When should you perform an LP?
The short answer – not often. Kimia et al studied patients with first simple febrile seizures and noted that no patients out of their 704 had meningitis – even those with elevated CSF wbc counts. Interestingly this study also chronicled changes in practice. The LP rate declined greatly during the course of the study. Kimia et al then looked at complex febrile seizures. 64% of their 526 patients had an LP. Three had bacterial meningitis (two with S. pneumo in the CSF, and one had S. pneumo on blood culture after a failed LP). Overall LP seems to have limited utility in simple or complex. You should consider doing one if:
- Obvious signs or symptoms of meningoencephalitis
- Age 6-12 months if unvaccinated (especially against S. pneumo and/or HiB)
- If the patient is currently on antibiotics
How about CT scans in the ED?
Ignoring for a moment that many children with recurrent febrile seizures, especially complex ones will eventually see a pediatric neurologist and get an MRI, let’s focus on the ED course and whether or not imaging is warranted. I suggest that you scan very rarely, and only in the cases of:
- Suspected trauma (especially of the non-accidental variety)
- Focal seizure and no return to usual baseline by 2-3 hours
- Evidence of elevated intracranial pressure or mass effect on exam
- History of CNS abnormality (VP shunt etc,.)