Paraesthesia and numbness

Probability diagnosis

Diabetic peripheral neuropathy

Nutritional peripheral neuropathy esp. alcohol, B₁₂, folate

Hyperventilation with anxiety

Nerve root pressure e.g. sciatica, cervical spondylosis

Nerve entrapment esp. carpal tunnel syndrome

Neurotoxic drugs

Serious disorders not to be missed

Vascular:

• CVA/TIA

• Peripheral vascular disease

Infection:

• AIDs

• Lyme disease

• Leprosy

• Some viral infections

Tumour/cancer:

• Disseminated malignancy

• Cerebral/spinal cord tumours

Other:

• CKF: uraemia

• Guillain–Barré syndrome

• Trauma to spinal cord

• Marine fish toxins e.g. toadfish, Ciguatera

Pitfalls (often missed)

Migraine variant with focal signs

Multiple sclerosis/transverse myelitis

Hypocalcaemia

Rarities:

• Chronic inflammatory polyneuropathy

• Charcot–Marie–Tooth syndrome

• Amyloidosis

• Heavy metal toxicity e.g. lead

Masquerades checklist

Diabetes

Drugs e.g. cytotoxic agents, interferon (see list)

Anaemia: pernicious anaemia

Thyroid/other endocrine: hypothyroid?

Spinal dysfunction

Is the patient trying to tell me something?

Consider conversion reaction (hysteria), severe anxiety disorder. Some cases may be idiopathic.

Key history

Analyse symptoms: the nature, distribution, onset and associated neurological symptoms (motor, sensory), such as vertigo, seizures, vision. Check for other associated general symptoms such as fever, weight loss, pruritus, rash, weakness.

History of diabetes, migraine, cancer, spinal problems, injury, possible bites, fever/sweating and other symptoms. Take a travel and diet history, incl. nutrition and alcohol. Gather a drug history, particularly cancer therapy, interferon, colchicine, thalidomide, statins, alcohol or any illicit drugs.

Check the patient’s occupational history, e.g. exposure to lead, and psychiatric history, esp. anxiety states.

Key examination

• General health and nutritional status.

• Focused neurological especially sensory, motor function, reflexes.

• Look for ‘glove and stocking’ distribution, muscle wasting e.g. thenar eminence.

• Peripheral vasculature.

Key investigations

First line:

• urinalysis

• blood sugar

• FBE

• ESR/CRP

Consider:

• serum calcium

• B₁₂ and folate

• LFTs (γGT)

• U & E

• TFTs

• KFTs

• nerve conduction studies

According to clinical findings (refer):

• imaging e.g. spine, carotid vessels, CT or MRI, angiography

• specific blood tests for infection

• lumbar puncture (CSF protein, oligoclonol I_g G, etc)

Diagnostic tips

Take a detailed drug history including the above, alcohol and OTC medications. Intermittent perioral paraesthesia indicates hypocalcaemia associated with hyperventilation. In many cases of peripheral neuropathy or a sensory symptoms, the diagnosis is not only elusive but may not be identified.