Imipramine overdose Extemal ophthalmoplegia and alpha and spindle coma

A 13-year-oid boy was admilted to hospital after the ingestion of 1000mg of imipramine. He developed seizures, respiratory arrest and coma and required intubation. A toxic screen revealed a serum imipramine level of 1021 Ilg/ml (therapeutic level 150 ltg/mil and a desipramine level of 420 Ilg/ml (therapeutic level 100 Itgl ml):Oculocephalic reflexes were absent. Electroencephalograph (EEG) patterns on admission exhibited an invariant pallern of diffuse lO-12Hz waves with anterior predominance unreactive to stimuli On the third hospital day the previous alpha-coma EEG pattern had evolved into a spindle-coma pattern with random or sequential delta waves on which spindles at lO-12Hz were superimposed On the sixth hospital day wtlen serum Imipramine had dropped to. 40 mg/ml the boy showed fluctuating alertness and nystagmus on gaze in all directions. Prolonged brain stem auditory evoked potentials also normalised as coma and oculocephalic reflex abnormalities resolved. Eight days after admiSSion the patient was fully recovered and the neurological examination shawe.d. on aly:\nr.r;r) I;!.MiR.~.

Impaired oculovestibular function In

tricyclic overdose may be the result of the peripheral aclion ot the drug on the eighth cranial nerve or a central action on brainslem neurones, It is suggested Iha! the changing EEG patterns from alpha to spindle-coma may have been caused by selective suppression of brain stem function by varying levels of the drug.

The absence of reflex eye movements In a comatose patient , and the presence of alpha- and spindle-coma EEG patterns wllh prolonged brain stem auditory evoked potentials do not seem to be reliable prognostiC indicators in tricyclic drug overdose P1llst S.M and Lombroso. C T Annals 01 NeuroJogy 14. 581 (Nov 1983)

8 Reactions 10 Mar 1984 0157-7271 /84 / 0310-0008 / 0$01.00/ 0 © AD/S Press