When is CT + LP indicated in the patient with HIV / AIDS
Quick tip for estimating CD4 count in ED
CD4 < 200 significantly raises risk for opportunistic infections.
- Absolute lymphocyte count < 1000 correlates to CD4 count < 200.
- Predictive value 91% [1]
- Absolute lymphocyte count > 2000 correlates to CD4 count > 200.
- Predictive value 95% [1]
Patient with CD4 <200 or ALC <1000
- Even vague complaints including fever, headache, and/or malaise may have CNS infections. [2]
- Obtain CT followed by LP.
- CSF WBC counts and glucose may appear normal despite a concomitant CNS infection [3]
- Initiate empiric treatment until cutlures and antigen testing returns.
- Consider CT with and without contrast
- Contrast shows ring-ehanching lesions of toxoplasmosis.
Patient with CD4 >200 or ALC >2000
- Clinical decision rule developed in cohort of 110 HIV positive patients.
- 100% sensitivity in ruling out new intracranial lesions [4]
- New or different headache than usual?
- Headache lasting more than three days?
- Focal neurologic deficit?
- Altered mental status?
- New-onset seizure?
- If none of these are present, it is considered safe to forego CT and LP.
- 100% sensitivity in ruling out new intracranial lesions [4]
Special considerations in differential for HIV pt w/ CNS symptoms
- Includes fever, malaise, headache, focal weakness, etc.
- Cryptococcal meningitis
- Toxoplasma gondii
- Progressive multifocal leukoencephalopathy
- CNS lymphoma
- Guillain-Barré
- Shapiro, Nathan I., et al. “Absolute lymphocyte count as a predictor of CD4 count.” Annals of emergency medicine 32.3 (1998): 323–328. ↩
- Graham III, Cole Blease, et al. “Screening CT of the brain determined by CD4 count in HIV-positive patients presenting with headache.” American journal of neuroradiology 21.3 (2000): 451–454. ↩
- Clark, Rebecca A., et al. “Spectrum of Cryptococcus neoformans Infection in 68 Patients Infected with Human Immunodificiency Virus.” Review of Infectious Diseases 12.5 (1990): 768–777. ↩
- Rothman, Richard E., et al. “A Decision Guideline for Emergency Department Utilization of Noncontrast Head Computed Tomography in HIV‐infected Patients.” Academic emergency medicine 6.10 (1999): 1010–1019. ↩
Tags: Core Content, infectious disease, neurology