HIV. If your CD4 count is reasonable

HIV.

If your CD4 count is reasonable, an HIV patient is more likely to have stroke. He can have a meningitis. Now as the CD4 drops you go through TB and then AIDS-related dementia. Now when the count is very low you get PML, CMV lymphoma zoster. And crypto comes under here. So this is going to be of some practical use in differential diagnosis when you are dealing with these guys. There is no absolute rule here. CD4 is the lymphocytes that the AIDS virus affect, that destroy them. The clue for toxoplasmosis, very early focal signs. MRI lesions light up. Almost always basal ganglia is involved on MRI. Here is the treatment. Pyrithiamine sulfa. Clindamycin can be useful. Now you need to prevent toxo with half dose of these drugs. So once you treat them for four, six, eight weeks, keep the patient on maintenance dose because the toxo does recur. The maintenance dose is usually half the therapeutic dose.

Lymphoma: subacute onset. The lesions cross the midline then you find lesions close to the ventricles. The focal findings will be very similar to toxo sometimes but if MRI lesions cross the midline, think lymphoma. One you get toxo once, you are going to get it again. They need maintenance. Maintenance means maintenance for the rest of their life. You can look for Epstein-Barre PCR in the biopsy specimen, if the lesion is lymphoma. It’s not very sensitive but you may pick the virus particles in about 30 or 40% of lymphomas. If you are not sure between toxo and lymphoma, obviously you need to go for biopsy.

Crypto: clues, retinitis. If the scenario is a patient with AIDS, low CD4 count, has some visual blurring and has headache, think crypto. Polyradiculitis is common. It can catch the cranial nerves. PML: you saw PML JC virus. Symmetric demyelination on MRI. PML lesions do not enhance. That’s important. PML lesions do not enhance. Toxo enhances, lymphoma enhances. Lymphoma crosses the midline. Zoster, myelitis is common. CMV can produce myelitis. CMV can produce myeloradiculitis. CMV can produce polyneuropathy. There are a whole bunch of differential diagnoses. Any one of them can produce myelopathy. So if an AIDS person comes to you with transverse paraplegia on a sensory level it can be pretty tricky. A lot of times you may end up doing a bone marrow biopsy looking for toxo, look for PCR. The whole works. Sometimes you never find out.

HIV dementia complex. In children dementia is more common than infections, whereas in adults, infections are more common than dementia. Big, funny, giant cells. Atherogenesis is still a little bit uncertain. They don’t know how the virus actually affects the neurons. There are all kinds of theories here. Treatment for dementia: there is some evidence that treatment works for dementia. HIV myelopathy is the so-called vacuolar myelopathy slowly ascending. Numbness in the feet, legs stiff, legs weak. A month later the arms go numb and weak. So ascending myelopathy. Whereas infective myelopathy is more acute, definite transverse level. You can have myopathy very similar to polymyositis. AZT can produce myopathy. During seroconversion you can have a transient aseptic meningitis-like picture. Headache, throwing up for a week, then you get better. The virus can produce a chronic aseptic meningitis as well. So if you have a chronic meningitis on top of all the fungal stuff, you need to think of direct HIV meningitis also.

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