Hemiconvulsion-hemiplegia-epilepsy syndrome

C P Panayiotopoulos MD PhD (Dr. Panayiotopoulos of St. Thomas' Hospital has no relevant financial relationships to disclose.)
Jerome Engel Jr MD PhD, editor. (Dr. Engel of the David Geffen School of Medicine at the University of California, Los Angeles, has no relevant financial relationships to disclose.)
Originally released October 29, 1999; last updated June 28, 2019; expires June 28, 2022

This article includes discussion of hemiconvulsion-hemiplegia-epilepsy syndrome, HHE, HHES, and febrile status epilepticus. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.


Hemiconvulsion-hemiplegia syndrome is an exceptional dramatic sequence of a sudden and prolonged unilateral clonic seizure (hemiconvulsion) followed by permanent ipsilateral hemiplegia. In 80% of patients, the syndrome is completed with the development of severe epileptic seizures, hemiconvulsion-hemiplegia-epilepsy syndrome, after 1 to 3 years from the initial episode. Peak age of occurrence is in the first 2 years of life, with a range of 5 months to 4 years. The event occurs suddenly in an otherwise normal child, often during a febrile illness of CNS infection. The initial flaccid hemiplegia later becomes spastic; it is permanent and often very severe. Learning difficulties is probably the rule. Acute and immediate treatment of the hemiconvulsion status epilepticus is mandatory.

Key points


• Hemiconvulsion-hemiplegia-epilepsy syndrome is a disorder associated with a specific clinical presentation sequence: initial prolonged hemiconvulsion (at less than 2 years of age) and immediate flaccid hemiplegia (a hemiconvulsion-hemiplegia episode), and subsequent (after 1 to 3 years) development of focal epilepsy.


• The focal partial epilepsy may be temporal, extratemporal, or multifocal.


• Onset is associated with the presence of prolonged seizures often in a febrile context. Early administration of a benzodiazepine to reduce the duration of the initial event is of primary importance.


• Although the syndrome may be associated with prior infection or lesion in some cases, a possible cause is often not revealed.


• Therapy for hemiconvulsion-hemiplegia-epilepsy syndrome includes antiepileptic drugs and surgery.

Historical note and terminology

The term "hemiconvulsion-hemiplegia syndrome" was first used by Gastaut (Gastaut et al 1957; Gastaut et al 1960) to describe the following sequential combination: unilateral or predominantly unilateral clonic seizures (usually of long duration), occurring during the first 2 years of life and immediately followed by a flaccid hemiplegia (usually permanent), ipsilateral to the clonic seizure.

The term "hemiconvulsion-hemiplegia-epilepsy syndrome" was used to describe the complete form of the syndrome. It included the consequent development of a focal epilepsy, usually occurring after 1 year to several years following the initial hemiconvulsion-hemiplegia episode. Focal seizures were considered to be mainly of temporal lobe origin.

In their more comprehensive study, Gastaut and associates considered previous publications of this condition, and on the basis of 150 cases, they described hemiconvulsion-hemiplegia-epilepsy syndrome as follows (Gastaut et al 1960):


Some infants present, in the course of an acute febrile illness, one or many convulsions, sometimes an epileptic status, followed by an ipsilateral motor deficit. They show, upon recovery from the acute stage, a flaccid paralysis which is gradually replaced by a spastic condition and, months or years later, a chronic epilepsy, which is rarely of the sensory or motor type, but usually of the psychomotor type. This combination of initial hemiconvulsions and hemiplegia, free interval with possible regression of the motor deficit, and ultimate appearance of psychomotor epilepsy forms a clinical entity which has been known for some time but its clinical, electroencephalographical, radiological and pathological features have only recently been studied by the Marseille School, which proposed to call it: hemiconvulsion-hemiplegia-epilepsy.

Further studies (Roger et al 1972; Roger et al 1982; Chauvel et al 1991; Chauvel and Dravet 2002) have demonstrated that the initial episode may be observed in various situations and that the subsequent partial epilepsy can be temporal, extratemporal, or multifocal.

It can be argued that, taken separately, both the initial episode (hemiconvulsion-hemiplegia) and the subsequent development of epilepsy are not proper "syndromes." In fact, the hemiconvulsion-hemiplegia episode corresponds to a unique episode of focal status epilepticus responsible for a unilateral motor deficit, and the later development of epilepsy corresponds to a structural focal epilepsy. However, the stereotyped sequence of events that characterizes hemiconvulsion-hemiplegia epilepsy allows some authors to consider it as a syndrome (Arzimanoglou 2010). Thus, hemiconvulsion-hemiplegia-epilepsy was reintroduced as a syndrome by the ILAE Task Force on Classification and Terminology (Engel 2001). In the published ILAE revised terminology and concepts report, hemiconvulsion-hemiplegia-epilepsy syndrome is considered a "clinically distinctive constellation" (Berg et al 2010). However, in the current relevant ILAE position papers for classification and terminology, the term “clinically distinctive constellation” has been abandoned, and hemiconvulsion-hemiplegia-epilepsy syndrome is not cited (Fisher et al 2017; Scheffer et al 2017).

According to an expert consensus definition, infantile hemiconvulsion-hemiplegia and epilepsy syndrome is a specific syndrome in a patient less than 2 years old, presenting as new-onset refractory status epilepticus with unilateral motor seizures, high-grade fever at the time of onset of refractory status epilepticus, and unilaterally abnormal acute imaging, followed by hemiparesis lasting at least 24 hours, and excluding definite infectious encephalitis (Hirsch et al 2018).

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