A child with Tubercular meningitis (TBM) presents with hydrocephalus after VP shunt has polyuria and hyponatremia. The most probable diagnosis is:
**Core Concept**
Tubercular meningitis (TBM) can lead to hydrocephalus, and the subsequent placement of a ventriculoperitoneal (VP) shunt can cause complications. In this scenario, the child presents with polyuria and hyponatremia, which suggests an abnormality in the regulation of water and electrolytes.
**Why the Correct Answer is Right**
The correct answer is related to the syndrome of inappropriate antidiuretic hormone secretion (SIADH). SIADH is a condition where there is an excessive release of antidiuretic hormone (ADH), leading to water retention and hyponatremia. In the context of TBM, the inflammation and damage to the hypothalamic-pituitary axis can disrupt the normal regulation of ADH, leading to SIADH. The VP shunt, which allows cerebrospinal fluid to drain into the peritoneal cavity, can also contribute to the development of SIADH by allowing the inappropriate release of ADH into the systemic circulation.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the scenario described, as it does not explain the development of polyuria and hyponatremia in a child with TBM and a VP shunt.
* **Option B:** This option is incorrect because it does not account for the presence of polyuria, which is not typically seen in SIADH. In SIADH, patients usually present with water retention and hyponatremia, not polyuria.
**Clinical Pearl / High-Yield Fact**
In patients with TBM and a VP shunt, it is essential to monitor for SIADH, as it can lead to severe hyponatremia and other complications. The use of a urine osmolality and serum sodium level can help diagnose SIADH, and treatment typically involves fluid restriction and sometimes the use of vasopressin receptor antagonists.
**Correct Answer:** C. Syndrome of inappropriate antidiuretic hormone secretion (SIADH).