CMV Polyradiculopathy

Cytomegalovirus polyradiculopathy is an opportunistic infection of lumbosacral nerve roots in advanced HIV (CD4 count under 50 cells/microlitre) and other severe immunosuppression, which presents as rapidly progressive cauda equina syndrome. It has become rare since antiretroviral therapy.

Pathophysiology. Reactivated cytomegalovirus causes a necrotising inflammatory polyradiculitis of the cauda equina, with a neutrophilic CSF response. Concurrent CMV retinitis, colitis or pneumonitis may be present.

Subacute (days to weeks) ascending flaccid paraparesis with severe radicular pain, areflexia, saddle sensory loss, urinary retention and faecal incontinence. Sensation may be relatively spared early.

Red flags.

• Progressive leg weakness with urinary retention in a patient with a CD4 count under 50 cells/microlitre.
• Visual symptoms (retinitis).

CSF shows neutrophilic pleocytosis (hundreds of cells), raised protein and low glucose, and CMV PCR positive in more than 90%. MRI of the lumbosacral spine shows clumped, thickened and enhancing nerve roots. Check plasma CMV load, CD4 count and HIV viral load. Dilated fundus examination looks for retinitis. Exclude varicella zoster virus, syphilis, lymphoma and tuberculosis.

Differential diagnosis.

• Lymphomatous meningitis, tuberculous radiculitis and neurosyphilis.
• Herpes simplex and varicella zoster radiculitis, Guillain-Barre syndrome and CIDP.
• Compressive cauda equina syndrome.

Start immediately, as neurological loss is hard to reverse.

Induction (2 to 3 weeks, until improving). Ganciclovir 5 mg/kg IV every 12 hours, adjusted to renal function, with or without foscarnet 60 mg/kg IV every 8 hours (or 90 mg/kg every 12 hours) for severe disease or resistance, with hydration and monitoring of renal function and electrolytes.

Maintenance. Valganciclovir 900 mg orally daily until CD4 count is above 100 cells/microlitre for at least 3 to 6 months.

Antiretroviral therapy. Start within 2 weeks of anti-CMV therapy. Watch for immune reconstitution.

Monitoring. Full blood count (neutropenia on ganciclovir, with stopping if neutrophils fall below 0.5 x 10^9/L), renal function, CSF PCR, and fundus.

Rehabilitation. Catheterisation, physiotherapy and venous thromboembolism prophylaxis.

Referral and escalation. Refer urgently to infectious diseases.

Special groups. Ganciclovir and foscarnet need dose adjustment in renal impairment. In pregnancy, treat with specialist advice given foetal risk.