Magnetoencephalographic analysis in children with Panayiotopoulos syndrome

Signal change in hippocampus and current source of spikes in Panayiotopoulos syndrome

A 4-year-old girl with Panayiotopoulos syndrome presented with a history of 4 prolonged autonomic seizures. The clinical features of her seizures included, in order of occurrence, blank staring, pallor, vomiting, hemi-clonic movement on the right side, and unresponsiveness. A brain magnetic resonance imaging (MRI) showed a slightly high T₂ signal in the left hippocampus. Interictal electoencephalogram revealed spikes in the occipital area of the left hemisphere. We analyzed the current-source distribution of the spikes to examine the relationship between the current source and the high T₂ signal. The current source of the occipital spikes was not only distributed in the occipital area of both cerebral hemispheres, but also extended to the posterior temporal area of the left hemisphere. These findings suggest that the left temporal lobe may be one of the hyperexcitable areas and form part of the epileptogenic area in this patient. We hypothesized that the high T₂ signal in the left hippocampus of our patient may not have been an incidental lesion, but instead may be related to the underlying electroclinical diagnosis of Panayiotopoulos syndrome, and particularly seizure. This notion is important because an abnormal T₂ signal in the hippocampus may represent an acute stage of hippocampal injury, although there is no previous report of hippocampal pathology in Panayiotopoulos syndrome. Therefore, long-term observation and serial follow-up MRIs may be needed to confirm the clinical significance of the T₂ signal change in the hippocampus of this patient.

Brain maturation-related spike localization in Panayiotopoulos syndrome: magnetoencephalographic study

Focal spike activities in Panayiotopoulos syndrome involve all brain regions in electroencephalography, and commonly reveal multiple foci, often through occipital predominance. To investigate correlations between developmental brain maturation and spike origin in Panayiotopoulos syndrome, we evaluated age-related or duration-related magnetoencephalographic spike localization in 25 patients with Panayiotopoulos syndrome. Regarding age at examination, patients with frontal spikes were significantly older than patients with spikes on rolandic, parieto-occipital, or calcarine sulci. Occipital spikes were classified into two subgroups, located at the calcarine sulcus and parieto-occipital sulcus. Both calcarine and parieto-occipital localizations were seen in patients around the same age. Follow-up magnetoencephalography was performed on three patients, and demonstrated shifting localization or disappearance of magnetoencephalographic spikes. These results suggest that the location of spike discharges is not directly related to seizure symptoms, but instead indicates maturation-related cortical hyperexcitability in patients with Panayiotopoulos syndrome.

Panayiotopoulos syndrome: a benign childhood autonomic epilepsy frequently imitating encephalitis, syncope, migraine, sleep disorder, or gastroenteritis

BACKGROUND

Panayiotopoulos syndrome is a common idiopathic childhood-specific seizure disorder formally recognized by the International League Against Epilepsy. An expert consensus has defined Panayiotopoulos syndrome as "a benign age-related focal seizure disorder occurring in early and mid-childhood. It is characterized by seizures, often prolonged, with predominantly autonomic symptoms, and by an EEG [electroencephalogram] that shows shifting and/or multiple foci, often with occipital predominance."

OBJECTIVE

The purpose of this review is to provide guidance for appropriate diagnosis and management of Panayiotopoulos syndrome.

CLINICAL FEATURES

Autonomic epileptic seizures and autonomic status epilepticus are the cardinal manifestations of Panayiotopoulos syndrome. Autonomic seizures in Panayiotopoulos syndrome consist of episodes of disturbed autonomic function with emesis as the predominant symptom. Other autonomic manifestations include pallor (or, less often, flushing or cyanosis), mydriasis (or, less often, miosis), cardiorespiratory and thermoregulatory alterations, incontinence of urine and/or feces, hypersalivation, and modifications of intestinal motility. In approximately one fifth of the seizures the child becomes unresponsive and flaccid (ictal syncope) before or often without convulsions. Cardiorespiratory arrest is exceptional. More-conventional seizure symptoms often appear after the onset of autonomic manifestations. The child, who was initially fully conscious, becomes confused and unresponsive. Eyes turn to one side or gaze widely open. Only half of the seizures end with brief hemiconvulsions or generalized convulsions. Convulsive status epilepticus is extremely rare. Autonomic symptoms may be the only features of the seizures. Half of the seizures in Panayiotopoulos syndrome last for >30 minutes, thus constituting autonomic status epilepticus, which is the more common nonconvulsive status epilepticus in normal children. Two thirds of seizures occur during sleep.

EPIDEMIOLOGY

Panayiotopoulos syndrome probably affects 13% of children aged 3 to 6 years who have had 1 or more afebrile seizures and 6% of such children in the 1- to 15-year age group.

DIAGNOSTIC TESTS

An electroencephalogram is the only investigation with abnormal results, usually showing multiple spikes in various brain locations.

PATHOPHYSIOLOGY

Panayiotopoulos syndrome is probably the early-onset and Rolandic epilepsy the late-onset phenotype of a maturation-related benign childhood seizure-susceptibility syndrome. Ictal epileptic discharges in Panayiotopoulos syndrome, irrespective of their location at onset, activate autonomic disturbances and emesis, to which children are particularly vulnerable. The symptoms/sequence of autonomic seizures and autonomic status epilepticus in Panayiotopoulos syndrome are specific to childhood, and they do not occur in adults.

PROGNOSIS

Panayiotopoulos syndrome is remarkably benign in terms of seizure frequency and evolution. Autonomic status epilepticus imparts no residual neurologic deficit. The risk of epilepsy in adult life seems to be no higher than in the general population. However, autonomic seizures are potentially life-threatening in the rare context of cardiorespiratory arrest, an area in which additional study is required. MISDIAGNOSIS: The clinical features of Panayiotopoulos syndrome are frequently mistaken as nonepileptic conditions such as acute encephalitis, syncope, migraine, cyclic vomiting syndrome, motion sickness, sleep disorder, or gastroenteritis. The consequence is avoidable misdiagnosis, high morbidity, and costly mismanagement.

MANAGEMENT

Education about Panayiotopoulos syndrome is the cornerstone of management. Prophylactic treatment with antiepileptic medication may not be needed for most patients. Autonomic status epilepticus in the acute stage needs thorough evaluation; aggressive treatment may cause iatrogenic complications including cardiorespiratory arrest.