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HIV-1 Associated Opportunistic Infections - CNS Toxoplasmosis: Differential Diagnoses & Workup

Author: Niranjan N Singh, MD, DNB, Assistant Professor of Neurology, University of Missouri Columbia
Coauthor(s): Florian P Thomas, MD, MA, PhD, Drmed, Director, Spinal Cord Injury Unit, St Louis Veterans Affairs Medical Center; Director, National MS Society Multiple Sclerosis Center; Professor, Department of Neurology and Psychiatry, Associate Professor, Institute for Molecular Virology, and Department of Molecular Microbiology and Immunology, St Louis University
Contributor Information and Disclosures

Updated: Feb 23, 2007

Differential Diagnoses

Cardioembolic Stroke
HIV-1 Associated Opportunistic Infections: Cytomegalovirus Encephalitis
HIV-1 Associated Opportunistic Infections: PML
HIV-1 Associated Opportunistic Neoplasms: CNS Lymphoma
HIV-1 Associated Vacuolar Myelopathy

Other Problems to Be Considered

Tuberculous abscesses
Tuberculomas
Nocardial abscesses
Candidal abscesses
Syphilitic gummas

Progressive multifocal leukoencephalopathy (PML) can cause mental status changes and focal signs, but headache and seizures are unusual. PML lesions themselves cause no mass effect.

Workup

Laboratory Studies

  • Serology
    • Rising serum immunoglobulin G (IgG) titers are observed.
    • An immunoglobulin M (IgM) antibody response is seen in cases of newly acquired toxoplasmosis or Toxoplasma encephalitis.
    • Serologic testing can be falsely negative or noncontributory if levels do not rise from a baseline.
    • Antibody levels may be very low, especially in AIDS patients.
    • In one study, 16% of patients with a clinical diagnosis and 22% of patients with a histologic diagnosis of toxoplasmosis had undetectable anti-T gondii IgG levels.
    • Causes of false-negative results include recent infection and insensitive assays.
  • Lumbar puncture may be contraindicated because of increased intracranial pressure. Cerebrospinal fluid (CSF) findings may include elevated protein and variable glucose and WBC counts. The presence of Epstein-Barr virus DNA in the CSF favors the diagnosis of lymphoma.
  • Identification of T gondii nucleic acids by polymerase chain reaction (PCR) may be helpful in the diagnosis.

Imaging Studies

  • CT scan or MRI
    • Single or multiple hypodense or hypointense lesions in white matter and basal ganglia with mass effects may be observed.
    • Lesions may enhance in a homogeneous or ring pattern with contrast.
    • Imaging studies may be normal in diffuse toxoplasmosis.
    • MRI is more sensitive than CT scan in detecting multiple lesions.
    • Single lesions favor the diagnosis of lymphoma over that of toxoplasmosis. However, while multiple lesions are more common than single lesions in toxoplasmosis, in one study 27% of patients had a single lesion on CT scan. In the same study, 14% had a single lesion on MRI.
    • Thallium Th 201 brain single-photon emission computed tomography (SPECT) may be useful in distinguishing between lymphoma and toxoplasmosis. Lymphoma shows an increased uptake compared with toxoplasmosis. False-positive and false-negative results may occur if the lesion is smaller than 2 cm.

Procedures

  • Indications for brain biopsy include the following:
    • Single mass lesion and negative serologic results
    • No response to 14 days of empiric therapy
  • Diagnostic yield of stereotactic biopsies increases with the number of specimens obtained.

Histologic Findings

  • Lymphocytic meningitis, individual cyst-containing lesions
  • Astroglial and microglial nodules
  • Associated lymphocytic vasculitis
  • Diffuse encephalitis

More on HIV-1 Associated Opportunistic Infections - CNS Toxoplasmosis

Overview: HIV-1 Associated Opportunistic Infections - CNS Toxoplasmosis
Differential Diagnoses & Workup: HIV-1 Associated Opportunistic Infections - CNS Toxoplasmosis
Treatment & Medication: HIV-1 Associated Opportunistic Infections - CNS Toxoplasmosis
Follow-up: HIV-1 Associated Opportunistic Infections - CNS Toxoplasmosis
Multimedia: HIV-1 Associated Opportunistic Infections - CNS Toxoplasmosis
References
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References

  1. AAN Quality Standards Subcommittee. Evaluation and management of intracranial mass lesions in AIDS. Report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. Jan 1998;50(1):21-6. [Medline].

  2. Behbahani R, Moshfeghi M, Baxter JD. Therapeutic approaches for AIDS-related toxoplasmosis. Ann Pharmacother. Jul-Aug 1995;29(7-8):760-8. [Medline].

