Peripheral nerve disorders in HIV infection

DSPN is the commonest neurological complication encountered in HIV patients, with 30% of AIDS individuals experiencing symptoms. It is unusual in the asymptomatic stages of HIV infection.

The neuropathy due to the nucleoside analogue drugs (ddl, ddC and D4T) is similar and therefore difficult to differentiate from DSPN. These drug related neuropathies are dose dependent and reversible. However, patients may continue to deteriorate for 6—8 weeks after stopping the drug — “coasting”.

Box 8.10 Symptoms and signs of DSPN

• Numb, burning feet

• Pins and needles

• Contact hypersensitivity

• Little or no weakness

• Impaired pain and temperature sensation

• Depressed or absent ankle jerks

Box 8.8 Symptoms and signs of HIV dementia

Early

• Poor concentration

• Forgetfulness

• Clumsiness

• Unsteady gait

• Apathy

• Impaired eye movements

• Brisk reflexes

• Slowed fine finger movements

Late

• Global dementia

• Incontinent of urine and faeces

• Seizures

• Spastic paraparesis (due to vacuolar myelopathy)

• Myoclonus

Figure 8.6 T2-weighted MRI scan showing “milky” hyperintensity of the hemispheric white matter due to HIV dementia

Box 8.9 Peripheral nerve disorders in HIV infection

HIV related

• Axonal neuropathy (distal sensory peripheral neuropathy, DSPN)

• Demyelinating neuropathy — acute (Guillain-Barre syndrome), chronic (CIDP)

• Vasculitic neuropathy (mononeuritis multiplex)

• Diffuse infiltrative lymphocytic syndrome (DILS)

CMV related

• Vasculitis (mononeuritis multiplex)

• Lumbosacral polyradiculopathy

Toxic

• ddl, ddC, D4T

• isoniazid

• thalidomide

• dapsone

Box 8.11 Investigations in HIV neuropathy

• Neurotoxic drugs, including excess vitamin B₆

• Excess alcohol

• Blood tests: vitamin B12, glucose, VDRL, vitamin E (if severe diahorrea)

• Nerve conduction tests — only if marked weakness or unusual presentation

• Nerve biopsy may be indicated to exclude an inflammatory neuropathy (vasculitis or demyelination)

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