Neonatal Seizures – Not a Benzo Deficiency!
We are all rather accustomed to managing the patient who is having a seizure. ABCDs… Airway, Breathing, Circulation, and Disrobe… and then Benzos if there is still shaking. This method works pretty well. But one population that deserves some specific attention is the neonate who is having a seizure. As is often the rule, “don’t trust a neonate!”
a) Neurological dysfunction in a neonate is frequently demonstrated by neonatal seizures.
i) Incidence is estimated at ~3 / 1,000 live births
ii) Pre-term neonates have a much higher incidence (57 to 132 / 1,000 live births)
iii) Most (80%) occur in the first days to week of life.
b) Neonatal Seizures can be difficult to recognize clinically!
i) Generalized tonic-clonic acivity is not common.
ii) There will be no recognizable post-ictal state (they kind of live in a post-ictal state at that age – so you wouldn’t notice any difference).
iii) Usually subtle – so before you dismiss the parental concern, listen carefully… and observe!
(1) Subtle Sz (50%)
(a) Often overlooked
(b) Can be misconstrues as normal behaviors and reactions.
(c) Ocular movements, oral-buccal-lingual movements, progression movements (ex. rowing, swimming, pedaling, thrashing), Complex Purposeless Movements.
(2) Clonic Sz (25%)
(a) Rhythmic jerking
(b) Todd’s Paresis can follow prolonged hemiconvulsions.
(3) Myoclonic Sz (20%)
(a) Rapid, single or arrhythmic repetitive jerking.
(b) May mimic the Moro reflex.
(c) Myoclonic Sz is associated with the most severe brain damage; however, can also occur in healthy neonates with abundant myoclonic movements occurring during sleep.
(4) Tonic Sz (5%)
(a) Sustained contraction.
(b) May be focal, multifocal, or generalized.
(c) May mimic decerebrate or decorticate posturing.
c) Etiologic Considerations
(1) Ok, so this isn’t actually the most common cause, it is still the one that we must consider first in our initial evaluation!
(2) Meningoencephalitis must be excluded in all neonates with seizures.
(3) In addition to GBS, E.Coli, and Listeria, don’t forget TORCHeS, which can present as seizures.
ii) Hypoxic-Ischemic Encephalopathy (HIE)
(1) Most common cause
(2) Most Sz due to HIE manifest within the first 48hrs of life.
iii) Intracranial Hemorrhage
(1) Intraventicular and periventricular hemorrhage (particularly Preterm kids)
(2) Subarachnoid, intraparenchymal, or Subdural more common in Term kids.
(3) May occur “spontaneously” or from trauma (consider NAT always).
(1) Hypoglycemia, hypocalcemia, hypomagnesemia are most common metabolic causes.
(2) Inborn Errors of Metabolism (ex, amino acid and organic acid disorders, hyperammonemias) can also lead to these derangements and subsequent seizures.
(3) Pyridoxine deficiency should also be considered.
(1) Cerebral malformations
(2) Drug withdrawal and toxicity (ex, maternal narcotics, intrapartum maternal medications, inadvertent local anesthetic injection into the neonates scalp)
(3) Neurocutaneous syndromes (ex, tuberous sclerosis)
vi) NOTE: just because you found one possible etiology, does not mean that another doesn’t exist concurrently. Hypoglycemia may be present along with meningitis. So, do not waver from your initial concern for meningitis when you find out the glucose is 20. Naturally, treat the glucose, consider other inborn errors of metabolism… then perform the LP and give antibiotics.
d) A “rational, initial evaluation” – at least I think so.
i) Thorough H+P (naturally… but seriously, look for bulging fontanel, pt’s tone, signs of abuse, dysmorphic characteristics, HSM, rashes, genital exam, etc!)
ii) Obtain serum electrolytes with glucose, calcium, magnesium, and phosphorus.
iii) Obtain CSF (even if the electrolytes return abnormal).
(1) Cranial Ultrasound can be done first. It is excellent at showing intraventricular and parenchymal hemorrhage, but cannot detect SAH or SDH.
(2) Head CT or MRI can also be performed (although I’d favor CT while in the ED).
v) You may want to draw and hold extra blood for further inborn errors of metabolism work-up.
vi) Admit for EEG and further management and monitoring.Panayiotopoulos CP. Chapter 5: Neonatal Seizures and Neonatal Syndromes in The Epilepsies: Seizures, Syndromes, and Management. Bladon Medical Publishing; 2005.