Polyneuropathy

1. Peripheral neuropathy
Damage to peripheral nerves

2. Types
Mononeuropathy- affects single nerve
Compression, trauma, ischemia, inflammation
Mononeuritis multiplex- multiple nerves
involved, asymmetrically
DM, vasculitides, SLE, sarcoidosis, leprosy, amyloid
Polyneuropathy- multiple nerves
involved, concurrently & symmetrically
DM, AIDP/CIDP, toxic/metabolic, hereditary

3. Polyneuropathy- classification
Axonopathy
Stocking & glove type sensory loss, diminished DTR
& autonomic function in involved areas
Toxins, DM, SACD, alcoholism, chemotherapy drugs
Myelinopathy
AIDP, CIDP
Neuronopathy
MND, Herpes zoster, Vincristine

4. Symptoms & signs
-ve symptoms/signs-
Sensory- numbness, tremor, gait abnormality
Motor- weakness, heaviness, gait abnormality
+ve symptoms/signs-
Sensory- tingling, pain, itching, pins & needles
Motor- cramps, tremor, fasciculations
Absent ankle jerk

5. Evaluation
History-
Pattern of onset- mostly LL>UL & distal>proximal
Progression- acute-AIDP or chronic-DM/hereditary
Fluctuation- toxin exposure
Other systemic diseases
Family history
Examination-
Palpate nerve- thickened-leprosy
Small-fibre- predominantly spinothalamic tract-
dysesthesias, impaired pain/temperature sensation,
autonomic dysfunction ±, Fabry’s dis./DM/amyloid
Large-fibre- predominantly posterior column-
areflexia, ataxia, severe motor dysfunction,
minor cutaneous sensory deficit

6. Diagnosis
Nerve conduction studies
Sural nerve (at ankle) biopsy,
specially for mononeuritis multiplex

7. Treatment
Correct underlying cause
Control of DM
Correction of vitamin deficiency
Rx of leprosy
Avoid alcohol
Immunosuppression for AIDP/CIDP
Surgery for carpal tunnel syndrome
Neuropathic pain-
Amitriptyline, Carbamazepine, Gabapentin,
Pregabalin

8. SACD
Sub-acute combined degeneration
Due to vitamin B12 deficiency
Manifestation-
Paresthesias, sensory loss- LE>UE
Ataxia
Loss of ankle jerk, extensor plantar
Memory loss
Reduced vision, central scotoma
Sphincter disturbance
Rx- vitamin B12 supplementation, IM