Recognition of psychogenic nonepileptic seizures diminishes acute care utilization.

Patients with psychogenic nonepileptic seizures (PNES) frequently use acute health care resources including emergency departments (EDs), resulting in redundant efforts. We asked whether establishing the diagnosis of PNES via video/EEG telemetry reduces subsequent ED use. Twenty-three patients with PNES were studied over a 48-month period surrounding the diagnosis using a provincewide database. There was a 39% reduction in total ED visits and a 51% reduction in ED visits for neurological causes during the 24 months following the diagnosis, and decreased ED use persisted throughout the follow-up period. There was no significant change in ED utilization for psychiatric causes. The proportion of patients with PNES who used ED services once or not at all per year increased from 26% in the 2 years prior to the diagnosis to 57% following the diagnosis. These findings suggest that a definitive, telemetry-based diagnosis relieves diagnostic uncertainties for the patient and physician, but also has quantifiable economic benefits.

White-matter diffusion abnormalities in temporal-lobe epilepsy with and without mesial temporal sclerosis.

BACKGROUND: Although epilepsy is considered a grey-matter disorder, changes in the underlying brain connectivity have important implications in seizure generation and propagation. Abnormalities in the temporal and extratemporal white matter of patients with temporal-lobe epilepsy (TLE) and mesial temporal sclerosis (MTS) have previously been identified. Patients with TLE but without MTS often show a different course of the disorder and worse surgical outcome than patients with MTS. The purpose of this study was to determine if said white-matter abnormalities are related to the presence of MTS or if they are also present in non-lesional TLE. METHODS: Seventeen patients with TLE and MTS (TLE+uMTS), 13 patients with non-lesional TLE (nl-TLE) and 25 controls were included in the study. Diffusion tensor imaging (DTI) was used to assess tract integrity of the fornix, cingulum, external capsules and the corpus callosum. RESULTS: The white-matter abnormalities seen in the fornix appear to be exclusive to patients with MTS. Although the cingulum showed an abnormally high overall diffusivity in both TLE groups, its anisotropy was decreased only in the TLE+uMTS group in a pattern similar to the fornix. The frontal and temporal components of the corpus callosum, as well as the external capsules, demonstrated reduced anisotropy in TLE regardless of MTS. CONCLUSIONS: While some white-matter bundles are affected equally in both forms of TLE, abnormalities of the bundles directly related to the mesial temporal structures (ie, the fornix and cingulum) appear to be unique to TLE+uMTS.

Exacerbation of pre-existing epilepsy by mild head injury: a five patient series.

OBJECTIVE: While the risk of developing seizures following a mild head injury has been reported and is thought to be low, the effect of mild head injury on patients with a pre-existing seizure disorder has not been reported. We present a series of cases where a strong temporal relationship between mild head injury and worsening of seizure frequency was observed. METHODS: Five cases were identified and reviewed in detail. Information was derived from clinic and hospital charts with attention to the degree of injury, pre- and postinjury seizure patterns and frequency. RESULTS: One patient has primary generalized epilepsy and four have localization related epilepsy. Prior to the head injury, three of the patients were seizure free (range: two to 24 years). The patients suffered from mild head injuries with no or transient loss of consciousness and no focal neurological deficits. In all cases, the patients experienced a worsening of seizure control within days of the injury. In one case, the patient's seizure pattern returned to baseline one year after the accident, while in the remaining four cases, the patients continue to have medically refractory seizures. CONCLUSIONS: A close temporal relationship between mild head injury and a worsening of seizure control was observed in five patients with epilepsy. Although further study is required, this observation suggests that a head injury that would be considered benign in the general population can have serious consequences such as recurrence of seizures and medical intractability in patients with epilepsy.

Marijuana use and epilepsy: prevalence in patients of a tertiary care epilepsy center.

The authors sought to determine the prevalence of marijuana use in patients with epilepsy by performing a telephone survey in a tertiary care epilepsy center. Twenty-one percent of subjects had used marijuana in the past year with the majority of active users reporting beneficial effects on seizures. Twenty-four percent of all subjects believed marijuana was an effective therapy for epilepsy. Despite limited evidence of efficacy, many patients with epilepsy believe marijuana is an effective therapy for epilepsy and are actively using it.

Localizing value of alpha-methyl-L-tryptophan PET in intractable epilepsy of neocortical origin.

