4. Electroencephalographic findings and neuroimaging

### 4.1 EEG and video-EEG monitoring

Diffuse slowing of the main background activity is typical that is revealed in the first EEG recordings. At first epileptic cause of these EEG phenomena may remain

### Malignant Migrating Partial Seizures of Infancy (Coppola-Dulac Syndrome) DOI: http://dx.doi.org/10.5772/intechopen.82838

undetected, especially if symptoms include only short autonomic paroxysms. Epileptiform disorders in disease onset are rare. However, in 3 of 14 patients in the observation by Gerard et al. [4], originally normal background EEG was observed; later, slowing with variable asymmetry was recorded in all cases. Often, slow-wave accentuation in one of the EEG recordings is more pronounced in one hemisphere, while the later study may reveal dominating slow-wave lateralization from the opposite side. Multiregional spikes without clear activation during sleep are registered in all cases during development of the disease. However, pathognomonic interictal EEG pattern in MMPSI is absent. During the period relatively free of seizures, stage differentiation in the structure of sleep EEG may persist, but sleep spindles are rare and usually asymmetric [3]. When seizures become very frequent, interictal activity is almost absent.

Ictal EEG patterns involve different areas of the cerebral cortex in the course of successive seizures. Ictal pattern is a rhythmic activity of alpha and theta range, occurring in one region with adjacent regions involvement during seizure, followed by a gradual decrease of the frequency characteristics. Caraballo with colleagues, analyzing 17 infants with MMPSI, had distinguished three different EEG patterns: 8 cases with alternating simple focal motor seizures at onset, and the ictal EEG pattern was characterized by recurrence of rhythmic focal spikes or rhythmic sharp theta or alpha activity in the Rolandic region; 5 cases with complex focal seizures and progressive appearance of polymorphic theta-delta in temporo-occipital regions recurring independently; and 4 cases with focal complex seizures with motor manifestations and ictal EEG with flattening or fast activity in frontotemporal region followed by unilateral fast polyspikes in alternating clusters in both hemispheres. Correlations between these three patterns with severity or prognosis were not found [27]. Electro-clinical seizure patterns last from 1 to 4 minutes. Multiple subclinical ictal EEG patterns lasting from 30 seconds to 1 minute are also typical [1]. Observations show an alternative cortical section of both hemispheres' involvement in epileptogenesis, which implies the presence of a diffuse pathological process in the cerebral cortex [3].

When seizures become very frequent, initial zone of ictal pattern shift from one region to another and from one hemisphere to another occurs. As a result, extended, migratory ictal activity, which forms a complex EEG pattern of status epilepticus, develops [1–3].

Video-EEG monitoring plays the most important role in the MMPSI diagnosis, as it is able to detect a correlation between ictal pattern localization of and clinical characteristics of seizure. Thus, ictal pattern in the frontal region produces clinical signs in the form of tonic tension or clonic spasms in the contralateral limb; ipsilateral automatisms or a versive seizure with alternating tonic phenomena and fencing posture are possible. EEG pattern is localized in perirolandic area and manifests with contralateral clonus of the lips, tongue, facial muscles, and hypersalivation. Temporal EEG patterns clinically manifest with broad "frozen" gaze ("staring" phenomenon) and oro-alimentary automatisms. Ictal EEG patterns originating from occipital cortex correlate with lateralized clonic eyes and head twitching. In the case of parietal pattern, nonspecific motor activity is possible; sometimes, a child seems "listening" to his/her inner feelings. The above phenomena are contrary to a prevailing opinion that there is no clear clinical-electroencephalographic correlation of focal ictal patterns in infants and rather suggest the opposite.

As child grows, the amplitude of ictal activity tends to increase with growing involvement of the frontal lobes; many seizures become secondarily generalized. The phenomenon of secondary bilateral synchronization typically occurs after only a few weeks from the onset [1]. However, Gerard et al. [4] in the last observations found a delay of bilateral synchronization and additional foci of epileptiform

patients (42.8%), 13 patients (37.1%) had microcephaly, and optic nerve atrophy was observed in 27 patients (77.1%). Disorders of bulbar innervation were observed in all patients, while in nine children (25.7%), these impairments were bulbar syndrome, and in 26 children (74.3%) – pseudobulbar syndrome. All patients with

