Paroxysmal events are common in the neonate. It is not always easy to tell if these episodes are epileptic seizures because ERG discharges may not always be seen in epileptic seizures at this age.
Non-epileptic events
Benign neonatal sleep myoclonus
If the physician is not able to observe an episode of this common condition then video recording is the only necessary investigation. If home videocamera or mobile phone filming is not possible, then the parents may be shown video recordings of known examples to confirm, "That's it."
Flurries of multiple flexion jerks in long runs are seen in sleep. EEG is not indicated but if ictal EEG is carried out it is most important to avoid misinterpreting rhythmic artefacts as epileptic discharges. Bear in mind that as with other non-epileptic events benign neonatal sleep myoclonus may be seen in newborn infants who are not entirely 'normal', and is common in neonatal abstinence syndrome.
Hyperekplexia
In a neonate with some combination of tremulousness, stiffness, and cyanotic attacks (with high voltage runs of EMG 'artefact' on ictal EEG and ECG traces and with head retraction on tapping the tip of the nose and auditory startle, then UNA for analysis in a specialized laboratory is indicated.
Most cases are due to mutations in the gene for the alpha subunit of the strychnine-sensitive glycine receptor (GLRM1) or in that for GIyT2, the postsynaptic glycine transporter (SLC6A5).
Paroxysmal extreme pain disorder
Video recording of the paroxysmal autonomic manifestations, in particular the Harlequin sign, may be helpful to share with others experienced in this disorder. .SCN9A mutations may be analysed in a specialized laboratory.
Seizures (of presumed epileptic mechanism)
Initial investigations by a neonatologist will depend upon the clinical scenario. Cranial ultrasound will detect gross structural lesions. MRI will detect more, including the acute cerebral ischaemia (arterial or venous) most easily seen with diffusion-weighted imaging (DWT). When a cause is not thereby apparent then further investigations will be necessary, often simultaneously performed. What we say below refers to difficult, refractory, unexplained seizures of epileptic type.
Early investigations for rare treatable disorders
( Also see Investigations in rare treatable disorders )
Pyridoxal phosphate trial
Cessation of seizures will indicate either pyridoxal phosphate responsiveness or pyridoxine-dependent epilepsy. Confirmation of pyridoxine-dependent epilepsy will be bv finding α-AASA in blood and urine, followed by mutation analysis of the ALDH7A1 (antiquitin) gene. In pyridoxal-5'-phosphate-responsive seizures due to pyridox(am)ine phosphate oxidase (PNPO) deficiency there may be elevated threonine and glycine in plasma and CSF (and possibly reduced CSF homovanillic acid and 5-hydroxyindole acetic acid). CSF pyridoxal-5'-phosphate will also be reduced. Confirmation is by mutation analysis of the PNPO gene.