  3. Bertschy S, Opravil M, Cavassini M, et al. Discontinuation of maintenance therapy against toxoplasma encephalitis in AIDS patients with sustained response to anti-retroviral therapy. Clin Microbiol Infect. 2006;12(7):666-71. [Medline].

  4. Dedicoat M, Livesley N. Management of toxoplasmic encephalitis in HIV-infected adults (with an emphasis on resource-poor settings). Cochrane Database Syst Rev. 2006;3:CD005420. [Medline].

  5. Fung HB, Kirschenbaum HL. Treatment regimens for patients with toxoplasmic encephalitis. Clin Ther. Nov-Dec 1996;18(6):1037-56; discussion 1036. [Medline].

  6. Klepser ME, Klepser TB. Drug treatment of HIV-related opportunistic infections. Drugs. Jan 1997;53(1):40-73. [Medline].

  7. Marra MC. Infections of the central nervous sytem in patients infected with human immunodeficiency virus. Continuum. 2006;12:111-32.

  8. Offiah CE, Turnbull IW. The imaging appearances of intracranial CNS infections in adult HIV and AIDS patients. Clinical Radiology. 2006;61:393-401. [Medline].

  9. Verma A. Neurological manifestations of human immunodeficiency virus infection in adults. In: Neurology in Clinical Practice. Vol 2. 2004:1581-1601.

  10. Walker M, Zunt JR. Parasitic central nervous system infections in immunocompromised hosts. Clin Infect Dis. Apr 1 2005;40(7):1005-15. [Medline].

  11. de Gans J, Portegies P. Neurological complications of infection with human immunodeficiency virus type 1. A review of literature and 241 cases. Clin Neurol Neurosurg. 1989;91(3):199-219. [Medline].

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Further Reading

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Keywords

acquired immunodeficiency syndrome, AIDS, intracellular parasite, Toxoplasma gondii, T gondii, CNS disease in AIDS, HIV infection, complication of HIV, complication of AIDS, advanced HIV infection

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Contributor Information and Disclosures

Author

Niranjan N Singh, MD, DNB, Assistant Professor of Neurology, University of Missouri Columbia
Niranjan N Singh, MD, DNB is a member of the following medical societies: American Academy of Neurology
Disclosure: Nothing to disclose.

Coauthor(s)

Florian P Thomas, MD, MA, PhD, Drmed, Director, Spinal Cord Injury Unit, St Louis Veterans Affairs Medical Center; Director, National MS Society Multiple Sclerosis Center; Professor, Department of Neurology and Psychiatry, Associate Professor, Institute for Molecular Virology, and Department of Molecular Microbiology and Immunology, St Louis University
Florian P Thomas, MD, MA, PhD, Drmed is a member of the following medical societies: American Academy of Neurology, American Paraplegia Society, and National Multiple Sclerosis Society
Disclosure: Nothing to disclose.

Medical Editor

Ronald A Greenfield, MD, Professor, Department of Internal Medicine, Section of Infectious Diseases, University of Oklahoma College of Medicine
Ronald A Greenfield, MD is a member of the following medical societies: American College of Physicians, American Federation for Medical Research, American Society for Microbiology, Central Society for Clinical Research, Infectious Diseases Society of America, Medical Mycology Society of the Americas, Phi Beta Kappa, Southern Society for Clinical Investigation, and Southwestern Association of Clinical Microbiology
Disclosure: Pfizer Honoraria Speaking and teaching; Gilead Honoraria Speaking and teaching; Ortho McNeil Honoraria Speaking and teaching; Wyeth Honoraria Speaking and teaching; Abbott Honoraria Speaking and teaching; Astellas Honoraria Speaking and teaching; Cubist  Speaking and teaching

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Richard J Caselli, MD, Professor, Department of Neurology, Mayo Medical School, Rochester, MN; Chair, Department of Neurology, Mayo Clinic of Scottsdale
Richard J Caselli, MD is a member of the following medical societies: American Academy of Neurology, American Association of Neuromuscular and Electrodiagnostic Medicine, American Medical Association, American Neurological Association, and Sigma Xi
Disclosure: Nothing to disclose.

CME Editor

Selim R Benbadis, MD, Professor, Director of Comprehensive Epilepsy Program, Departments of Neurology and Neurosurgery, University of South Florida School of Medicine, Tampa General Hospital
Selim R Benbadis, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Sleep Medicine, American Clinical Neurophysiology Society, American Epilepsy Society, and American Medical Association
Disclosure: Nothing to disclose.

Chief Editor

Nicholas Y Lorenzo, MD, Chief Editor, eMedicine Neurology; Consulting Staff, Neurology Specialists and Consultants
Nicholas Y Lorenzo, MD is a member of the following medical societies: Alpha Omega Alpha and American Academy of Neurology
Disclosure: Nothing to disclose.

 
 
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