Midline Spikes in Children and Clinical Correlations

To the Editor: Kutluay et al. (1) highlighted midline spikes and associated seizure semiology, a subject that has previously received little attention, as reviewed elsewhere (2). Midline spikes alone were found in 35 (0.2%) of 20,000 EEGs. These commonly occurred in children and were significantly associated with heterogeneous types of focal and generalized seizures of idiopathic (16 cases), symptomatic (13), or undetermined cause (6). Onset of seizures was mainly between ages 1 and 6 years (21 of 35 cases) (1). Midline spikes were facilitated by sleep or occasionally seen only during sleep (1). We supplement these observations with our results from an ongoing prospective study from 1998 (3,4). At the end of the first 3 years, we had recorded 424 EEGs in 308 children aged 1–14 years; 228 (74%) had one or more epileptic seizures. All EEGs were recorded digitally, which allows optimal study of midline and other spike locations; in old paper EEGs, midline spikes are not detected in montages that do not include midline electrodes. Of 228 patients with seizures, 21 (9.2%) had at least one EEG with midline spikes alone (six, or 2.6%) or together with spikes in other, usually multiple, locations (15, or 6.6%). Midline spikes were frequently of high amplitude and in clusters but could also be small, singular, and sparse (Fig. 1). For comparison, occipital spikes alone or with other, including midline, spikes were found in 36 (16%) cases. Centrotemporal spikes alone or with other, including midline, spikes were found in 48 (21%) cases. Top: EEGs of a child with Panayiotopoulos syndrome. At age 9 years, he had pure autonomic status epilepticus that lasted for 4 h. He felt tired, complained of headache, became agitated, and was very pale. Within 5 min, he started banging his head on the wall and soon became unresponsive and floppy "like a rag doll." He was doubly incontinent, his eyes were widely open, and pupils were markedly dilated. At this stage, he vomited vigorously. Recovery without convulsions started 4 h from onset. He did not convulse at any stage. One day a year later, he had two left-sided rolandic seizures of unilateral facial twitching, each lasting 5–10 min. The first EEG had only midline spikes at Cz electrode, occasionally forming an ill-defined dipole with F4 positivity. The second EEG had centrotemporal spikes forming a dipole with midline positivity. There were no midline spikes. Occasionally a positive occipital spike also was recorded. The third EEG had infrequent and scattered small spikes mainly at O2 and C3 electrodes. Bottom: Interictal EEGs of three children with typical seizures of Panayiotopoulos syndrome. Left: Repetitive multifocal spike–wave complexes with midline spikes. Middle: Independent multifocal spikes at various locations including midline spikes. Right: First EEG had predominantly midline spikes alone or synchronous with other spikes, but the second EEG 4 months later had multifocal spikes in other than midline locations. Five of the six patients with at least one EEG having midline spikes only had normal development. These had febrile seizures (one case), rolandic epilepsy (one), Panayiotopoulos syndrome (one), occipital and a single complex partial seizure (one), and brief seizures with loss of consciousness only (one). The only symptomatic case had generalised convulsions. In follow-up EEGs of these 6 children, none of them had only midline spikes alone (fig). Instead, midline spikes occurred together with centrotemporal, occipital or other spikes in various combinations (3 patients), disappeared but spikes were seen in other locations (1) or EEGs were normalised (2). Significantly, of the 21 patients with midline spikes alone or in combination with other spikes, six had definite Panayiotopoulos syndrome (another four were possible cases of the same syndrome) manifesting with single or infrequent autonomic seizures, autonomic status epilepticus, or both (4,5). Conversely, midline spikes were present in 15% of patients with this syndrome (4). Our results are generally in agreement with those of Kutluay et al. (1), but it appears that midline spikes (a) are much more frequent than previously appreciated (which is attributed to improved detection with digital EEGs); (b) usually occur together with spikes in other locations; more rarely, they occur alone, but this is not a consistent localisation in serial EEGs of the same patient; and (c) are significantly associated with benign childhood focal seizures and particularly with Panayiotopoulos syndrome. From a practical point of view, an EEG with midline and multifocal spikes in a normal child with a single or a few seizures should raise the possibility of benign childhood seizures and particularly of Panayiotopoulos syndrome of autonomic seizures and autonomic status epilepticus (2,4,5).

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