NEET-PG 2021 — Pediatrics

Question 1: A child presents with myoclonic jerks and decreasing school performance. The child had a history of fever and rash at the age of 1 year. What is the most likely diagnosis?

• A. Measles
• B. Subacute sclerosing panencephalitis (SSPE) (Correct Answer)
• C. Mesial temporal sclerosis
• D. Polio

Explanation: ***Subacute sclerosing panencephalitis (SSPE)*** - SSPE is a **rare, progressive, and fatal neurodegenerative disease** caused by persistent measles virus infection of the central nervous system. - The presentation of **myoclonic jerks** (stage 2 SSPE) and **decreasing school performance** (stage 1 - cognitive decline) in a child with a history of measles (fever and rash) at 1 year of age is **pathognomonic** for SSPE. - SSPE typically manifests **7-10 years after measles infection**, with male predominance (M:F = 2-4:1). - EEG shows characteristic **Radermecker complexes** (periodic high-amplitude slow wave complexes). - CSG findings include elevated measles antibodies with high CSF:serum antibody ratio. *Measles* - While the child had measles in infancy, the current neurological symptoms are **not acute measles** but rather a late complication (SSPE). - Acute measles is a self-limiting illness; these progressive neurological symptoms occurring years later indicate SSPE, not active measles. *Mesial temporal sclerosis* - This is the most common cause of **drug-resistant temporal lobe epilepsy** characterized by hippocampal atrophy. - Presents with **focal seizures with impaired awareness**, not generalized myoclonic jerks. - **No link to prior measles infection** and typically associated with history of febrile seizures or status epilepticus in childhood. - Progressive cognitive decline is not a primary feature. *Polio* - Polio is caused by **poliovirus** affecting anterior horn cells of the spinal cord, causing **acute flaccid paralysis**. - Presents with **asymmetric lower motor neuron weakness**, not myoclonic jerks or cognitive decline. - **No association with measles** or rash in history. - Would not cause the progressive encephalopathy seen in this case.