BACKGROUND: [(11)C] alpha-methyl-L-tryptophan (alpha-MTrp) has been developed as a tracer for the study of the synthesis of serotonin in the brain with PET. However, it has been shown that in pathologic conditions the tracer may reflect the activation of kynurenine metabolism. Increased levels of serotonin and quinolinic acid have been described in resected epileptogenic cortex, raising the possibility that alpha-MTrp can localize seizure foci in patients with intractable partial epilepsy. The authors assessed the uptake of alpha-MTrp in 18 patients (11 men, mean +/- SD age 27.1 +/- 10.1 years, range 13 to 54) with intractable partial epilepsy to correlate the PET findings with the epileptogenic area defined by electroclinical and neuroimaging data. METHOD: Seven patients with cortical dysplasia (CD) and 11 with partial epilepsy in which conventional MRI and fluorine-18-deoxyglucose ((18)FDG)-PET studies failed to detect any abnormality were studied. All underwent scalp EEG monitoring during the PET scan to exclude ictal events and estimate the interictal epileptic activity. RESULTS: In seven patients (39%; CD four and cryptogenic partial epilepsy three), PET showed focal increased uptake of alpha-MTrp corresponding to the epileptogenic area. alpha-MTrp uptake in the epileptic focus correlated with the frequency of interictal spikes (r = 0.7, p < 0.05). CONCLUSIONS: alpha-MTrp-PET may be of value in the localization of the epileptogenic area not only in patients with visible dysplastic lesions, but also in those with cryptogenic partial epilepsy.

EEG telemetry with closely spaced electrodes in frontal lobe epilepsy.

The use of additional electrodes (other than standard 10-20 electrodes) has proved to be extremely useful in the investigation of patients with temporal lobe epilepsy. The development of 32- and 64-channel EEG machines, along with the reformatting capabilities of digital EEG has greatly increased the possibilities in the number of electrodes and recording montages. The authors wanted to determine whether the use of closely spaced electrodes designed to increase the coverage of frontocentral regions is of benefit in the investigation of patients with frontocentral epilepsy. Patients investigated for frontocentral epilepsy underwent EEG telemetry with closely spaced electrodes based on the 10-10 nomenclature. Twenty-three patients were studied. An additional 30 minutes was required by technicians to create the montage. Unilateral frontal or frontocentral epileptic abnormalities were observed in 10 patients, independent bifrontal in 5 patients, synchronous bifrontal in 4 patients, and no EEG changes in 4 patients. In no patient did the addition of closely spaced electrodes lead to a change in the classification of the EEG. Closely spaced electrodes did not reveal focal abnormalities, which were not already apparent with 10-20 electrodes, nor did they demonstrate evidence of laterality in bilaterally synchronous discharges.

Relationships between the epileptic focus and hand area in central epilepsy: combining dipole models and anatomical landmarks.

OBJECT: When considering resection of epileptic generators near the central sulcus, it is essential to define the spatial relationship between the epileptic generator and the primary sensorimotor hand area. In this study, the authors assessed the accuracy of dipole modeling of electroencephalographic spikes and median nerve somatosensory evoked potentials (SSEPs) in defining this relationship preoperatively and noninvasively. METHODS: Epileptic spikes and SSEPs in patients with focal central area epilepsy were represented by dipole models coregistered onto global magnetic resonance images. In patients who underwent surgery, spike dipoles were also compared with findings of electrocorticography (ECoG) and with the resection area. To improve the accuracy of the dipole models, anatomical landmarks of the hand area were used to assess the error in SSEP dipole location, and this error measure was used to correct the location of spike dipoles. Five patients with central epilepsy were studied, three of whom underwent ECoG-guided surgical resections. The location of SSEP dipoles correlated well with anatomical landmarks of the primary sensory hand area. The relative position of the spike and SSEP dipoles correlated well with the patients' ictal symptoms, ECoG findings, and the location of the epileptic focus (as defined by the resection cavity in patients who became seizure free postoperatively). Corrected spike dipoles were located even closer to the resection cavity. CONCLUSIONS: The calculation of the relative location of spike and SSEP dipoles is a simple noninvasive method of determining the relationship between the primary hand area and an epileptic focus in the central area. The spatial resolution of this technique can be further improved using easily identifiable anatomical landmarks.

The periodicity of lateralized epileptiform discharges.

