Peripheral Neuropathies

Peripheral neuropathies Dr. Osman Sadig Bukhari

Peripheral nerve diseases 1- Mononeuropathies 2- Multiple mononeuropathies (mononeuritis multiplex) 3- Polyneuropathies

Neuropathy = pathological processes damaging a nerve or nerves. The mechanisms of damage may be:- 1- Demyelination e.g. GB, diphth, HSMN 2- Axonal degeneration : e.g. Toxic neuropathies 3- Compression : Causes segmental demyelinatio e.g. Entrapment N. 4- Vasculopathy (infarction): Causes distal Wallerian degenerat e.g. DM, collagen diseases e.g. PAN. 5- Infiltration : e.g. leprosy, malig, sarcoidosis.

** With axonal degen nerve conduction velocity is normal or slightly reduced & EMG shows evidence of muscle denervation. ** With demyelination conduction velocity may be slowed considerably or blocked in severe cases without accompanying muscle denerv. **- Mononeuropathy e.g. compression - Multiple mononeuropathies e.g. vasculopath infiltr, radiation - Polyneuropathies e.g. hereditary, metab toxic, GB, non metastatic manif of malig

Poly neuropathies Causes 1- Inherited neuropathies : - Charcot - Marie- Tooth disease - Dejerine- Sottas disease - Refsum,s disease - Acute intermittent porphyria - Friedreich,s ataxia

2- Metab & endocrine: - DM - Uraemia - Chronic liver failure - Hypothyroidism - Acromegaly - Amyloidosis - Para & cryoproteinaemia

3- Toxic neuropathies : - Alcohol - Drugs ( INH, phenytoin, vincristine, ) - Heavy metals (lead, arsenic, Hg) - Organic solvents (acryl amide, organophos)

4- Infective: - Leprosy - Diphtheria - HIV - H. zoster

5- Inflammatory : - Guillian – Barre’ syndrome. - Chronic demyelinating polyneuropathy - Idiopathic chronic sensorimotor neuropathy - Connective tissue diseases - Sarcoidosis - Lyme borreliosis

6- Vitamin deficiency : - B12 - B1 - B6 - Folate - Nicotinic acid - Vit E

7- Neuropathy associated with malignant disease 8- Neuropathy associated wz critically ill pts

Modalities of polyneuropathies - Sensory - Motor - Mixed - Autonomic

C/F of Polyneuropathies 1- Sensory dysfn: numbness, paraesthesiae, hyperaesthesia & pain starting distally and ascending proximally in gloves & stockings with impaired perception of pain, touch, temp vibration & position sense. 2- Motor dysfn : flaccid weakness most marked distally. 3- tendon reflexes : depressed or absent.

4- Autonomic neuropathy : orthostatic hypot dysphagia, gastro paresis, gustatory sweating ( facial sweating wz anhydrosis of the feet), noct. diarrhoea, urine retention wz overflow incontinence, failure of erection, resting tachycardia, fixed HR, C/R arrest, dependant oedema wz cold feet, small non reactive pupils - Causes : - DM - GB - Acute intermittent porphyria - Amyloidosis - Drugs

Investigations : guided by sympt & signs The cause of polyneuropathy is suggested by the history including the onset, FH, PMH, DH, SH and za predominant clinical manifestations . - CBC & ESR - Renal profile & liver biochemistry - Blood glucose & thyroid fns. - ANF & RF - Plasma electrophoresis - Urinary levels of heavy metals. - CSF - CXR

- Serum lipids, lipo proteins, cry proteins - Vitamins assay - Urinary porphyrins - Genetics - Search for malig e.g. radiology, immaging, PSA, stools for occult blood, endoscopy, mamography - Nerve conduction studies - EMG - Nerve biopsy.

Inherited neuropathies 1- Charcot Marie Tooth syndrome - Mainly AD - presents in early adult life wz gait disturba or foot deformities. Slow nerve degeneratio lead to polyneuropathy wz distal weakness and wasting (inverted champagne bottle), variable sensory loss, absent kn & An jerks, high steppage gait due to foot drop - Pes cavus & claw feet +/- optic atrophy & deafness - Dis arrested in middle life. Normal life span.

2- Dejerine Sottas disease - AR or sporadic - Progressive motor & sensory polyn with weakness, ataxia, sensory loss & depressed or absent reflexes - palpable nerves wz segmental demyelination - High CSF proteins due to obstruction by nerve roots

3- Refsum’s disease - AD - Due to disturbance of phytanic acid metab. - Pigmentary retinal degeneration with progressive sensorimotor polyn & cerebellar signs. Auditory dysfn, cardiomyopathy and cutaneous manifestations - Marked reduction of conduction velocity - TR by restriction of phytanic acid and its precursors.

