A 45-year-old man comes to the emergency department due to 3 weeks of headache and malaise and a week of double vision, vomiting, and fever. Medical history is significant for alcohol use disorder. Temperature is 38.3 C (100.9 F), blood pressure is 140/90 mm Hg, pulse is 88/min, and respirations are 14/min. Mild lethargy is present. Examination shows neck stiffness and lateral deviation of the right eye with impaired adduction. Noncontrast CT scan of the head is normal. Laboratory results are as follows:
| Cerebrospinal fluid | |
| Glucose | 25 mg/dL |
| Protein | 180 mg/dL |
| Red blood cells | 0/mm3 |
| Leukocytes | 400/mm3 |
| Neutrophils | 30% |
| Lymphocytes | 70% |
Serum HIV testing is negative. What is the most likely diagnosis?
Cerebrospinal fluid analysis | |||
Diagnosis | WBC count | Glucose | Protein |
Normal | 0-5 | 40-70 | <40 |
Bacterial | >1,000 | <40 | >250 |
Tuberculous | 100-500 | <45 | 100-500 |
Viral meningitis | 10-500 | 40-70 | <150 |
Guillain-Barré | 0-5 | 40-70 | 45-1,000 |
WBC = white blood cell. | |||
This patient's subacute symptoms, nuchal rigidity, cranial nerve palsy (impaired adduction and lateral deviation of eye), and cerebrospinal fluid (CSF) findings are consistent with tuberculous (TB) meningitis. TB meningitis occurs in 5% of patients with extrapulmonary TB, but risk is increased in those with impaired immune function due to alcohol use disorder, substance use disorder, malnutrition, immunomodulatory medications, or HIV. Although TB forms an initial nidus of infection in the lungs, most patients with TB meningitis have no pulmonary symptoms.
Because Mycobacterium tuberculosis replicates slowly, TB meningitis tends to present with weeks of progressive headache, nausea/vomiting, fever, neck stiffness, and malaise. The inflammation can affect the basal portion of the brain, with pressure from the resulting dense gelatinous exudate often causing cranial nerve palsy. Although imaging with contrast usually shows basal meningeal enhancement and small strokes (from tuberculous vasculitis), noncontrast head CT is sometimes normal (as in this case). CSF analysis generally shows lymphocytosis with a leukocyte count of 100-500/mm3, mild protein elevation, low glucose, and elevated adenosine deaminase. Acid-fast bacilli stain or nucleic acid amplification testing of CSF can provide rapid diagnosis, but culture is required for confirmation.
(Choice A) Herpes encephalitis is associated with acute (<1 week) fever, headache, focal neurologic deficits, confusion, and/or seizures are present. CSF analysis often shows lymphocytosis and elevated protein, but most patients have high CSF red blood cell counts.
(Choice B) Meningococcal meningitis is marked by severe myalgias, petechiae, fever, headache, and nausea/vomiting. It progresses within hours (not weeks) to septic shock and death. CSF analysis shows dramatic white blood cell count elevation with neutrophil predominance and high protein.
(Choice C) Neurocysticercosis is caused by ingestion of ova of the pork tapeworm Taenia solium. This disease usually presents years after initial infection with seizure (primarily) or focal neurologic deficits. Fever is uncommon.
(Choice D) Subarachnoid hemorrhage usually presents with severe, acute headache. Although noncontrast head CT is often diagnostic, a minority of patients have normal initial imaging. However, CSF analysis will show significant red blood cells that do not diminish in quantity as successive vials are collected (eg, similar quantities in vial 1 and vial 4).
Educational objective:
Tuberculous meningitis is generally marked by subacute symptoms of meningeal irritation with or without cranial nerve palsy and stroke. Cerebrospinal fluid analysis generally reveals lymphocytosis, moderate increase in white blood cells, mildly elevated protein, low glucose, and elevated adenosine deaminase.