Figure 233

Magnetoencephalography (MEG) studies from two patients with rolandic epilepsy (left two columns) and a patient with Panayiotopoulos syndrome (right two columns). In rolandic epilepsy, equivalent current dipoles of spikes are located and concentrated in the rolandic regions and have regular directions. In Panayiotopoulos syndrome, equivalent current dipoles of spikes are located and concentrated bilaterally in the rolandic regions and right occipital area. The directions of each equivalent current dipole in each area are quite regular as if three small round toothbrushes are placed in each of the three areas. Small yellow circles represent locations and yellow arrows represent directions of equivalent current dipoles. Blue circles and arrows represent bilateral somatosensory evoked magnetic field. Figure courtesy of Dr. Osamu Kanazawa.

Panayiotopoulos syndrome can be defined as an idiopathic benign focal seizure disorder of childhood manifested with autonomic seizures, which are usually infrequent and often single. Characteristically, seizure semiology includes emetic symptoms, which may be combined with other autonomic features. Syncopal-like episodes may occur. Seizures are often prolonged (autonomic status epilepticus). Interictal EEG shows focal high amplitude sharp and slow wave complexes that, in serial EEGs, shift between various EEG electrodes.

Epidemiology (47, 50, 54, 59). Panayiotopoulos syndrome can start as early as 1 year of age or as late as 14 years of age. However, 76% of cases begin between 3 and 6 years of age and onset peaks at 4 to 5 years of age. It affects boys and girls equally. In those children with epilepsy who are 1-15 years old, prevalence is estimated to be 6%, rising to 13% in those 3-6 years old. Therefore, a clinician might expect to see at least one case of

Panayiotopoulos syndrome for every three cases of rolan-dic epilepsy.

Clinical Manifestations (47,50,54,56,57,59-65). Panayiotopoulos syndrome, being idiopathic, is expected to occur in children who are otherwise normal. Two-thirds of seizures occur during sleep, including daytime naps. No precipitants can be identified, although it has been noted that seizures appear to be particularly likely while traveling.

Seizures usually begin with emetic symptoms. These include one or more of nausea, retching, and vomiting. If asleep at seizure onset, the child may be found in bed retching or vomiting. However, many will first waken and complain of nausea. Seizures that occur when awake usually begin with a complaint of nausea often accompanied by behavioral changes, particularly agitation. During the seizure the child commonly vomits a few times; but occasionally vomiting may be repeated many times, sometimes over hours. Seizures in Panayiotopoulos syndrome without at least one feature of the "emetic triad" are rare but do occur.

Other autonomic features may occur concurrently with or follow the emetic features. Pallor is very common; cyanosis and flushing are less common (50). Pupillary abnormalities, especially mydriasis but also miosis, are frequently noticed by eyewitnesses, but will usually require prompting to obtain a report of them. Urinary and occasionally fecal incontinence may occur. A raised temperature may be suspected or measured during or immediately after a seizure and may represent a true ictal symptom, rather than being a precipitant of the seizure. Rarer ictal symptoms that have been reported include headache and other "cephalic sensations," hypersaliva-tion, and coughing (50, 59).

Once it was realized that autonomic features dominated the seizures of Panayiotopoulos syndrome, it was natural to ask whether respiratory and cardiovascular irregularities might occur and, if so, whether these might be dangerous. Breathing changes are sometimes reported, particularly before convulsions (50). Tachycardia is certainly a feature of seizures recorded on EEG with simultaneous ECG recording (50, 66). Cardiorespiratory arrest during a typical seizure of Panayiotopoulos syndrome has been reported (67), and three other children with a diagnosis of Panayiotopoulos syndrome are also suspected to have had cardiorespiratory arrest (50).

When seizures occur in the awake state (or if the child awakens at the start of the seizure), the initial seizure symptoms usually occur in full consciousness (simple focal seizure). However, and after a variable time, consciousness usually becomes impaired (complex focal seizure), although some awareness and ability to respond is often retained. Some observers report behavioral changes such as restlessness, agitation, and terror, apparently in full consciousness (50, 59).

Some seizures in Panayiotopoulos syndrome include features suggestive of syncope, with the child becoming pale, flaccid, and unresponsive (50). Often these features occur along with more typical ones, but can occasionally occur in isolation. The term "ictal syncope" or "ictal syn-copal-like episodes" have been used to denote these (50, 51, 53). It is not known if they are a result of transient hypoperfusion of the brain as in a true syncope.

When Panayiotopoulos syndrome was first described, ictal deviation of the eyes and often also the head were reported as prominent features. Reevaluation of the data has confirmed that such versive features are common. However, they usually occur around the time consciousness is becoming impaired, rather than at the start of the seizure.

Seizures in Panayiotopoulos syndrome often end in hemiconvulsions (around one-fifth of seizures) or GTCS (also around one-fifth of seizures).

An important feature of the seizures is that they are generally prolonged. Of those reported in the literature, 44% lasted for 30 minutes or more (maximum reported is 7 hours). These episodes, therefore, represent a form of nonconvulsive status epilepticus and might reasonably be classified as autonomic status epilepticus. They may end spontaneously or as short hemiconvulsions or GTCS. The child is expected to have returned to normal within a few hours of such episodes. Convulsive status epilepticus is exceptional. The mean duration of nonstatus seizures in Panayiotopoulos syndrome is around 9 minutes.

EEG Features (47, 50, 54-57, 59-65). The interictal EEG of Panayiotopoulos usually shows a normal background with high amplitude sharp and sharp and slow wave foci (functional spikes), similar in morphology if not location to those seen in rolandic epilepsy. Previously the occipital location of these was emphasized, along with their occurrence in long trains (occipital paroxysms) and abolition by central fixation (fixation-off sensitivity). It now appears that these features were overemphasized, and in Panayiotopoulos syndrome the characteristic functional spikes can occur in multiple locations, albeit with a posterior predominance. Multifocal spike foci are now considered a characteristic finding in Panayiotopoulos syndrome. These sometimes take the form of cloned-like, repetitive, mulifocal spike wave complexes in which repetitive spike or sharp and slow wave complexes appear concurrently in different brain locations of one or both hemispheres. The EEG abnormalities in Panayiotopoulos syndrome are accentuated in sleep. Figure 23-4 illustrates the variability of the interictal EEG in Panayiotopoulos syndrome.

Rarer EEG findings in Panayiotopoulos syndrome include small, sometimes inconspicuous, spikes, slow waves intermixed with small spikes and brief generalized discharges. Focal or diffuse slowing may be seen post-ictally. Occasionally, repeated EEGs can all be normal. Although fixation-off sensitivity is common, photosen-sitivity is exceptional.

The frequency, location, and persistence of spikes do not determine the clinical manifestations, severity, and frequency of seizures or the prognosis of Panayiotopoulos syndrome (53, 54).

A number of ictal EEGs in Panayiotopoulos syndrome have been reported showing focal discharges of rhythmic theta or delta, often with spikes. Onset is usually posterior (61, 66, 68-70), but may be anterior as shown in Figure 23-2 (61, 71).

In MEG combined with MRI, equivalent current dipoles cluster preferentially in cortical locations along the parietal-occipital, the calcarine, or the central fissure. The equivalent current dipole clustering may be unilateral or bilateral, monofocal or multifo-cal (33, 72, 73). These findings are in keeping with

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