Originally described by Marinus Rulandus in 1597,2 benign rolandic epilepsy (BRE) is classified as an idiopathic, localization-related epileptic syndrome. It is characterized by:
- nocturnal generalized seizures of probable focal onset
- diurnal partial seizures arising from the lower rolandic area
- an EEG pattern consisting of a midtemporal-central spike focus3-16
Both daytime and nighttime seizures may occur, although in most children the seizures usually occur during sleep. More than half of the children with BRE have nocturnal seizures only.14 Approximately 15% have seizures during sleep and while awake, and 10% to 20% have them in the waking state alone.17 The increase in seizure incidence during sleep parallels the increase in spikes seen during drowsiness and sleep on the EEG.
The disorder always begins during childhood. The age range is from 3 to 13 years, with the peak incidence occurring between the 7th and 8th year of life.14 It is somewhat more common in boys than in girls.4,5,17,18 Most affected children have normal intelligence and normal findings on the neurologic examination.18
The disorder is usually familial. Fifty percent of close relatives (siblings, children, and parents of the probands) demonstrate the EEG abnormality between the ages of 5 and 15 years. Before 5 and after 15 years of age, penetrance is low, and few patients demonstrate the abnormality. Only 12% of patients who inherit the EEG abnormality have clinical seizures. The EEG trait of midtemporal central spikes has been linked to chromosome 15q15, but the epilepsy appears to have a multifactorial inheritance.19
Diagnosis of the syndrome, which depends on the patient's history and EEG features, allows the clinician to offer the patient and parents a rational plan for treatment, genetic counseling, and prognosis.
The syndrome is called rolandic epilepsy because of the characteristic feature of partial seizures involving the region around the lower portion of the Rolandic fissure. The same syndrome is sometimes called benign childhood epilepsy with centrotemporal spikes (BCECTS).
Features of seizures
Lombroso20 described the characteristic features of seizures in BRE:
- somatosensory stimulation of the oral-buccal cavity
- speech arrest
- preservation of consciousness
- excessive pooling of saliva
- tonic or tonic-clonic activity of the face
Less often, the somatosensory sensation will spread to the face or arm. Rarely, a typical jacksonian march of tonic or tonic-clonic activity will occur.
Although the somatosensory aura is quite common, a history of this symptom is frequently not elicited, especially in young patients.20
Motor phenomena during daytime attacks are usually restricted to one side of the body and include tonic, clonic, or tonic-clonic events. These attacks most frequently involve the face, although the arm and leg may be involved. Although seizures rarely generalize when the patient is awake, the sensory or motor phenomena may change sides during the course of the attack.16 Arrest of speech may occur at the beginning of the seizure or during its course. Consciousness is rarely impaired during daytime attacks.
After the seizure the child may feel numbness, pins and needles, or "electricity" in the tongue, gums, and cheek on one side. Postictal confusion and amnesia are unusual in benign rolandic epilepsy.
In nocturnal seizures the initial event is typically clonic movements of the mouth, along with salivation and gurgling sounds from the throat. Secondary generalization of the nocturnal seizure is common. The initial focal component of the seizure may be quite brief, so parents may not see this portion of the seizure. Some nocturnal seizures remain partial and do not generalize. It is likely that the frequency of seizures during sleep is underreported.
Seizure frequency in benign rolandic epilepsy is typically low. 4,17,18 Lerman17 states that 10% to 13% of children will have only one seizure, regardless of drug therapy. In a study of 100 patients with benign rolandic epilepsy, Lerman and Kivity18 found that 13 of the patients had only one seizure and 66 had infrequent seizures. However, 21% of the patients had frequent seizures. Status epilepticus is extremely rare in this disorder.
Patients with clearly typical clinical and EEG features do not need a CT or MRI.
BRE is characterized by a very distinctive EEG pattern. The characteristic interictal EEG abnormality is a high-amplitude, usually diphasic spike with a prominent following slow wave (See EEG). The spikes (<70 milliseconds) or sharp waves (<200 milliseconds) appear singly or in groups at the midtemporal (T3, T4) and central (rolandic) region (C3, C4). When bipolar recording montages are used, the spikes may appear most prominent in the central or midtemporal region and usually occur synchronously in both regions. Although typically present in both regions, at times they may shift from one to the other or be seen only in the midtemporal or central region.
The rolandic discharges typically occur only during childhood, peaking at about age 10.
The spikes may be confined to one hemisphere or occur bilaterally. The spike focus is unilateral in about 60% of patients. In 40% there are bilateral spike foci either on the initial EEG or on subsequent recordings.17 Unilateral spikes do not have a predominance for either hemisphere in patients with this syndrome. When bilateral, the spikes can be synchronous or asynchronous, symmetric or asymmetric.
Rolandic spikes usually occur on a normal background. However, when the spikes occur frequently, focal slowing may appear to occur in the region of the spikes. This "pseudoslowing" is secondary to the slow waves accompanying the spikes.
The spikes are often activated by sleep.21,22 In approximately 30% of children with BRE, spikes appear only in sleep.21 Sleep states are usually normal in BRE. Some records show generalized spike-wave discharges without any concomitant clinical signs of absence seizures.22 These diffuse spike-and-wave discharges, which can occasionally occur during the awake state, are strongly activated by sleep.22 Most children with BRE who have spike-wave discharges during sleep do not have typical absence seizures.
Adapted from: Holmes GL. Classification of seizures and the epilepsies. In: Schachter SC, Schomer DL, eds. The comprehensive evaluation and treatment of epilepsy. San Diego, CA: Academic Press; 1997. p. 1-36.
With permission from Elsevier (www.elsevier.com)