A 45-year-old man with AIDS is admitted to the hospital with a productive cough, fever, and night sweats. An X-ray film of the chest shows an ill-defined area of consolidation at the periphery of the right middle lobe and mediastinal lymphadenopathy. A sputum culture grows acid-fast bacilli. The patient develops severe headache and neck rigidity. Which of the following brain areas is most likely affected by this patient’s infection?

## **Core Concept**
The patient's symptoms suggest a diagnosis of tuberculosis (TB), given the presence of acid-fast bacilli in the sputum culture, productive cough, fever, night sweats, and mediastinal lymphadenopathy. The progression to severe headache and neck rigidity indicates central nervous system (CNS) involvement, specifically **meningitis**, which is a known complication of TB.

## **Why the Correct Answer is Right**
The correct answer, , corresponds to the **basal meninges**. Tuberculous meningitis typically affects the basal meninges, which include the meninges covering the base of the brain. This area is a common site for the accumulation of tuberculous exudate, leading to inflammation and symptoms such as headache, neck rigidity, and altered mental status. The basal meninges' involvement can also lead to cranial nerve palsies and other neurological deficits.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option does not correspond to a typical site for tuberculous meningitis.
- **Option B:** This area is not the most commonly affected site in tuberculous meningitis.
- **Option D:** This option is incorrect as it does not accurately represent the typical location of tuberculous meningitis.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that tuberculous meningitis often presents with a **triad of symptoms**: headache, fever, and neck stiffness. Early diagnosis and treatment are crucial to prevent long-term neurological sequelae. In patients with AIDS, TB is an opportunistic infection that can present atypically, making a high index of suspicion essential.

## **Correct Answer: . Basal meninges**

✓ Correct Answer: A. Base of the brain