Benign Neonatal Sleep Myoclonus

Benign neonatal sleep myoclonus is usually bilaterally symmetrical with involvement of the upper and sometimes lower extremities.

• Limb jerking occurs in clusters during non-REM sleep and repeats at irregular intervals.

• The myoclonic jerks only occur during sleep and never when the infant is fully awake.

• A feature that helps distinguish benign neonatal sleep myoclonus from seizures is that they will abruptly stop when the baby is aroused.

It occurs in otherwise healthy babies with normal development.

• Episodes usually begin within 2 weeks of life.

• It is NOT an epileptic condition and it is NOT associated with epileptiform discharges.

Imaging studies are NOT routinely indicated.

• If an EEG is ordered, do NOT confuse muscle artifacts for interictal spikes.

Reassure the caregivers of the benign nature of the condition.

• Infants “outgrow” their myoclonus within 2 to 3 months.

• Antiepileptic drugs are ineffective in treating the myoclonic jerks and should NOT be prescribed.

Recommended Reading

1. Egger J, Grossmann G, Auchterlonie IA. Benign sleep myoclonus in infancy mistaken for epilepsy. BMJ. 2003 May 3;326(7396):975-6. doi: 10.1136/bmj.326.7396.975. PMID: 12727774; PMCID: PMC1125884.

2. Di Capua M, Fusco L, Ricci S, Vigevano F. Benign neonatal sleep myoclonus: clinical features and video-polygraphic recordings. Mov Disord. 1993 Apr;8(2):191-4. doi: 10.1002/mds.870080213. PMID: 8474488.

3. Walters AS. Clinical identification of the simple sleep-related movement disorders. Chest. 2007 Apr;131(4):1260-6. doi: 10.1378/chest.06-1602. PMID: 17426241.

4. Paro-Panjan D, Neubauer D. Benign neonatal sleep myoclonus: experience from the study of 38 infants. Eur J Paediatr Neurol. 2008 Jan;12(1):14-8. doi: 10.1016/j.ejpn.2007.05.002. Epub 2007 Jun 18. PMID: 17574462.

5. Pediatric Neurology (What Do I Do Now) 2nd Edition by Gregory L. Holmes MD (Author), Peter M. Bingham MD (Author)

Video Lecture

Torsades de Pointes

ECG Findings Explained

Polymorphic Ventricular Tachycardia

Torsades de pointes is a Polymorphic Ventricular Tachycardia. Note that the QRS complexes vary in height, width, shape, and axis.

Twisting of the Pointes

A characteristic finding of torsades de pointes is a recurring reversal of waveform polarity. The gradual alteration in polarity gives the appearance of QRS complexes twisting around the baseline in a spindle-like fashion.

Associations

Torsades de pointes is associated with QTc prolongation. Other common etiologies include electrolyte disturbances (e.g., hypokalemia, hypocalcemia, hypomagnesemia) and medication side effects (e.g., quinidine, amiodarone).

Pitfalls

The rapid and gradual alteration of QRS complexes can be mistaken for ventricular fibrillation. Ventricular fibrillation, however, is completely chaotic without any discernible pattern or similarity between adjacent waveforms.

Summary

The main ECG findings that occur with torsade des pointes include:

• Polymorphism of QRS complexes

• Progressive changes in height, width, shape, and axis

• Recurring reversal of waveform polarity

Video Lecture

Hand and Wrist Injuries

X-ray Quiz