Objectives: To measure cerebrospinal fluid (CSF) tau in HIV infected patien
ts with acute neurological episodes and to correlate the findings with thr
type and severity of neurological disease.
Methods: CSF tau was prospectively measured in 76 consecutive HIV infected
patients admitted to a specialist unit at UCL Hospitals, London, for invest
igation of acute neurological episodes: the results were compared with the
Results: 24 patients had HIV associated dementia complex (HADC), 10 had lym
phoma (including four with primary CNS lymphoma), 20 had cerebral infection
s (including five with CMV encephalitis, five with VZV infection, seven wit
h cryptococcal meningitis, two with toxoplasmosis, and one with progressive
multifocal leucoencephalopathy); 22 patients had miscellaneous conditions,
including nine with self limiting headache/fever. 62 patients (82%) had no
rmal CSF tau concentration and 14 patients (18%) had elevated tau. In those
with HADC, there was no correlation between the degree of dementia or atro
phy on magnetic resonance imaging and CSF tau. Elevated CSF tau was associa
ted with poor outcome as six of eight patients who died within 4 weeks of l
umbar puncture had elevated tau (p=0.0024, two tailed Fisher's exact test).
Conclusions: CSF tau levels are not elevated in the majority of HIV infecte
d patients presenting with acute neurological episodes. CSF tau levels show
no correlation with severity of dementia/ atrophy on magnetic resonance im
aging. Although elevated CSF tau was observed in some patients with conditi
ons causing cerebral necrosis, the finding did not delineate underlying pat
hology but was associated with poor outcome.