Gelastic seizures and fever originating from a parietal cortical dysplasia.

Gelastic seizures (GS) is an uncommon seizure type characterized by sudden inappropriate attacks of uncontrolled and unmotivated laugh and its diagnostic criteria were elaborated by Gascon. These criteria included stereotypical recurrence of laugh, which is unjustified by the context, associated signs compatible with seizure, and ictal or interictal abnormalities. GS can be cryptogenic or symptomatic of a variety of cerebral lesions, the most common being hypothalamic hamartoma. However, GS associated with other types of cerebral lesions are exceedingly rare. The physiopathologic mechanisms of this type of seizure are still undefined. Two reports have described a non-lesional GS arising from a parietal focus. In this paper, we report the first case of lesional GS associated to the parietal area of the brain in a child and this case has associated fever that is likely an ictal symptom.

Introduction

Gelastic seizures (GS) are an uncommon seizure type; they are characterized by sudden inappropriate attacks of uncontrolled and unmotivated laugh. They were first described by Trousseau.[1] One century later, the term gelastic epilepsy (from gelos: Joy), was suggested by Daly and Mulder to define epileptic fits where laughter is the only or predominant symptom.[2] The diagnosis criteria were given by Gascon; these included stereotypical recurrence of laugh, which is unjustified by the context, associated signs compatible with seizure, and ictal or interictal abnormalities. GS could be cryptogenic or symptomatic of a variety of cerebral lesions, most commonly hypothalamic hamartoma.[3]

However, GS associated with other types of cerebral lesions are exceedingly rare. The physiopathologic mechanisms of this type of seizure are still undefined. Two reports have described a non-lesional GS arising from a parietal focus. In this paper we report the first case of GS lesion associated to the parietal area of the brain in a child. This case also has associated fever that is likely an ictal symptom.

Case Report

A 5-year-old boy was referred to our department for recurrent fever and uncontrolled epilepsy. The patient was the youngest one in a family of five children born out of a consanguineous marriage, but without any other significant familial history. He was born at full-term without any perinatal problem, and weighed 3,400g.

The neuro-psychomotor development of the patient was globally normal. He walked at the age of 13 months and acquired verbal language at the age of 18 months and his first seizures occurred by the age of 14 months. These attacks were characterized by generalized tonic clonic seizures with a frequency of 1–2 times per month. He was initially treated using phenobarbital then Valproate without any significant improvement. By his 4th year, the patient started expressing daily laughing attacks that were occurring 2–3 times a day while each was lasting for about a minute. This stereotypical laugh was unrelated to the context; the patient was generally unconscious during attacks and experienced post-ictal amnesia. Most often, an undescribed feeling occurred prior to seizure associated with left hemi-corporeal paresthesia. These seizures were associated to episodes of fever up to 39.5°C; these episodes occurred almost everyday and resolved spontaneously in less than 3 h. The fever rose with the start of gelastic attack and lasted 2–3 hours and sometimes occurred independently.

The physical and neurological evaluation of the patient was essentially normal. He was 104 cm tall (50th percentiles), weighting 17 kg (50th percentiles) with 50th percentiles head circumference.

Complete paraclinical investigations were performed, this included C-reactive protein, sedimentation rate, leukocyte count, urinalysis, lumbar puncture, thorax radiography, cardiac and abdominal ultrasound - and were not suggestive of infection.

A cerebral magnetic resonance imaging (MRI) revealed a lesion in the right parietal area, suggestive of cortical dysplasia. Functional MRI was performed using sensory tasks which showed activation in the sensory cortical area as well as in the lesion [Figure 1]. Interictal Electroencephalography (EEG) showed sporadic active spiking in the right temporal region [Figure 2]. Valproate was reintroduced without any improvement. Carbamazepine and later Clobazam were added but did not prevent seizures. Lamotrigine and vigabatrin were proposed before suggesting surgical treatment.

