immobility, such as that observed in patients under anesthesia

62. Tarsal Tunnel Syndrome

63. Diagnosis Mech :Thickening of the tendon sheaths,or connective tissue or osteoarthritic changes Clinical : Tingling pain and burning over the sole of the foot develop after standing or walking for a long time Dx : EMG and NCV testing values include the following: Prolonged distal motor latency: Terminal latencies of the abductor digiti quinti muscle (lateral plantar nerve) longer than 7.0 ms are abnormal. Terminal latencies of the abductor hallucis muscle (medial plantar nerve) longer than 6.2 ms are abnormal. Fibrillations in the abductor hallucis muscle may be present.

64. Treatment Rest, NSAIDs, corticosteroid injection Footwear adjustments, including a medial arch support Surgical release ~75% success rate

65. Morton’s Metatarsalgia

66. Morton’s Metatarsalgia Mech :perineural fibrosis and nerve degeneration due to repetitive irritation Incidence :occurs most frequently in women (F:M 8:1) aged 40-50 who wear high-heeled, pointed-toe shoes Clinical :common digital nerve to the third/fourth metatarsal spaces is most often affected pain is only felt when the patient wears shoes. There is localized tenderness over the site of the neuroma Dx :USG is the modality of Choice Rx : If there is no relief from symptomatic padding then the neuroma may be excised

67. Research areas in nerve injury”Molecular factors ” CLASS AGENT(S) ACTION Neurotropic Factors and Chemoattractants Ciliary neurotrophic factor (CNTF) Nerve growth factor (NGF) Insulin-like growth factors (IGFs) Brain-derived neurotrophic factor (BDNF) NT-3 NT-4 Promote neuronal survival and regrowth Attract and guide axon Chemorepellent Factors Semaphorins Netrins Others Selectively repel some types of axons Inhibitors of Connective Tissue Formation Inhibitors of fibroblasts Collagenases Others Decrease fibrosis at the site of nerve injury to promote axonal regeneration

68. Summary

69. References Hassouna H, Singh D. Morton's metatarsalgia : pathogenesis, aetiology and current management. Acta Orthop Belg. 2005;71(6):646-55 Neurosurg Focus. 2009 Feb;26(2):E13. doi: 10.3171/FOC.2009.26.2.E13 Adam’s and Victor’s Principles of neurology Entrapment Neuropathies John D. England, MD

70. References Brain’s Textbook of Neurology Ann R Coll Surg Engl . Nov 2011;93(8):634-8. Sanders RJ, Hammond SL, Rao NM. Diagnosis of thoracic outlet syndrome. J Vasc Surg . Sep 2007;46(3):601-4

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