This document provides an overview of peripheral neuropathy including: - Classification based on anatomy (nerve location), pathology (demyelinating vs axonal), and etiology (hereditary, acquired). - Common hereditary neuropathies like Charcot-Marie-Tooth disease and Friedreich's ataxia. Acquired neuropathies discussed include Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, and diabetic neuropathy. - Evaluation involves clinical history, physical exam focusing on localization and symptom predominance, and may include labs, electrodiagnostic tests, and nerve biopsy. - Specific mononeuropathies, plexopathies, and myelopathies

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Peripheral Neuropathy
Ali Alrefai, MD

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Introduction
Classification
Approach to PN
Pathology
Mononeurpathies
Polyneuropathies:
Hereditary
Acquired
Plexus lesions
Myelopathies

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Classification
Anatomical:
Peripheral nerve lesion
Root & plexus
Cord lesion
Pathological:
Demyelinating
Axonal
Etiology
Hereditary
Acquired

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Clinical History
Time course:
GBS, diphtheria, porphyria
CIDP, hereditary, metabolic
Age of onset:
Medical history:
Drug & alcohol history: see Table 6-2
FH
Occupational history

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Motor Sensory Autonomic
Weakness Paresthesia Postural
hypotension
Cramps Dysesthesia B/B
dysfunction
Fasciculation Pain Impotence
Loss of
sensation
Impaired
sweating
Symptoms

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Localize the deficit:
Mononeuropathy
Mononeuropathy multiplex
Polyneuropathy
Motor; Sensory; Autonomic:
Predominantly motor
Predominantly Sensory
Autonomic involvement
Physical Examination

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CBC, ESR, FBS, TSH, B12, LFT, Hep screen,
SPEP, UPEP, Toxicology screen
Autoantibodies:
Anti-GM1
Anti-MAG
Paraneoplastic: Anti-Hu
NCS/EMG
CSF
Genetic
Nerve biopsy
Laboratory

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Pathology
(1) Axonal Loss:
Most common
DM, RF, Hereditary
Distal weakness
Absent reflexes
Distal sensory loss
NCS
Partial recovery

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(2) Myelin loss:
Hereditary
Immune-mediated neuropathies
compression
Weakness
Absent reflexes
Better prognosis
NCS
Onion bulb

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Wallerian Degeneration
Sequence of axonal & myelin loss
Distal segment of transected nerve
4-10 days after axonal loss
Proliferation of schwann cells; Phagocytes;
Fibroblasts

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Mononeuropathies

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(1) Median Neuropathy
Most common
CTS: Most common
Women 3:1, DM, rheumatoid arthritis,
hypothyroidism, pregnancy
Nocturnal numbness or pain
Dropping things: APB
+ Tinel’s, phalen’s signs
NCS/EMG
Splinting vs. surgical decompression

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(2) Ulnar Neuropathy
Elbow
Trauma, bone deformity, leprosy,
idiopathic
Elbow pain
Intrinsic hand muscle weakness
Paresthesia
NCS/EMG
Conservative vs. surgery

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(3) Radial Neuropathy
Humerus fracture
Pressure palsy
Crutches
Wrist drop, other extensors
Triceps & brachialis reflexes
Dorsal sensory loss
NCS/EMG

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(4) Common Peroneal Neuropathy
Compression:
Coma, prolonged bed rest, crossed legs
Trauma
Systemic disorders:
HNPP, DM, Leprosy
Foot drop, steppage gait
NCS/EMG
Rx:

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Polyneuropathies

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Hereditary Neuropathies
(1) Charcot-Maries-Tooth
Distal weakness
Wasting
Absent reflexes
Pes cavus
Demyelinating (CMT1); Axonal (CMT2)
AD, AR, X-linked

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(2) Friedreich’s Ataxia:
AR
Trinucleotide repeat (9q13-21)
Sensory loss
Absent reflexes
(3) HNPP:
AD
Simple or multiple mononeuropathies at
compression sites

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Acquired Neuropathies

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(1) Acute Idiopathic Inflammatory
Polyneuropathy (GBS or AIDP)
Clinical Features:
Acute to subacute
Preceding illness (Flue, GI, Vaccine..)
Distal ascending symmetric weakness
Respiratory involvement
Sensory complaints>finding
Absent reflexes
Autonomic
CN

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Cont GBS
Dx:
 CSF protein
Normal CSF cell count (<10)
NCS:
Slow motor velocity
HIV-1 in suspected patients
Rx:
Plasmapharesis, IVIG
Symptomatic: Respiratory, DVT,
Autonomic, Nutrition....
Prognosis:

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(2) Chronic inflammatory Demyelinating
Polyneuropathy (CIDP)
Chronic progressive or relapsing course
Similar to GBS
Similar CSF
Electrodiagnosis:
Demyelinating & axonal
Steroids
Plasma exchange, IVIG
Immunosuppression

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(3) Diabetic Neuropathies
0-93% may develop PN
Symmetric PN:
Mixed (most common)
Predominantly sensory
Autonomic
Asymmetric neuropathy:
Mononeuropathy multiplex
Lumbar radiculopathy (2nd common)
Cranial Neuropathy

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Cont. Diabetic Neuropathy
Rx:
Control blood glucose
Symptomatic:
Neuropathic pain
Dysautonomia

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(4) Vasculitic Neuropathy
Polyneuropathy; Mononeuropathy multiplex,
entrapment neuropathy
PAN, Rheumatoid arthritis, SLE, Wegener’s
granulomatosis
NCS/EMG
ESR, RF, ANCA.......
Steroids

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Plexopathies

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Brachial Plexopathy
C/F:
Weakness
Pain
Sensory loss
Reflex changes
Etiology:
Trauma
Compression: Tumors
Idiopathic: Parsonage Turner

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Myelopathies

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Clinical Features
Motor, sensory or bladder; combination
C5: Unilateral or quadriparesis
T1: LL paraparesis
Spasticity

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VITAMIN
Traumatic
Demyelinating
Infectious:
Epidural abscess
TB
AIDS
HTLV-1
Vascular:
Infarction
AVM

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