OBJECTIVES: Although the term periodic lateralized epileptiform discharges (PLEDs) was introduced in 1964, there has been little discussion about the definition of periodicity, whether the degree of periodicity has clinical significance, and whether electroencephalographers can accurately assess periodicity. The objectives of this study were to determine if a mathematical descriptor of periodicity could analyse PLEDs and whether such has clinical relevance, to correlate the degree of periodicity with underlying etiology and to assess the accuracy of sight recognition of periodically occurring EEG events. METHODS: A 6 year retrospective analysis of EEGs on patients with PLEDs was undertaken. The coefficient of variation of inter-complex intervals was calculated for all records. The relative periodicity of each record was rated by electroencephalographers. Corresponding hospital records were reviewed with regard to clinical and pathological information. RESULTS: In cases of acute viral encephalitis, discharges were more periodic than in other etiologies (P = 0.013). Age, clinical state, and time of last seizure did not influence periodicity but 40 (70%) of 57 recordings with PLEDs were done within 2 days of a seizure. A history of seizures was present in 42 (89%) of 47 patients. Electroencephalographers' assessment of periodicity correlated well with measured periodicity (r = -0.49, P = 0.0001). However, EEGers were more likely to assess records as periodic if: discharges occurred frequently (r = -0.48, P = 0.0001), or the complexes were visually assessed to have a uniform morphology (r = 0.31, P = 0.02), even though neither of these factors influenced the periodicity of discharges. CONCLUSIONS: PLEDs were objectively measured to be more periodic when they were associated with acute viral encephalitis than with other etiologies. Nonetheless, the considerable overlap of values among the several presenting disorders diminished specificity. Electroencephalographers were able to recognize periodically occurring discharges. However, they were strongly influenced by discharge frequency and their perception of the uniformity of discharge morphology.

Intracranial EEG with very low frequency activity fails to demonstrate an advantage over conventional recordings.

PURPOSE: Conventional scalp and intracranial EEG is recorded within a limited band of frequencies (0.3-70 Hz) based on the premise that clinically relevant cerebral activity occurs within this frequency range. Ikeda et al. recently demonstrated focal very low frequency activity (VLFA), <0.3 Hz, at seizure onset for both intra- and extracranial recordings. The purpose of this investigation was prospectively to study VLFA during seizures in intracranial recordings to determine whether activity in this frequency range provides useful information regarding localization of seizure onset and spread. METHODS: Patients undergoing intracranial electrode implantation were studied by using a high-pass filter of 0.01 Hz. The timing, location, and pattern of seizure onset were first determined by using a digital high-pass filter of 0.3 Hz (conventional seizure onset). Seizures were then reviewed without digital filters and the presence of VLFA recorded, along with its timing and location. RESULTS: Forty-seven seizures were recorded in four patients. VLFA was not observed in 29 seizures and, in one other case, VLFA occurred simultaneous with movement. Of seizures with VLFA (n = 17), the timing and location of VLFA were not consistent with those of conventional seizure onset or propagation. CONCLUSIONS: Our study failed to demonstrate any clinical advantage of intracranial telemetry recordings with a high-pass filter of 0.01 Hz over conventional recordings with regard to determining the timing and location of seizure onset and propagation.

Periventricular leukomalacia and epilepsy: incidence and seizure pattern.

OBJECTIVE: To study the incidence and pattern of epilepsy in patients with periventricular leukomalacia (PVLM) in two specialty clinic settings. BACKGROUND: Motor and cognitive deficit as well as epilepsy are common in patients with PVLM. With modern imaging techniques, PVLM is now easily recognized. METHODS: Epileptic seizures and syndromes as well as motor and cognitive deficits were correlated with MRI findings. Two patient populations were studied: Group A-children with cerebral palsy and PVLM presenting to a center for children with motor disability (n = 19); and Group B-epileptic patients with PVLM presenting to a tertiary epilepsy center (n = 12). A single patient with PVLM and epilepsy who underwent extensive investigations, including intracranial EEG telemetry, is reported. RESULTS: In Group A, 47% of patients had epilepsy (9/19). PVLM was found in 1.27% of patients investigated for epilepsy at a tertiary epilepsy center (12/942). The majority of patients in both groups had multiple seizure types, with complex partial seizures being most common. Of patients with seizures (Groups A and B), 85.7% had intractable epilepsy (18/21). Intracranial EEG in the illustrative case demonstrated a multifocal epileptic process with occipitotemporal predominance. CONCLUSIONS: PVLM was an uncommon underlying cause in patients presenting with epilepsy (Group A); however, patients presenting with motor disability and PVLM (Group B) had a high incidence of seizures. PVLM in epileptic patients is associated with multiple seizure types and medically refractory disease.

Correlation of high-frequency oscillations with the sleep-wake cycle and cognitive activity in humans.

