Cerebellar Fits in Children with Chiari I Malformation

Discussion

Jackson ^[8] coined the term "cerebellar fits" in 1871 to describe tetanus-like episodes that occurred in a 5-year-old boy with a midline cerebellar tumor (Fig. 3). The first description of convulsive seizures associated with a cerebellar lesion was reported by Wurffbain in 1691, who described head retraction and opisthotonos in association with a cerebellar tumor.^[5] Cushing ^[2] recognized that a pressure cone across the foramen magnum could result in sudden death.

(Enlarge Image)

. Drawing by Sir Stephen Mackenzie of a child experiencing a tetanus-like seizure. The drawing was included in Hughlings Jackson's case report of a cerebellar tumor in which he coined the term "cerebellar fits."

Cerebellar fits have been discussed infrequently in the recent neurosurgical literature. These paroxysmal spells are characterized by drop attacks with or without loss of consciousness, abnormal extensor posturing, and varying degrees of respiratory compromise. Presumably, cerebellar fits were seen more commonly in the era before modern neuroimaging, when patients with large posterior fossa tumors would present in extremis with cerebellar tonsillar herniation.

Cerebellar fits are not limited to patients with cerebellar tumors, arising likewise in patients with conditions in which there is tonsillar herniation. In our series of children with symptomatic Chiari I malformation, more than 25% experienced paroxysmal drop spells that could be characterized as cerebellar fits. It is important to remember that children with Chiari I malformation can present with drop attacks, abnormal posturing, and apneic spells. Failure to recognize this association can lead to a delay in diagnosis or even misdiagnosis. Chiari I malformation-related cere-bellar fits in children are frequently misdiagnosed initially as epileptic seizures or cardiogenic syncope, and patients have often undergone evaluation with EEG and/or ECG and Holter monitoring before the diagnosis of Chiari I malformation is confirmed on MR imaging.

It is noteworthy that three of our patients with cerebellar fits also had a history of epileptic seizures. Cerebral cortical abnormalities are not generally considered to be part of Chiari I malformation, and we are not sure if this association is significant. The occurrence of true epileptic seizures associated with Chiari I malformation (primarily complex partial fits or paroxysmal abnormalities referable to the frontal or temporal lobes) has been reported previously. ^[4] The course of epilepsy in these affected patients is usually benign. Although some patients with Chiari I malformation may have epilepsy, the major finding in our study was that the tonic posturing seen in Chiari I malformation patients with cerebellar fits can be mistaken for epilepsy and lead to a delay in diagnosis.

In children with cerebellar fits and Chiari I malformation the presentation is an extreme manifestation of brain-stem dysfunction. The most feared consequences of cerebellar fits in this population are respiratory arrest and sudden death. This outcome may be avoided by early diagnosis. Thus, it is important to remember that cerebellar fits in patients with Chiari I malformation can mimic other paroxysmal events such as epilepsy and cardiogenic syncope. The diagnosis of tonsillar herniation can be confirmed using MR imaging. The response of these patients to decompressive surgery is gratifying.

Abbreviations used in this paper: ECG = electrocardicography; EEG = electroencephalography; MR = magnetic resonance.

Neurosurg Focus. 2001;11(1) © 2001 American Association of Neurological Surgeons

Cite this: Cerebellar Fits in Children with Chiari I Malformation - Medscape - Jul 01, 2001.