Differential Diagnosis

The patient's presentation of progressive diffuse headache, generalized malaise, low-grade fever, weight loss, neck stiffness, cranial nerve weakness, and bilateral papilledema, along with the cerebrospinal fluid (CSF) analysis, suggests an infectious or inflammatory process affecting the central nervous system (CNS). The key findings include elevated CSF protein, low glucose, and a lymphocytic pleocytosis, which are indicative of an infectious or inflammatory condition.

• Single Most Likely Diagnosis

  • C) Cryptococcal meningitis: This diagnosis is highly likely given the patient's history of intravenous drug use, which may imply immunocompromised status (e.g., HIV/AIDS), and the presentation of chronic meningitis (progressive headache, malaise, low-grade fever, weight loss). The CSF findings (elevated protein, low glucose, lymphocytic pleocytosis) are consistent with cryptococcal meningitis, a common opportunistic infection in immunocompromised patients.

• Other Likely Diagnoses

  • A) Bacterial meningitis: Although less likely given the chronic nature of the symptoms and the lymphocytic predominance in the CSF, bacterial meningitis can present with similar symptoms and should be considered, especially if the patient's condition deteriorates rapidly.
  • E) Herpes simplex encephalitis: This condition typically presents with more acute symptoms, including fever, headache, confusion, and seizures. However, it can sometimes present with a more subacute course, and the presence of cranial nerve deficits and papilledema could be seen in advanced cases.

• Do Not Miss Diagnoses

  • G) Idiopathic intracranial hypertension: Although the patient's symptoms and CSF findings are not typical for idiopathic intracranial hypertension (IIH), the presence of papilledema and elevated opening pressure on lumbar puncture could suggest IIH. However, IIH typically does not cause low CSF glucose or such a significant pleocytosis.
  • H) Intracerebral hemorrhage: While the CT scan did not show evidence of hemorrhage, the possibility of a small hemorrhage not visible on the CT or a hemorrhage that has been missed due to the timing of the scan should be considered, especially if the patient's condition suddenly worsens.

• Rare Diagnoses

  • I) St. Louis encephalitis: This viral encephalitis can present with similar symptoms but is less common and typically associated with specific geographic and seasonal exposures.
  • D) Glioblastoma multiforme: While a brain tumor could explain some of the patient's symptoms, such as headache and cranial nerve deficits, the CSF findings and the systemic symptoms (fever, weight loss) are not typical for a primary brain tumor.
  • B) Cerebral infarction and F) Hypertensive encephalopathy are less likely given the chronic nature of the symptoms and the specific CSF findings.