Benign Nonepileptic Infantile Spasms Benign Myoclonus of Early Infancy and Shuddering

We conclude this section on Miscellaneous Neurologic Events with a disorder that is most important in the differential diagnosis of epileptic infantile spasms. We were tempted to have placed it in Psychological Disorders next to Gratification (Including Infantile Masturbation) and Stereotypies, but as we shall see there are hints that it may sometimes be a marker of deviant nervous system development, albeit to a very mild degree.

In the first description (147) and in the most recent publications (148, 149) this has been called "benign myoclonus of early infancy", but we agree with Charlotte Dravet and her colleagues (150) that a much better term is "benign nonepileptic infantile spasms". This is because the repetitive axial and limb muscle contractions last longer than myoclonus and are easily misdiag-nosed as epileptic infantile spasms (149). The distinction is that in benign nonepileptic infantile spasms the EEG is normal not only interictally, but during the runs of spasms as well.

Shuddering attacks (151) have been regarded by some authors as a separate condition that may sometimes be an early manifestation of essential tremor (152), but we agree with Kanazawa (153) that shuddering attacks and benign myoclonus of early infancy and benign nonepileptic infantile spasms are all the same thing. A difficulty may be that most physicians have not seen such video recordings which have only rarely been published (148). A case study (case study 9) illustrates the emotional harm that may be done by a precipitate diagnosis of epileptic infantile spasms or West syndrome.

Case study #9. An otherwise normal male infant was referred to the authors' institution at the age of 6 months, with a 1 month history of daily episodes now increasing in frequency. Now three to four times daily he would have a series of clusters of spasmodic extensions of the upper limbs with flexion of his neck and stiffening of his lower limbs. During these runs of spasms he would seem unresponsive although his eyes were open with some upward deviation of the globes. His pediatrician witnessed an episode of serial spasms and thought the appearance typical of infantile spasms (as did renowned paediatric neurologists and epileptologists when video record ings were shown at international meetings in due course). West syndrome was discussed with the parents, who formed the impression that their baby's chance of eventual normal intellect was no more than 10% and were much distressed.

It was notable on detailed questioning that episodes initially occurred only when he was in his high-chair at feeding time, and later when the boy was in his car seat, sitting in a shopping trolley, or sitting on the floor. By the time of his referral to us these serial spasms occurred during every meal, at breakfast, lunch, tea, and dinner. They were never seen when he was lying in bed or standing up. His mother felt that she could prevent or stop the episodes by clapping or talking to him. She thought they were more likely if he was exhausted or exasperated or if his food did not come in time.

Video recording of episodes in his high-chair showed repeated bowing of his head with eyes up, upper limbs outstretched with fists clenched, and lower limbs rigid. The run of spasms ceased when he was given a biscuit and he smiled. Simultaneous EEG showed no ictal complexes, and interictal EEG was also normal.

Episodes gradually lessened and ceased spontaneously at the age of 13 months. Now a schoolboy of 10 years, he has no problems at all. There is no family history of essential tremor.

Of course epileptic infantile spasms may occur in the context of normal development, but the clue to the correct diagnosis of nonepileptic infantile spasms lay in the setting and provocation. Episodes in the high-chair and in the car seat closely resemble the history in cases of infantile masturbation (78) and suggest a similar behavioural mechanism, and not a precursor of essential tremor. Such subtleties add to the richness of the Child Neurologist's work, with no prospect of closure in the foreseeable future.

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Responses

  • taija
    Are infantile spasms only when laying?
    8 years ago
  • marco kr
    Is non myoclonus same as shuddering attacks?
    6 years ago

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