What investigations should be done in a case of seizures in a child under post-ictal (after seizure) drowsiness for 30 minutes?

Investigations for Post-Ictal Drowsiness in a Child After Seizure

Immediate Assessment

In a child with post-ictal drowsiness lasting 30 minutes after a seizure, the primary investigation should be blood glucose measurement, while most other routine laboratory tests and neuroimaging are not indicated unless specific clinical red flags are present. 1

Blood Glucose Testing

• Measure blood glucose immediately in any child who remains somnolent or has altered mental status after a seizure, as hypoglycemia is one of the few immediately treatable metabolic causes 1
• Serum sodium should also be obtained alongside glucose, as these represent the only commonly treatable metabolic abnormalities requiring urgent identification 1
• However, hypoglycemia as a cause of pediatric seizures is extremely rare (0.5% in one large series), so glucose testing is most critical when mental status remains impaired 2

When Neuroimaging is NOT Needed

• Routine neuroimaging (CT or MRI) is not indicated for post-ictal drowsiness alone if the child returns to baseline within several hours 3, 1
• The American College of Radiology specifically states that post-ictal drowsiness lasting 30 minutes does not constitute an indication for emergent imaging 3
• For simple febrile seizures, no imaging or laboratory workup is required in the absence of other neurological signs 1

Red Flags Requiring Emergent Neuroimaging

Obtain emergent CT head without contrast if any of the following are present: 3, 1

• Post-ictal focal neurological deficit that does not quickly resolve
• Failure to return to baseline mental status within several hours (not just 30 minutes)
• Signs of increased intracranial pressure
• History of significant head trauma
• Concern for intracranial hemorrhage or mass effect

Additional Investigations Based on Clinical Context

For Febrile Seizures:

• No routine laboratory tests or imaging are needed for simple febrile seizures (generalized, <15 minutes, single episode) 1, 4
• Consider lumbar puncture only if clinical signs suggest meningitis or encephalitis, not for post-ictal drowsiness alone 3, 5

For Complex Febrile Seizures:

• EEG should be obtained (not emergently) as these children have increased epilepsy risk 4
• Neuroimaging remains unnecessary unless specific red flags exist 3, 4

For First Unprovoked Seizures:

• Blood pressure measurement is essential in all cases 5
• Consider additional metabolic workup (electrolytes, calcium, magnesium) only if history or examination suggests specific abnormalities 3, 1
• MRI brain without contrast is preferred over CT for non-emergent evaluation, particularly with focal features or abnormal neurological examination 1

Common Pitfalls to Avoid

• Do not order routine laboratory panels (complete metabolic panel, CBC, etc.) based solely on seizure occurrence—these should be guided by specific clinical indicators from history and examination 3, 1
• Do not obtain emergent neuroimaging for typical post-ictal drowsiness lasting 30 minutes, as this is an expected normal finding after seizures 3
• Do not perform lumbar puncture routinely for post-ictal drowsiness; reserve this for clinical suspicion of CNS infection based on fever, meningeal signs, or other concerning features 5
• Creatine kinase (CK) elevation is common after generalized tonic-clonic seizures but does not require routine measurement unless rhabdomyolysis is suspected clinically 6

Observation Period

• Most children should be observed until they return to baseline mental status 3
• If baseline is not reached within 5-10 minutes after seizure activity stops, activate emergency medical services 3
• Post-ictal periods typically last several minutes; drowsiness persisting beyond several hours warrants emergent imaging 3