Epilepsy syndromes by age — formative SAQs

SAQ 1 (10 marks)

A 7-month-old boy is brought in because for two weeks he has had clusters of brief symmetric jerks on waking, each lasting one to two seconds, sometimes twenty or thirty at a time, in which he flexes at the neck and trunk. His mother says he has stopped babbling and reaching for toys in the same period. His interictal EEG shows a chaotic, high-voltage, asynchronous background with multifocal spikes. Skin examination under Wood's lamp is normal. ^{[2] [5]}

1. Name the syndrome and state the diagnostic triad. (3) ^[2]
2. Outline your immediate management, including the first-choice treatment and the timing rationale. (4) ^[5]
3. Describe the role of aetiology in prognosis and how you would investigate the cause. (3) ^{[2] [5]}

Model answer — SAQ 1

(1) Syndrome and triad (3). This is West syndrome (infantile spasms), the archetype of a developmental and epileptic encephalopathy. The diagnostic triad is epileptic spasms occurring in clusters on waking, hypsarrhythmia on the EEG (the chaotic, high-voltage, asynchronous pattern with multifocal spikes), and psychomotor regression or developmental delay — here the loss of babbling and reaching. The peak age of onset is four to eight months. ^[2]

(2) Immediate management (4). I would confirm the diagnosis with video-EEG capturing a spasm cluster if possible, and then start first-line treatment promptly. First-line is vigabatrin or hormonal therapy (ACTH or high-dose oral prednisolone). Because the skin examination is normal and there is no clinical evidence of tuberous sclerosis, I would favour hormonal therapy, which the Cochrane review found more effective than vigabatrin for short-term spasm cessation in non-tuberous-sclerosis cases. The timing rationale is that time-to-treatment is a major determinant of developmental outcome: the epileptic encephalopathy itself drives the regression, so resolving the hypsarrhythmia is treatment of the developmental problem, not just the seizures. I would refer urgently to paediatric neurology. ^[5]

(3) Aetiology and investigation (3). Aetiology is the strongest determinant of prognosis: cryptogenic or unknown-cause cases treated early have a better cognitive outcome than those with an identified structural or genetic cause. I would investigate the cause with a skin examination for tuberous sclerosis (vigabatrin is first-line if present), an MRI brain to look for structural malformation or injury, and genetic testing — initially a gene panel or, increasingly, whole-exome sequencing — because monogenic causes (including CDKL5, STXBP1 and ARX) account for a substantial proportion. Metabolic studies would be guided by any suggestive features. ^{[2] [5]}