4- Acute intermittent porphyria - Mainly motor, proximal & UL > LL - Sensory manifestations may occur - Axonal in type -High CHO diet & conc. dextrose is helpful and propranolol for tachycardia & HT.

Neuropathies associated with metab and endocrine disorders 1- Diabetes mellitus (occur singly or in combin) - Symmetric sensory or mixed polyn - Asymmetric motor radiculopathy ( diabetic amyotrophy) - Mononeuritis or mononeuritis multiplex - Autonomic

2- Uraemia - Progressive sensorimotor polyn, LL > UL - Improves wz successful RT & to a lesser by chronic HD

Toxic neuropathies - Alcoholic polyn - Distal sensorimotor polyn frequently accomp by painful cramps, muscle tenderness and painful paraesthesia, often marked in za legs - Autonomic - May respond to B1 - Recurs or progress wz alcohol intake - Similar distal sensorimotor polyn occurs in beri beri (thiamine def)

Vitamin deficiency - Def states occur in malnutrition - preventable - potentially reversible if treated early 1- B12 def - Distal sensory polyn, sp proprioception - Absent ankle jerk - Extensor planter - Optic neuropathy - Intellectual dysfn

2- Thiamine def ( beri beri) - polyn - cardiac failure Werneckes Korsakoff psychosis (nystagmus, ophthalmoplegia, ataxia, amnesia, confusion coma - Parental B1 for TR 3- Pyridoxine def (B6) - Mainly sensory - More common in slow acetylaters on INH. - 10mg per day for TR

Infective neuropathies 1- Leprosy - In TL leads to hypo pigmented anaethetic patches & involves peripheral nerves of predeliction which are thickened - In LL leads to gloves & stockings sensory loss - Multiple mononeuropathy 2- Diphtheric neuropathy (demyelinating) - Palatal palsy I 1-2W - Loss of accomodation in2-4W - polyn in 4-6W

3- AIDS neuropathy - Chronic symmetric sensorimotor polyn - progressive polyradiculopathy or radiculomyelopathy ? CMV - Seropositive Pts may also develop demyeelinating polyradiculopathy and mononeuritis multiplex,

Inflammatory polyneuropathies 1- Acute post infective polyn - 1-4/52 following resp tract infection, campylobacter jejuni infection of za gut ( in 25% of cases, more severe & residual deficit), surgery & immunization - Demyelination of the spinal roots & periph N has probably immunological basis. - Patient presents wz distal weakness and numbness ascending over days to involve the face, resp muscles & bulbar muscles. - Patient may C/O back pain at za onset.

- Clinically there is muscle weakness, areflexia and variable sensory loss. Sphincters are intact & there is no sensory level. - Rapid deterioration wz resp failure may occur. - Ophthalmoplegia, ataxia & areflexia can be a presentation ( Miller Fissure) - CSF shows protein/ cell dissociation that may take 2-3 W to develop. - Nerve conduction velocity is slowed. - Investigations to search for a cause e.g CMV mycoplasma, campyl (CXR, stool culture and serology)

- DD include diphtheria, pophyria, lead N, ( pry motor N), botulism, polio & pry muscle disease - Treatment: - supportive ( ABC, nursing, physioth) - mechanical ventilation if resp paralysis occur. Monitor resp wz vital capacity. - Plasmapheresis & IV Ig if given early - Use of C/S is controversial. - complete recovery occur in 80% in 3-6 M - mortality 4% & 3% relapse. - remainder left wz disability.

Predominantly motor neuropathy 1- GB 2- Ca neuropath 3- Charcot Marie tooth disease (peroneal muscular atrophy 4- lead poisoning

Management of neuropathies 1- In 1/3 treatable cause: - toxins & offending drugs removed - Deficiencies & metab abn corrected - inflammatory causes by immunosuppression 2- In 1/3 there is identifiable cause but no TR as in hereditary 3- In 1/3 no specific cause -- Physiotherapy & occupational therapy

Mononeuropathies 1- Acute : sustained pressure e.g. tourniquet 2- Chronic: entrapment Causes according to site of compression 1- Carpal tunnel Median N 2- Cubital tunnel Ulnar N 3- Spiral groove of humerus Radial N 4- Inguinal ligament Lateral cutaneous of thigh 5- Neck of fibula Common peroneal N 6- Flexor retinaculum (tarsal tunnel) Post tibial

Mononeuritis multiplex Causes 1- leprosy (commonest) 2- DM 3- vasculitis 4- sarcoidosis 5- amyloidosis 6- malignancy 7- neurofibromatosis 8- HIV infection 9- Idiopathic multifocal motor neuropathy

Peripheral Neuropathies

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