Beyond the Usual Suspicions: Uncovering Meningeal Involvement in Miliary Tuberculosis

Abstract Introduction Central nervous system (CNS) involvement is atypical in tuberculosis (TB) but more likely in miliary cases, underscoring the need for high clinical suspicion. Here, we explore the diagnostic challenges and treatment approach in a unique case of miliary TB, especially given the absence of traditional immunocompromising factors. Case Description A 64-year-old male originally from Sudan with a history of diabetes mellitus and hypertension presented with several weeks of fever, fatigue, malaise, and poor appetite. He had last traveled to Sudan three years prior and had been residing in the United States for 35 years. Upon admission, he was febrile to 101.4°F. Laboratory tests showed mild transaminitis. Imaging studies, including chest X-ray and CT, revealed a thick-walled, solitary cavitary lesion measuring 3.9 x 2.8 cm in the left upper lobe, with prominent surrounding fibrosis and consolidation. There were also marked bronchiectasis, numerous small solid nodules bilaterally, and lymphadenopathy. While undergoing diagnostic workup, the patient's mental status deteriorated, raising concerns for meningitis or encephalitis. However, MRI of the brain did not reveal acute intracranial abnormalities. Bronchoscopic cultures eventually confirmed the presence of Mycobacterium tuberculosis, establishing a diagnosis of miliary tuberculosis. The patient's transaminitis and altered mental status heightened suspicion for TB hepatic and meningeal involvement. Due to the patient's preference, a lumbar puncture could not be performed. Following initiation of RIPE and dexamethasone, the patient experienced significant clinical improvement. Intravenous levofloxacin was initially added due to high blood-brain barrier penetration but later discontinued due to potential risk for toxicity and unclear benefit in CNS TB. Discussion Miliary tuberculosis is an uncommon manifestation, representing about 2% of all TB cases. Although CNS involvement in tuberculosis is rare (around 1% of cases), it is more common in miliary TB, with an incidence of 10% to 30%. This elevated risk highlights the importance of maintaining a high level of clinical suspicion when evaluating such patients. Diagnosing CNS tuberculosis poses substantial challenges; as extrapulmonary lesions are often paucibacillary, microbiological confirmation through cerebrospinal fluid analysis may be inconclusive. Consequently, in cases with high clinical suspicion for CNS infection, initiating empiric therapy is often warranted. Addition of corticosteroids to RIPE may have a mortality benefit in CNS TB while data for adding levofloxacin are less robust. Immunocompromised individuals, including those with advanced age, alcoholism, malnutrition, malignancy, or HIV, are at increased risk for CNS TB. However, none of these risk factors were identified in our patient.