Long-term EEG monitoring for difficult seizure problems.

Long-term electroencephalographic (EEG) monitoring, initially popular in the form of 24-hour video-EEG telemetries developed for the evaluation of patients who were candidates for epilepsy surgery, is now possible in diverse configurations. Studies can be designed to evaluate a variety of diagnostic problems and can be individualized to address specific clinical questions for each patient. A great variety of severe epilepsies present in infancy and childhood with daily seizures, often presenting difficult diagnostic problems. Extending the benefits of long-term EEG monitoring to these patients early in the course of the epileptic process can be expected to result in more accurate diagnoses, more effective treatment, and improved prognoses. Long-term EEG monitoring is needed to improve our understanding of the nosology of infant epilepsy, which is incomplete.

Asymmetric hypsarrhythmia and infantile spasms in west syndrome.

The video encephalograms (EEGs) of 77 consecutive infantile spasms patients were evaluated for the presence of focal or asymmetric hypsarrhythmia and infantile spasms, to determine whether these findings were useful in predicting the presence of focal structural brain disease and were of any additional diagnostic or prognostic significance. Of the 77 patients with infantile spasms, 38% had focal or lateralized features present on video-EEG studies. Unilateral hypsarrhythmia and asymmetric ictal EEG changes during infantile spasms often occurred together: each always indicated the side of a focal or asymmetric structural cerebral lesion that was visible on computed tomographic or magnetic resonance imaging brain scan and was usually large. Clinically asymmetric infantile spasms were less common, always occurred in the presence of asymmetric ictal EEG changes, and did not appear to have additional localizing value. Lateralized hypsarrhythmia, with or without asymmetric infantile spasms, occurred in the presence of bilateral structural lesions that were more abnormal in the area of the greater EEG abnormality. Partial seizures also indicated symptomatic etiologies but were less localizing to visible focal lesions. Patients with symmetric hypsarrhythmia and infantile spasms rarely had focal/lateralized lesions visible on imaging studies. Although the majority of the symmetric group had structural brain disease, these brain lesions were diffuse, not lateralized. This group also included all patients who had cryptogenic etiology and normal development.

Clinical imitators of infantile spasms.

We report 53 infants who by clinical history were thought to have infantile spasms but who video-electroencephalograms showed were having other episodes that closely mimicked infantile spasms. Nine patients had other types of seizures. Forty-five patients had episodic symptoms that were not seizures: 11 patients had spasticity, four had gastroesophageal reflux, and the other patients had nonepileptic myoclonus, including 19 patients with benign neonatal sleep myoclonus. Three patients had more than one type of symptom. Infantile spasms imitators occurred in neurologically normal or abnormal infants, in patients with normal or abnormal interictal electroencephalograms, and in patients who also had previous or current infantile spasms. Differentiation of these episodes from infantile spasms prevented the initiation or continuation of anticonvulsant treatment appropriate for infantile spasms but inappropriate for these other behaviors.

The age-dependent epileptic encephalopathies.

The most severe epilepsies that affect neonates, infants, and children include Ohtahara, West, and Lennox-Gastaut syndromes. These three syndromes display considerable similarities and transitional features in their clinical symptoms, seizure phenomena, and electroencephalographic abnormalities. This review examines the similarities and differences between these three syndromes and the other severe epilepsies of infancy and childhood, and discusses the hypothesis that the three disorders form a continuum of epileptic encephalopathies that have a predictable age-related evolution.

Unusual variants of infantile spasms.

During evaluation of video-electroencephalograms (EEGs) performed in our laboratory, we identified 11 patients who had unusual repetitive movements that appeared to be variants of infantile spasms. Movements included yawning, facial grimacing, eye movements, and transient focal motor activity. These symptoms coincided with generalized attenuation, slow-wave transients, or other EEG ictal changes characteristic of infantile spasms. The background EEGs showed true or modified hypsarrhythmia. This series of patients shows that infantile spasms may be extremely subtle and clinically atypical. Patients who have these variants may or may not also have typical infantile spasms. In some patients, the seizures appear to be time-related or medication-induced modifications of more typical infantile spasms.

Seizures in series: similarities between seizures of the west and Lennox-Gastaut syndromes.

We observed seizures resembling infantile spasms in patients with Lennox-Gastaut syndrome (LGS). Infantile spasms, the type of seizures that occurs in patients who have West syndrome, have been well characterized by video-EEG studies and typically occur as a series of sudden generalized flexor or extensor jerks. The seizure types that occur in LGS have not been as clearly delineated. Some patients with West syndrome (WS) in early infancy later develop LGS. Using intensive video-EEG monitoring, we evaluated 14 LGS patients who had seizures that occurred in series. Clinically, the seizures greatly resembled infantile spasms, and the ictal EEG changes were identical to those that occur with infantile spasms. These findings expand the number of features known to be shared by these two syndromes and strengthen the hypothesis that the two syndromes represent age-related manifestations of similar epileptogenic processes.