Figure 1

Fluid attenuation inversion recovery magnetic resonance image showing a hyperintense lesion in the right parietal area

Figure 2

Interictal scalp electroencephalography indicating repetitive spikes in the parietal area

Discussion

GS represent less than 1% of all epilepsies.[4] They are mostly associated to hypothalamic hamartoma, drug resistance, precocious puberty, and mental decline.[5-9]

Secondary GS outside diencephalic lesion are very rare; they are most often attributed to a temporal focus.[1011] Rarely, they might originate from an extra temporal area. A frontal origin was usually reported,[12-14] while parietal localization is exceptional. Among these localizations, the right hemisphere appears to be most frequently involved.[7]

Some differences in clinical profiles were noticed in reports of the literature according to the localization of the epileptic activity.[15]

Whenever GS arise from a hypothalamic hamartoma, laughter is usually unmotivated. It can appear sometimes natural and forced;[11] and the seizure is not accompanied by a rupture of contact. The clinical presentation varies largely in the case of temporal focus. The laughter may be natural or forced, unmotivated or in response to a pleasant sensation. A rupture of contact is observed in 50% of cases.[15]

The laughter is unnatural in frontal focus; and appears as if being forced, non-communicative without any affective connotation; and rupture of contact is frequently observed.[12-14]

A single patient was reported with parietal localization of the epilepsy, he was presenting veritable laughter attacks, described as inappropriate, involuntary and with contact rupture.

An ictal smile arising from the parietal lobe was observed in two other patients.[716] Our case is probably the third one with parietal localization, and the only among the three, which is related to a cortical dysplasia.

The physiopathologic mechanisms of this type of seizure are unclear and still need elucidation. Various anatomical regions have been reported to elicit laughing; this includes, hypothalamus, anterior cingulate gyrus, the orbito-frontal cortex, the baso-lateral temporal cortex, supplementary motor area and possibly parietal area.[16] Several studies using electrical stimulation and ictal SPECT have demonstrated that joy feeling is dependent on the basal temporal cortex while motor aspect of laughter is organized in anterior cingulate area.[17-20] In hypothalamic hamartoma, seizure is directly generated in hypothalamus and paroxysmal activity is spread in temporal area through hypothalamic-amygdala connections.[21]

Schematically, all anatomical areas mentioned above are organized in a large neuronal network, and activating one of these areas may activate a part or the whole network leading to GS.[10]

Fever has been rarely described in the literature as ictal or peri-ictal symptom and has never been associated to GS.[22] Few cases of peri-ictal fever were reported, mainly related to non-convulsive seizure and rarely with a confusion state.[22-25]

The physiopathology of fever is not yet clear. Several hypotheses have been discussed, three of them being important. First, the hypothalamus might be involved in the pathogenesis, ictal activity could spread to the hypothalamus via neuronal connections and would involve the pre-optic area including localized thermoregulation center leading to central thermoregulation disturbance during few hours.[22] However, fever has never been reported in hypothalamic hamartoma, with the fact that ictal activity spreads from hamartoma towards the cortex, while the other way is not true.[26]

Regarding our patient, the ictal activity seems to be generated in the cortical area; both fever and GS probably resulted from hypothalamic involvement, which supports the major role of hypothalamus in the neuronal network described above.

The two other hypotheses consist of pyrogenes production during the ictal activity[27] and vagal nerve nuclei involvement that was demonstrated using vagal nerve stimulation treatment. Indeed, the role of the vagal nerve in temperature elevation is correlated to increased blood perfusion of the hypothalamus in-patients treated with vagal nerve stimulation.[28]

Fever might accompany the GS when it originates from cortical focus in temporal, frontal or parietal cortical areas; this could be misdiagnosed or most often underreported as a peri-ictal symptom since infection is usually thought of in such a patient.

Fever should be investigated in epileptic patients in order to better assess the prevalence of this feature as a peri-ictal symptom. In the mean time, it is interesting to review all reported literature for better understanding the pathophysiological mechanisms involved in both GS and peri-ictal fever.