Structural brain lesions do not influence the prognosis of juvenile myoclonic epilepsy

In juvenile myoclonic epilepsy (JME) neuroimaging procedures are usually unnecessary but are often performed following the first generalized tonic-clonic seizure before a specific diagnosis has been reached. Our aim was to evaluate the influence of abnormal findings on the clinical presentation and prognosis of JME.

We retrospectively analyzed all medical records of JME patients first referred in two epilepsy centers (Marseilles, Nice) between 1981 and 1998.

Among 170 consecutive unselected newly diagnosed JME patients, neuroimaging was performed in 82 cases (MRI: 22, CT: 75, including MRI+CT: 15). In 4 subjects, specific neurological abnormalities had justified neuroimaging: severe head trauma after the onset of JME (2, both with lesions related to the trauma), multiple sclerosis with onset after JME (1, with normal MRI before the onset of multiple sclerosis and abnormal, specific findings later), severe mental retardation (1, with diffuse MRI changes but a typical electro-clinical presentation and evolution). In the other 78 cases, 9 had abnormal findings: common arachnoid cyst (3), mild diffuse cerebral atrophy and ventricular enlargement (1), mild ventricular enlargement only (3), septum lucidum cavum (1), mildly increased T2 signal in the left temporal lobe (1). Abnormal neuroimaging did not influence therapeutic decisions or prognosis.

These data confirm that neuroimaging procedures should not be routinely performed in patients with typical JME, unless additional neurological problems, that are unrelated to the diagnosis of epilepsy, occur.