Simultaneous infantile spasms and partial seizures.

We report 11 infants with infantile spasms who had partial seizures that occurred concurrently with the infantile spasms. We studied this phenomenon with time-locked video electroencephalography. The partial seizures began before the infantile spasms and continued after one or more infantile spasms in seven patients. An infantile spasm occurred at the beginning of the partial seizure in five patients. (One patient had both seizure types simultaneously.) The clinical descriptions of these combinations of seizures were confusing, since they did not match known seizure types. The genesis of these seizures may involve an interaction between processes of focal cortical epileptogenesis (partial seizures) and brain-stem synchronization (infantile spasms).

Episodic symptoms mistaken for seizures in the neurologically impaired child.

We found neurologically impaired children studied by time-locked video-EEG to have episodes of abnormal behaviors which had been mistaken for epileptic seizures. Recognition that other neurologically abnormal phenomena can closely mimic epilepsy is important for prevention of erroneous diagnoses of epilepsy, and thus overtreatment, in this patient population.

Seizures in relation to shunt dysfunction in children with meningomyelocele.

To determine whether seizures are a reliable sign of increased intraventricular pressure in children with shunt-dependent hydrocephalus and meningomyelocele, we performed a retrospective chart review of 346 patients with meningomyelocele and shunt-dependent hydrocephalus. Fifty-one patients had seizures. Seizure episodes were investigated to determine whether they were temporally associated with shunt dysfunction. Episodes of actual or presumed shunt dysfunction were analyzed as to presenting symptoms, ventriculogram, computed tomography scan, and shunt film results. These 51 patients had 129 admissions for possible shunt dysfunction. One hundred one admissions were due to increased intraventricular pressure; nine (9%) of these, had a seizure as one of the presenting symptoms. All of the nine episodes had other common presenting symptoms of shunt dysfunction, such as headache, vomiting, lethargy, or respiratory compromise. We conclude that seizures alone are an inadequate predictor of shunt dysfunction in children with meningomyelocele, but can be seen as one of the presenting symptoms.

Sleep, epilepsy, and the EEG in infancy and childhood.

Each of the major epileptic syndromes that occur in infants and children demonstrates relationships to sleep and wakefulness that are particular to that syndrome. These relationships include activation or suppression of clinical seizures during certain portions of the sleep-wake cycle, differences in symptomatology of the seizures or in seizure type, alterations in distribution or morphology of epileptiform waveforms, and changes in duration and composition of sleep stages. Knowledge of the interactions between sleep and seizures helps to increase understanding of the physiological mechanisms underlying epilepsy, as well as to improve clinical diagnosis.

Evaluation of macrocrania using computed tomography.

Computed tomographic scans were obtained on 72 consecutive infants and children who were referred because of a large head; 75% had hydrocephalus. Patients who had communicating hydrocephalus had the best prognosis. Prognosis of other types of hydrocephalus was poor, especially in cases showing cystic brain disease(porencephaly, multicystic disease, hydranencephaly). Nonhydrocephalic macrocranias were accounted for mainly by premature infants who had catch-up head growth and by patients who had primary megaloencephaly associated with abnormal neurologic development.

Septo-optic dysplasia in an infant of a diabetic mother.

Septo-optic dysplasia was found at autopsy in an infant of a diabetic mother. Optic nerve hypoplasia and holoprosencephaly have been reported in other patients. These findings suggest a propensity for maternal diabetes to affect development of the forebrain. Head circumference should be measured and funduscopic examination performed in all infants of diabetic mothers, and additional tests should be performed as indicated. Mental and motor retardation and hypothalamopituitary dysfunction may be found in these patients.

Exchange transfusion in neonatal myasthenia gravis.

An infant with transient neonatal myasthenia gravis had a double-blood-volume exchange transfusion because of maternal-fetal blood group incompatibility. This seemed to accelerate both decline in antiacetylcholine antibody titer and clinical improvement.

Changing response to caloric stimulation with gestational age in infants.

Internuclear ophthalmoplegia was found by caloric testing of the vestibuloocular reflex in normal, very premature infants, indicating that the medial longitudinal fasciculus is functionally immature. At this age, the medial longitudinal fasciculus is more responsive to stimulation by the oculocephalic (doll's-eye) reflex, which resulted in conjugate deviation of the eyes.

Acetazolamide-induced improvement in hydrocephalus.

The ability of acetazolamide to decrease ventricular size in a case of hydrocephalus was documented by computerized tomography.