Polyneuropathy: Causes, Symptoms, Diagnosis, and Treatment Overview

Polyneuropathy = symmetric, length-dependent dysfunction of multiple peripheral nerves.

Common Causes

• Diabetes (most common) – metabolic, vascular.
• Alcohol – toxic + nutritional (B1, B12, folate).
• Vitamin Deficiencies: B12, B1 (thiamine), B6 (excess or deficit), E.
• Autoimmune: GBS, CIDP, vasculitic, paraneoplastic.
• Toxins/Chemo: Platinum, taxanes, vincristine, heavy metals.
• Hereditary: CMT (Charcot-Marie-Tooth).
• Infectious: HIV, Lyme, leprosy, diphtheria.
• Systemic: Amyloidosis, hypothyroidism, uremia, critical illness.

Symptoms (Stocking-Glove Distribution)

• Numbness, tingling, burning pain (feet → hands).
• Weakness (distal first: foot drop, intrinsic hand wasting).
• Autonomic: orthostasis, gastroparesis, neurogenic bladder, erectile dysfunction.
• Balance impairment (loss of proprioception).

Diagnosis

• Nerve conduction studies (NCS) + EMG (demyelinating vs. axonal).
• Labs: glucose, HbA1c, B12, folate, TSH, SPEP, ANA, heavy metals.
• Skin biopsy (small fiber).
• Genetic testing (if hereditary suspected).

Treatment

1. Treat underlying cause (glucose control, B12 replacement, immunosuppression, toxin removal).
2. Symptomatic: gabapentinoids, SNRIs, TCAs, topical capsaicin/lidocaine.
3. Rehab: PT/OT for strength, balance, orthotics (AFO).
4. Foot care: daily inspection, proper shoes, podiatry.

Early diagnosis prevents irreversible axonal loss.