Focal Clonic Seizures

Focal clonic seizures consist of the rhythmic jerking of unilateral muscle groups without impairment of consciousness. Clonic motor seizures originate in the primary


Mesial anatomy of the brain with correlation to certain seizure types.

motor cortex (Brodmann area 4) contralateral to the motor activity. The muscle groups that are involved strictly follow the cortical motor representation (homunculus, Figure 2.4). As face and hand have the biggest cortical representation, they are the most commonly involved muscle groups. If a seizure begins in the hand area, there may be spread of epileptiform activity rostrally and caudally. This translates clinically into a seizure that begins with clonic movements of the hand, with later involvement of the face and the leg as electrical spread occurs rostrally and caudally.

Focal clonic seizures are said to exhibit jacksonian march (2) if the seizure activity spreads clinically to follow the anatomical representation of the homunculus. When seizures continue for extended periods of time, without impairment of consciousness, this is referred to as epilepsia partialis continua. These motor seizures can last days, months, or even years.

Clonic motor seizures can occur with lesions in the primary motor cortex and can be refractory to antiepileptic medications. They are typical for benign epilepsy with centrotemporal spikes (benign Rolandic epilepsy) and Rasmussen's encephalitis. Benign child-

Rasmussen Encephalitis Epilepsy

Cortical motor representation. From Penfield W and Rasmussen T. 1955. The cerebral cortex of man.

Fencer Posturing Seizures

Typical postures of patients with SMA epilepsy. Left bilateral tonic arm extension. Right "fencing" posture.

hood epilepsy with centrotemporal spikes begins between 5 and 10 years of age (24). Patients have mainly nocturnal seizures with predominantly clonic movements of the face, throat constriction, and drooling. Occasional secondarily generalized tonic-clonic seizures occur. Seizures are often infrequent, and when treatment is indicated, responsive to carbamazepine. They remit spontanously in adolescence (24-26).

Rasmussen's encephalitis is a progressive, inflammatory, often unilateral disease of the brain, having unclear etiology (27). Autoimmune etiology has been assumed. It often manifests itself with prolonged focal clonic seizures, which may last for hours, days, or months (epilepsia partialis continua) and are contralateral to the affected hemisphere. Patients have completely preserved consciousness. With progression of the disease, atrophy of the affected hemisphere occurs and the patient becomes more cognitively impaired due to continuous seizure activity and progressive diffuse brain disease.

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  • duilio
    Can epilepsy limit a man's age?
    8 years ago
  • nicole
    Can a seizure be unilateral?
    7 years ago

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