Tuberculosis

Q: What is the predominant organism responsible for tuberculosis, and what other organism can also cause it?  show answer

A: The organism Mycobacterium tuberculosis predominantly causes tuberculosis. However, a small proportion of tuberculosis cases occur due to Mycobacterium bovis. 

Q: At what CD4+ count range do Mycobacterium tuberculosis infections become clinically apparent in HIV patients?  show answer

A: Mycobacterium tuberculosis infections become clinically apparent in HIV patients when CD4+ counts drop below 350 cells/mm3, Typically with findings of post-primary pulmonary tuberculosis. 

Q: What are the typical radiological findings in patients with post-primary pulmonary parenchymal tuberculosis? show answer

A: The radiological findings in parenchymal tuberculosis include patchy, poorly defined consolidation, often in the upper lobes, and cavities with thick walls that become smooth with treatment. Tree-in-bud opacities indicate active tuberculosis. Bilateral involvement is common. Successful treatment resolves consolidations and cavities but may lead to scarring changes. 

Q: What is the most common presentation of intracranial tuberculosis? show answer

A: The most common presentation of intracranial tuberculosis is tuberculous meningitis, which predominantly involves infection of the leptomeninges - pia mater and arachnid mater that envelop the brain and spinal cord. Tuberculous meningitis characterizes by Mycobacterium tuberculosis infiltration into the cerebrospinal fluid (CSF) within the subarachnoid space, leading to inflammation and subsequent neurological manifestations. However, tuberculosis can infrequently affect the dura mater, referred to as tuberculous pachymeningitis. The distinction between tuberculous meningitis and tuberculous pachymeningitis is essential as their clinical presentations, management approaches, and outcomes may differ. 

Q: What are the clinical manifestations and cerebrospinal Fluid (CSF) findings associated with tuberculous meningitis? show answer

A: Meningitis is a severe tuberculosis condition that leads to high mortality in affected patients. Tuberculous meningitis presents with prodromal symptoms of low-grade fever and headache, followed by fever, headache, vomiting, and neck stiffness, associated with cranial nerve palsies, explicitly involving the third, fourth, and sixth nerves, and more severe neurological manifestations, including seizures, focal neurological deficits, stupor, and coma. CSF analysis is crucial in diagnosing tuberculous meningitis, revealing lymphocytosis, increased protein levels, and decreased glucose levels. The combination of these clinical manifestations and the characteristic CSF findings aids in diagnosing tuberculous meningitis. 

Q: What are the typical MRI findings in tuberculous meningitis, specifically concerning T1-weighted post-contrast imaging?  show answer

A: In tuberculous meningitis, the typical MRI findings on T1-weighted post-contrast images include diffuse basal enhancement of the meninges in the basal cisterns and along the brain’s convexity, associated with enhancing exudates within the subarachnoid space. These findings reflect the inflammatory changes and fluid collections within the meninges and subarachnoid space. 

Q: What are some of the possible complications associated with tuberculous meningitis? show answer

A: Possible complications of tuberculous meningitis include progressive hydrocephalus, vasculitis, infarction, and cranial neuropathies, which can be present in radiological imaging. 

Q: What are the differential diagnoses to consider when evaluating imaging findings in a suspected case of tuberculous meningitis?  show answer

A: When evaluating imaging findings in a suspected case of tuberculous meningitis, several differential diagnoses should be considered, including pyogenic meningitis, fungal meningitis, neurosarcoidosis, leptomeningeal carcinomatosis, rheumatoid arthritis, and disseminated oligodendroglial-like leptomeningeal tumor of childhood.