The patient is an 11-year-old ambidextrous female with symptomatic intractable epilepsy who was referred for evaluation and treatment . At three years of age, she developed a fever, became confused, and within 2-3 hours began having persistent right hemibody myoclonic/clonic activity She was admitted to an intensive care unit, and multiple antiepileptic drugs were required to fully control her seizures . Cerebrospinal fluid studies were positive for herpes simplex virus (HSV) . Her initial EEG showed bilateral, independent, temporal, periodic epileptiform discharges (see Figure 17. 1), and her initial neuroimaging studies revealed bilateral temporal edema Though she was aggressively treated with acyclovir, the encephalitis caused significant impairment in (primarily short-term) memory, receptive and expressive language function (less than 15 words spoken intelligibly), and intractable epilepsy However, she remembers individuals' names and several events prior to her neurological insult Her present seizure semiology consists of predominantly generalized myoclonic and tonic events, with a frequency of 10-25 seizures per week Prior medications include topiramate, phenobarbital, val-proic acid (which caused hyperalbuminemia), oxcarbazepine, and phenytoin A vagus nerve stimulator (VNS) was placed at the age of 9 years, but this was also unsuccessful in controlling her seizures Her present antiepileptic medications include lamotrigine, felbamate, and zonisamide A recent video-EEG study revealed interictal generalized and independent left and right
temporal epileptiform discharges (see Figure 17.2A) . Two of ten seizures witnessed during monitoring were focal in onset, and these rapidly secondarily generalized. She also had generalized myoclonic/tonic events (see Figure 17. 2B) that resembled flexor spasms (with elevation and flexion of both upper and lower extremities), and generalized myoclonic-astatic events during which she would fall forward . A brain MRI study revealed left temporal lobe encephalomalacia, as well as periventricular and subcortical white-matter signal hyperintensities; there was also widening of the sylvian fissure, and deepening and widening of sulci extending into the posterior portion of the left temporal lobe (see Figure 17. 3) . Neuropsychological testing revealed a functional level comparable to a 2- to 3-year-old child, and significant short-term memory deficits After reviewing the results, a complete corpus callosotomy was recommended . At the 6-month follow-up visit, her mother described five brief (<1 minute) seizures, three of which involved right hemibody and two with left arm and face involvement . She has not had any generalized events nor has she fallen or injured herself since surgery.
Viral encephalitis is one of the most common causes of symptomatic status epi-lepticus . HSV, affecting about 1 or 2 cases per 500,000 per year, is the most common cause of encephalitis in the United States . HSV acquired congenitally or in the
FiGuRE 17.2 (A) Inter-ictal discharges (bipolar, anterior-posterior montage): (1) Right hemispheric discharge, maximal negativity in the temporal parietal region (initial dashed circles); (2) Left posterior temporal inter-ictal discharge (solid circle); (3) Generalized discharge followed by attenuation with no clinical correlate (B) Myoclonic/tonic seizure (bipolar, anterior-posterior montage) Generalized polyspike and wave followed by low-amplitude faster-frequency activity with overriding myogenic artifact This is interrupted by episodic right posterior quadrant discharges . Clinically, the patient had a generalized myoclonic jerk followed by tonic stiffening
FIGuRE 17.3 Axial FLAIR images depicting left temporal lobe encephalomalacia, and periventricular and subcortical white-matter signal hyperintensity primarily involving the left hemisphere . There was also widening of the sylvian fissure, and deepening and widening of sulci extending into the posterior portion of the left temporal lobe An increase in the signal of the right medial temporal structures was also seen
FIGuRE 17.3 Axial FLAIR images depicting left temporal lobe encephalomalacia, and periventricular and subcortical white-matter signal hyperintensity primarily involving the left hemisphere . There was also widening of the sylvian fissure, and deepening and widening of sulci extending into the posterior portion of the left temporal lobe An increase in the signal of the right medial temporal structures was also seen neonatal period (often HSV type 2) is a diffuse process with a different clinical presentation and course than that acquired during childhood (often HSV type 1) Though childhood-acquired HSV may have a wide spectrum of clinical presentations, it has a predilection for the limbic system and the temporal lobes The case discussed represents a child who acquired herpes simplex encephalitis (HSE) at 3 years, which caused symptomatic intractable epilepsy and significant neurocogni-tive/neurodevelopmental deficits
Fever and confusion should immediately alert the physician to the possibility of central nervous system (CNS) involvement Partial seizures, though sometimes seen in other causes of encephalitis, are often a presenting symptom in herpes encephalitis In a patient presenting with a seizure, meningitis, and other infectious processes, focal malignant or benign lesions, or a fever or illness that may have lowered the seizure threshold, have to be ruled out Other symptoms suggestive of HSV include headache (irritability in younger children), unusual behavior, lethargy, vomiting, and other neurological symptoms such as cranial nerve findings and localized deficits Symptoms are more nonspecific in very young children who may present with decreased activity or irritability and inconsolable crying
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