Seizure types Patients (n) % Tonic versive seizures 35 100 Tonic spasms 33 94.3 Ophthalmo-tonic seizures 35 100 Ophthalmo-clonic seizures 11 31.4 Atonic seizures 23 65.7 Dialeptic (pseudoabsences) 19 54.3 Pharyngo-oral seizures 18 51.4 Tongue clonus 7 20 Hemiclonic 19 54.3 Jacksonian march 11 31.4 Automotor 8 22.9 Apnea with cyanosis 14 40 Autonomic with vomiting 5 14.3 Focal myoclonic 18 51.4 Bilateral myoclonic 13 37.1 Fragmentary "erratic" myoclonus 5 14.3 GTCS 14 40 SE of migratory minor motor seizures 35 100 SE of inhibitory seizures 12 34.3 Hemiconvulsive SE 11 31.4 SE of tonic spasms 10 28.6 Myoclonic SE 9 25.7 SE of GTCS 8 22.9

Epilepsy - Advances in Diagnosis and Therapy

hypertonus, 16 children (45.7%) had diffuse muscle hypotonia, and 9 children had dystonic changes (25.7%). Severe movement disability with tetraparesis was formed in all of the children with MMPSI. Neurological disorders were expressed at birth (n = 16, 45.7%) or developed with the onset of seizures (n = 19, 54.3%) and tended to a steady progression in all the patients. All children with MMPSI had delay of motor and mental development (n = 35, 100%), up to a complete development stop

Diffuse slowing of the main background activity is typical that is revealed in the first EEG recordings. At first epileptic cause of these EEG phenomena may remain

MMPSI had changes in the muscle tone: 10 children (28.6%) had spastic

Epileptic seizure types in patients with malignant migrating partial seizures of infancy (n=35)

4. Electroencephalographic findings and neuroimaging

in 26 infants (74.3%).

116

Table 2.

4.1 EEG and video-EEG monitoring

activity generation, at least up to 2 months from the onset (possibly as antiepileptic drug effect) [4]. At this stage detection of early drug resistance may result to a wrong decision about surgical treatment. Extended video-EEG monitoring also has a considerable importance in this category of patients, because visualization of seizures originating from the same cortex area does not mean that all seizures originate only from this area [28].

Despite the various topographies, ictal EEG patterns of all episodes are very similar and correspond to rhythmic activity of the alpha or theta range, prone to the spread and involving all large cortex areas [7].

EEG in personal patients (n = 35) was characterized by diffuse slowing of background activity, while in the developed stage, background EEG was almost completely replaced by continuous ictal patterns. In the initial stages of the disease, interictal record revealed regional or multiregional epileptiform discharges with formation of multifocal independent spike foci (MISF) pattern. Most cases of MMPSI (20 patients, 57.1%) initially had MISF with transformation in MMPSI as frequency of epileptic seizures increased and migratory status developed. In seven cases (20%), monofocal epilepsy was initially observed, followed by addition of extra foci, new types of seizures, and increase of multifocal ictal events up to SE. At eight infants (22.9%), the first properly done EEG investigation fixed the multiregional SE pattern with its preservation in dynamic video-EEG studies and negative prognosis for live.

Ictal EEG patterns in the developed stage of MMPSI involved different areas of the cerebral cortex during a series of seizures, which could overlap each other in cases when ictal pattern in one area is not yet over, but the same pattern appeared in other cortical areas. There may be a complex picture, combining postictal changes in one region of the cerebral cortex, initial ictal pattern in another area, and developed ictal pattern in the third. Typical EEG pattern of MMPSI is presented in a series of electroencephalograms (Figures 1–7). In general, ictal pattern

### Figure 1.

Patient G.E., 1 year old. Diagnosis: Malignant migrating partial seizures of infancy. EEG during status seizures. Emergence of regional ictal EEG pattern in the left frontal region in the form of fast epileptiform activity and transformation to regular activity of theta range with amplitude increase and sharp wave inclusion. In the left parietal, posterior temporal region is seen delta-accentuation after the previous seizure. Manifestation: Rightsided tonic seizure with oro-facial and versive components.

demonstrates migration of paroxysmal ictal characteristics from one region to another, without formation of stable interregional relations. Probably, only due to ictal pattern migration, patients are able to stay in SE of focal seizures for a long

The same patient. Continuation of ictal EEG. Ictal epileptiform activity in the frontal areas changes to the rightsided lateralization. Manifestation: Transformation to asymmetric tonic seizure with left-sided accentuation.

The same patient. Continuation of ictal EEG. Ictal epileptiform activity involves neighboring regions and same areas of the right hemisphere, but with maintenance of left-sided lateralization. Manifestation: Bilateral tonic

Malignant Migrating Partial Seizures of Infancy (Coppola-Dulac Syndrome)

DOI: http://dx.doi.org/10.5772/intechopen.82838

time without development of life-threatening cerebral edema.

Figure 2.

seizure.

Figure 3.

119
