Ictal single photon emission computed tomography in absence seizures: apparent implication of different neuronal mechanisms.

Absence seizures represent a complex group of epilepsy, characterized by lapse of consciousness with staring. Bilateral, synchronous, and symmetric bursts of 3-Hz spike-and-wave discharges are observed on the electroencephalogram, whereas interictal background activity is normal. This kind of epilepsy has to be differentiated from other generalized epilepsies such as juvenile absence epilepsy and juvenile myoclonic epilepsy. Moreover, absence seizures, together with generalized spike-and-wave discharges, may coexist with other types of epilepsy such as frontal lobe epilepsy, temporal lobe epilepsy, benign epilepsy with centrotemporal spikes, and childhood epilepsy with occipital paroxysms. We have carried out ictal single photon emission computed tomography (SPECT) in 10 patients with clinical evidence of absence seizures with the aim to better understand and to distinguish this kind of seizure as primarily or secondarily generalized to a specific area and to obtain more information on the neuronal mechanisms involved in the different types of seizures, usually not identifiable at the first appearance. During the long follow-up period (9 months to 14 years), 7 of the 10 examined patients underwent interictal SPECT when they became seizure free. Our data permitted, in two patients, the diagnosis of childhood absence seizures; in three patients, they suggested the possibility of later appearance of other seizure types, on the basis of focal hyperperfusion indicating a possible focal firing. In three of the examined patients, the diagnosis of idiopathic localization-related epilepsies mimicking childhood absence seizures could be performed. In the last two patients, the hypothesis of a coexistence of absences with partial and generalized seizures was considered. From our results, it can be presumed that ictal SPECT findings may contribute to the physiopathologic classification of the different types of epilepsies. Moreover, anticonvulsant treatment more appropriate to the different forms of seizures can be used.

Reflex inhibition of the quadriceps femoris muscle after injury or reconstruction of the anterior cruciate ligament.

A burst-superimposition technique was used to assess the strength of the quadriceps femoris muscle in three groups of patients. Group 1 comprised twenty patients who had had a torn anterior cruciate ligament of the knee and had a reconstruction of the ligament one to six months after the injury. Group 2 comprised twelve patients who had had a torn anterior cruciate ligament for an average of three months (a subacute tear). Group 3 comprised eight patients who had had a torn anterior cruciate ligament for an average of two years (a chronic tear). The patients in Groups 2 and 3 had not had an operation for the torn ligament. The patients in Groups 1 and 3 had no evidence of failure of activation of the involved quadriceps, but nine of the twelve patients in Group 2 had reflex inhibition of contraction of the muscle.