A 16-year-old girl presents with a first generalized tonic-clonic seizure on waking. She reports morning jerks of both arms for the past year causing her to drop objects, and occasional blank stares. Seizures are triggered by sleep deprivation, alcohol, and flickering lights at a discotheque. Neurological examination and MRI are normal. EEG shows the pattern marked **B** in the diagram—generalized 4–6 Hz polyspike-and-wave discharges with photoparoxysmal response on photic stimulation. Based on this EEG finding and clinical presentation, what is the most likely diagnosis?
A. Juvenile Absence Epilepsy
B. Generalized Tonic-Clonic Epilepsy, Genetic Generalized
C. Juvenile Myoclonic Epilepsy (Janz syndrome)
D. Childhood Absence Epilepsy
Explanation
Why Juvenile Myoclonic Epilepsy (Janz syndrome) is right
The EEG pattern marked B—generalized 4–6 Hz polyspike-and-wave discharges with photoparoxysmal response—is the pathognomonic hallmark of Juvenile Myoclonic Epilepsy (JME). Combined with the classic clinical triad of morning myoclonic jerks (causing her to drop her toothbrush), generalized tonic-clonic seizures on waking, and absences (blank stares), and the characteristic triggers (sleep deprivation, alcohol, flickering lights), the diagnosis is definitive. JME accounts for ~10% of all epilepsies and is a generalized genetic epilepsy with genetic loci including GABRA1 and EFHC1 (Harrison's 21e, ILAE 2017 Classification).
Why each distractor is wrong
Childhood Absence Epilepsy: Presents with frequent brief absences (10–20 per day) in younger children (3–8 years), NOT morning myoclonic jerks or generalized tonic-clonic seizures. EEG shows 3 Hz spike-and-wave (not 4–6 Hz polyspike-and-wave), and photoparoxysmal response is absent.
Generalized Tonic-Clonic Epilepsy, Genetic Generalized: This is an umbrella category that includes JME, but it does not explain the specific EEG pattern (B) or the morning myoclonic jerks. The diagnosis requires the specific polyspike-and-wave pattern and myoclonic component.
Juvenile Absence Epilepsy: Presents with frequent absences and generalized tonic-clonic seizures but lacks the prominent morning myoclonic jerks that define JME. EEG shows 3 Hz spike-and-wave, not the 4–6 Hz polyspike-and-wave pattern marked B.
High-YieldNEET PG
JME = morning myoclonic jerks + 4–6 Hz polyspike-and-wave + photoparoxysmal response + triggers (sleep deprivation, alcohol, flashing lights) = valproate (avoid in women of childbearing age; use levetiracetam or lamotrigine instead) and lifelong treatment (>80% relapse on withdrawal).
Harrison's 21e Epilepsy; ILAE Classification 2017
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