An event characterized only by changes in autonomic function, behavior, or respiratory rate other than apnea is referred to as paroxysmal autonomic event, paroxysmal behavioral event, or paroxysmal respiratory event, respectively.
Paroxysmal behavioral events are characterized by staring episodes or episodes of hyperalertness.
Paroxysmal autonomic events are characterized by episodes of flushing and pallor; and sudden changes in heart rate, blood pressure, or intracranial pressure. They are very rare.
Respiratory paroxysmal events are characterized by bouts of rapid or slow breathing.
The term seizure refers to any clinical paroxysmal event believed or proven to be associated with: (1) scalp-recorded or cortically-recorded electroencephalographic seizures, (2) a focal cerebral or cerebellar hemispheric increased isotope uptake by single photon emission computed tomography, or (3) rSO2 fluctuations by scalp recorded near infrared spectroscopy.
The term seizure should not be used for a clinical paroxysmal event believed or proven not to be associated with scalp-recorded electroencephalographic seizures, cortically-recorded cerebral or cerebellar electroencephalographic seizures, focal hemispheric increased isotope uptake by single photon emission computed tomography, or rSO2 fluctuations by scalp recorded near infrared spectroscopy.
The term electroencephalographic seizure refers to any scalp- or cortically-recorded electroencephalographic pattern considered to result from pathological, massive, and repetitive neuronal depolarization. An electroencephalographic pattern recorded from scalp electrodes is interpreted as an electroencephalographic seizure if it is rhythmic; has an electrical field; has a precise onset, body, and offset; and is not considered to be physiologic or artifactual in nature (click on clip).

Most seizures originate from the cerebral cortex but some originate from the cerebellum. The term cerebellar seizures refers to any clinical paroxysmal event believed or proven to be due to pathological, massive, and repetitive cortical cerebellar neuronal depolarization. Cerebellar seizures are characterized by hemifacial contraction (click on clip), head and eye deviation, nystagmus and autonomic dysfunction; consciousness is usually not affected. They occur with cerebellar tumors.

Facial spasms due to cerebellar seizures may be very subtle. Ipsilateral arm contraction is often present (click on clip).

The patient in the last two clips had tuberous sclerosis and a large cerebellar subependymal giant cell astrocytomas (Figure 2.1).

A	B

Figure 2.1.— [A] Sagittal MRI of the brain demonstrating a large posterior fossa tumor (contrast) and dilatation of the third ventricle. [B] Hematoxylin-eosin stain of tumor tissue demonstrating a solid proliferation of large balloon cells with abundant glassy to finely granular or foamy eosinophilic cytoplasm with frequent eccentric uniformly regular nuclei with bland chromatin and a distinct nucleoli. The histology was consistent with a subependymal giant cell astrocytomas.