While several authors have suggested that high-frequency electroencephalogram activity (gamma, >30 Hz) correlates with conscious thought, others have suggested that electroencephalogram activity >30 Hz shows the same relationships to cognitive activity and sleep as activity in the conventional beta frequency band. The existence of coherence of gamma over large distances also remains controversial. We studied quantitatively the relationship of gamma activity to the sleep-wake cycle and cognitive tasks during wakefulness in humans using intracranial electroencephalogram. Gamma activity made up less than 1% of the total power spectrum. A significant relationship was observed between gamma activity and the sleep-wake cycle such that gamma was highest during wakefulness, intermediate during light and rapid eye movement sleep, and lowest during slow-wave sleep. As well, gamma was higher during rapid eye movement sleep with eye movements than during rapid eye movement sleep without eye movements. During a cognitive task experiment, while lower frequencies, including beta, showed a stepwise reduction with increasing task difficulty, gamma was observed to increase during cognitive tasks as compared to the resting state. The relationship between gamma and the sleep-wake cycle and cognitive tasks was independent of brain region and hemisphere. Coherence of gamma activity at distances of 5 mm and greater was not observed. Our data support previously reported findings that gamma activity has a significant relationship to the sleep-wake cycle. The findings of differences in gamma during REM sleep with and without eye movements suggest that the presence or absence of eye movements may reflect two different states of brain activity. Our findings of differences in the relationships of the beta and gamma bands to both the sleep-wake cycle and cognitive tasks demonstrate that various components of the high-frequency spectrum behave differently in some situations.

Distal hereditary upper limb muscular atrophy.

OBJECTIVES: To identify the clinical, electrophysiological, and genetic characteristics of a family with an unusual form of hereditary motor neuron disease. METHODS: Surviving members of a pedigree in which affected members presented with weakness and atrophy of distal musculature in the upper limbs were examined clinically and electrophysiologically, and had genetic testing. RESULTS: The disease was autosomal dominantly inherited and manifested as weakness and atrophy of distal musculature in the upper limbs, with minimal involvement of lower limbs, brisk reflexes, minimal sensory findings, and considerable variability in severity among the affected persons. Nerve conduction studies disclosed near normal motor conduction velocity, reduced motor compound action potential amplitude, prolonged distal motor latency, prolonged sensory latency, and normal sensory compound action potential amplitude. Needle electrode examination showed reduced number and increased size of motor unit potentials, but no fibrillations or fasciculations. CONCLUSION: Distal upper limb muscular atrophy is a distinct clinical entity.

Chronic periodic lateralized epileptiform discharges during sleep in a patient with caudate nucleus atrophy: insights into the anatomical circuitry of PLEDs.

OBJECTIVE: Periodic lateralized epileptiform discharges have been recognized for 33 years; however, little is known about the underlying mechanism causing periodic discharges. The following case provides an opportunity to study PLEDs in a patient with precisely localized subcortical grey matter lesions. METHODS: Routine EEGs and overnight polysomnography were performed on the study patient. Standard 10-20 electrode positions were used, as well as EOG and chin EMG for polysomnography. RESULTS: The study patient was a 39-year-old woman with severe left caudate nucleus atrophy and right hemi-dystonia. She had left ventral-lateral (VL) thalamotomies in 1989 and 1991, pallidotomy in 1992, and centromedian thalamic stimulator implantation in 1997. EEGs prior to surgical intervention demonstrated left hemisphere PLEDs during sleep. Following CM nucleus stimulatory implantation, the patient had overnight polsomnography. EEG during wakefulness and REM sleep was normal. With stages I-IV sleep left hemisphere PLEDs at 1-2 Hz were seen with fronto-temporal predominance. Sleep spindles were present bilaterally. There was no history of seizures, before or after surgery. CONCLUSIONS: The finding of PLEDs confined to synchronized sleep which were not affected by surgical manipulation of the motor basal ganglia circuit suggests a role of the associative basal ganglia circuit in the generation of periodic phenomenon.

Dihydroergotamine and metoclopramide in the treatment of organic headache.

Dihydroergotamine and metoclopramide have been used in the treatment of benign headache for many years. The presumed mechanism of action of dihydroergotamine and metoclopramide is related to these drugs' affinity for serotonergic receptors. We present three cases of the use of dihydroergotamine and metoclopramide in patients with organic headache (two patients with viral meningitis and one patient with meningeal carcinomatosis). All three patients had excellent symptomatic relief. Our results demonstrate that dihydroergotamine and metoclopramide can be effective in treating organic headache and, therefore, symptomatic relief can not be assumed to signify benign disease.

Limb-shaking transient ischemic attacks: Two case reports with unusual pathogenesis.

Limb-shaking transient ischemic attacks are associated with transient regional cerebral hypoperfusion and severe carotid stenosis. We report two patients with unusual pathogenesis of limb-shaking attacks, one a 73-year-old woman with right-sided limb-shaking attacks and normal carotid angiography (recently diagnosed with essential thrombocytosis, antiplatelet agents eliminated her attacks) and the other a 56-year-old woman with peptic ulcer disease and multiple episodes of left-sided limb-shaking. Severe anemia was found along with bilateral carotid stenoses >70%. Correction of her anemia abolished her limb-shaking episodes. The presumed pathogenesis of limb-shaking transient ischemic attacks is transient focal cerebral ischemia from severe occlusive disease. Our two patients demonstrate that the mechanisms of ischemia may include other factors that affect oxygen delivery such as anemia or platelet disorders.