A 47 y.o. with newly discovered HIV presents with severe truncal ataxia and is unable to walk.

What do the arrows indicate on the MRI?

Our patient had progressive multifocal leukoencephalopathy which is a progressive viral infection  caused by the JC virus, a polyoma virus. The virus is found in up to 58% of the general population but causes disease  almost exclusively in patients with severe immune deficiency.  AIDS is the leading cause of PML but It can also occur in transplant patients,  Hodgkin’s lymphoma, multiple sclerosis, psoriasis and other autoimmune diseases.  The mortality rate is 30-50%.  Our patient had positive CSF for JC virus and the diagnosis was confirmed on T2 weighted MRI. 

Prior to the event of antiretroviral therapy 5% of people with AIDS eventually developed PML. It is similar to multiple sclerosis in that it is a demyelinating disease where the sheaths of axons are destroyed but progresses much more rapidly.

The standard cerebellar tests

THE DIAGNOSIS OF ATAXIA

Ataxia can result from any of three problems.

VISUAL PROBLEMS- Changes in vision can lead to problems with balance

PROPRIOCEPTION- awareness of where limbs are in space. This can result from lesions in the spinal cord as in tabes dorsalis or in lesions in the cerebellum as in the case of our patient.

THE VESTIBULAR SYSTEM- The labyrinth in the middle ear and can be affected by viral inflammation or trauma.

If any one of these systems is damaged, the others can compensate. For example in diabetic neuropathy where the patient loses the sense of where their feet are in space,  intense visual training can improve gait.  In Parkinson’s disease the labyrinthine element is lost before visual and proprioceptive. By compensating with latissimus dorsi in the back they can improve their proprioception and gait.

much more common than JC virus is cerebellar atrophy due to alcohol use

The danger of treating PML in AIDS is immune reconstitution inflammatory syndrome (IRIS) in which damage to the myelin actually increases with HAART.  Our patient was thought to have IRIS and treated with high dose steroids. He did not improve and was sent to a SNF.

 Interestingly, our patient had no nystagmus, no vertigo, no past pointing or heel to shin abnormalities. .  His ataxia was most  demonstrated only when he attempted to walk. Remember to walk your patients.

Egli ,A, Infanti L, Dumoulin A. enaunt al. prevalence of polyomavirus BK and JC infection and replication in 400 healthy blood donors.  Journal of Infectious Diseases. 199(6):837-46.

Ferenczy M, Marshal L, Nelson C, et al. Molecular biology, epidemiology and pathogenesis of progressive mutifocal leukoencephalopathy, the JC virus-induced demyelinating disease of the human brain.  Blin Microbiol. Rev. 25 (3):471-506.

Martin P.  the Basal Ganglia and Posture Lippincott Company, Philadelphia, 1967.

Sacks, O.  The Man who Mistook his Wife for a Hat. Touchstone. New York, 1966.