Frontal lobe seizures

Medication-induced acute dystonic reaction: the challenge of diagnosing movement disorders in the intensive care unit

A 62-year-old man presented with left middle cerebral artery stroke. 1 h postadministration of tissue plasminogen activator, he received a total of 4 mg of haloperidol for combativeness. He developed partial complex status epilepticus, requiring benzodiazepines, phenytoin, propofol and intubation. 5 h later, he developed recurrent stereotyped tonic movements involving arching of the back, extension of the arms and contraction of opposing muscle groups. Repeat CT scan of the head showed evolving insular infarct. Differential diagnoses for these movements included tonic/clonic seizures, extensor (decerebrate) posturing from haemorrhagic conversion, neuroleptic malignant syndrome, or dystonic reaction. Given the lack of response to antiseizure medications, the recent administration of haloperidol, and the prompt resolution of movements following diphenhydramine administration, an acute dystonic reaction was considered. This atypical case of a critically ill patient with stroke highlights the fact that these patients may have multiple abnormal movements requiring careful analysis to guide diagnosis-specific management.

Looking for complexity in quantitative semiology of frontal and temporal lobe seizures using neuroethology and graph theory

Epileptic syndromes and seizures are the expression of complex brain systems. Because no analysis of complexity has been applied to epileptic seizure semiology, our goal was to apply neuroethology and graph analysis to the study of the complexity of behavioral manifestations of epileptic seizures in human frontal lobe epilepsy (FLE) and temporal lobe epilepsy (TLE). We analyzed the video recordings of 120 seizures of 18 patients with FLE and 28 seizures of 28 patients with TLE. All patients were seizure-free >1 year after surgery (Engel Class I). All patients' behavioral sequences were analyzed by means of a glossary containing all behaviors and analyzed for neuroethology (Ethomatic software). The same series were used for graph analysis (CYTOSCAPE). Behaviors, displayed as nodes, were connected by edges to other nodes according to their temporal sequence of appearance. Using neuroethology analysis, we confirmed data in the literature such as in FLE: brief/frequent seizures, complex motor behaviors, head and eye version, unilateral/bilateral tonic posturing, speech arrest, vocalization, and rapid postictal recovery and in the case of TLE: presence of epigastric aura, lateralized dystonias, impairment of consciousness/speech during ictal and postictal periods, and development of secondary generalization. Using graph analysis metrics of FLE and TLE confirmed data from flowcharts. However, because of the algorithms we used, they highlighted more powerfully the connectivity and complex associations among behaviors in a quite selective manner, depending on the origin of the seizures. The algorithms we used are commonly employed to track brain connectivity from EEG and MRI sources, which makes our study very promising for future studies of complexity in this field.

Neuroimaging characteristics of MRI-negative orbitofrontal epilepsy with focus on voxel-based morphometric MRI postprocessing

PURPOSE

The orbitofrontal (OF) region is one of the least explored regions of the cerebral cortex. There are few studies on patients with electrophysiologically and surgically confirmed OF epilepsy and a negative magnetic resonance imaging (MRI) study. We aimed to examine the neuroimaging characteristics of MRI-negative OF epilepsy with the focus on a voxel-based morphometric MRI postprocessing technique.

METHODS

We included six patients with OF epilepsy, who met the following criteria: surgical resection of the OF lobe with/without adjacent cortex, seizure-free for ≥12 months, invasive video-electroencephalography (EEG) monitoring showing ictal onset from the OF area, and preoperative MRI regarded as negative. Patients were investigated in terms of their image postprocessing and functional neuroimaging characteristics, electroclinical characteristics obtained from noninvasive and invasive evaluations, and surgical pathology. MRI postprocessing on T1 -weighted high-resolution scans was implemented with a morphometric analysis program (MAP) in MATLAB.

KEY FINDINGS

Single MAP+ abnormalities were found in four patients; three were in the OF region and one in the ipsilateral mesial frontal area. These abnormalities were included in the resection. One patient had bilateral MAP+ abnormalities in the OF region, with the ipsilateral one completely removed. The MAP+ foci were concordant with invasive electrophysiologic data in the majority of MAP+ patients (four of five). The localization value of 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) and ictal single-photon emission computed tomography (SPECT) is low in this cohort. Surgical pathology included focal cortical dysplasia, remote infarct, Rosenthal fiber formation and gliosis.

SIGNIFICANCE

Our study highlights the importance of MRI postprocessing in the process of presurgical evaluation of patients with suspected orbitofrontal epilepsy and "normal" MRI. Using MAP, we were able to positively identify subtle focal abnormalities in the majority of the patients. MAP results need to be interpreted in the context of their electroclinical findings and can provide valuable targets in the process of planning invasive evaluation.

Mice expressing the ADNFLE valine 287 leucine mutation of the Β2 nicotinic acetylcholine receptor subunit display increased sensitivity to acute nicotine administration and altered presynaptic nicotinic receptor function

Several mutations in α4 or β2 nicotinic receptor subunits are linked to autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). One such missense mutation in the gene encoding the β2 neuronal nicotinic acetylcholine receptor (nAChR) subunit (CHRNB2) is a valine-to-leucine substitution in the second transmembrane domain at position 287 (β2VL). Previous studies indicated that the β2VL mutation in mice alters circadian rhythm consistent with sleep alterations observed in ADNFLE patients (Xu et al., 2011). The current study investigates changes in nicotinic receptor function and expression that may explain the behavioral phenotype of β2VL mice. No differences in β2 mRNA expression were found between wild-type (WT) and heterozygous (HT) or homozygous mutant (MT) mice. However, antibody and ligand binding indicated that the mutation resulted in a reduction in receptor protein. Functional consequences of the β2VL mutation were assessed biochemically using crude synaptosomes. A gene-dose dependent increase in sensitivity to activation by acetylcholine and decrease in maximal nAChR-mediated [(3)H]-dopamine release and (86)Rb efflux were observed. Maximal nAChR-mediated [(3)H]-GABA release in the cortex was also decreased in the MT, but maximal [(3)H]-GABA release was retained in the hippocampus. Behaviorally both HT and MT mice demonstrated increased sensitivity to nicotine-induced hypolocomotion and hypothermia. Furthermore, WT mice display only a tonic-clonic seizure (EEG recordable) 3 min after injection of a high dose of nicotine, while MT mice also display a dystonic arousal complex (non-EEG recordable) event 30s after nicotine injection. Data indicate decreases in maximal response for certain measures are larger than expected given the decrease in receptor expression.

Thalamic T-type Ca²+ channels mediate frontal lobe dysfunctions caused by a hypoxia-like damage in the prefrontal cortex

Hypoxic damage to the prefrontal cortex (PFC) has been implicated in the frontal lobe dysfunction found in various neuropsychiatric disorders. The underlying subcortical mechanisms, however, have not been well explored. In this study, we induced a PFC-specific hypoxia-like damage by cobalt-wire implantation to demonstrate that the role of the mediodorsal thalamus (MD) is critical for the development of frontal lobe dysfunction, including frontal lobe-specific seizures and abnormal hyperactivity. Before the onset of these abnormalities, the cross talk between the MD and PFC nuclei at theta frequencies was enhanced. During the theta frequency interactions, burst spikes, known to depend on T-type Ca(2+) channels, were increased in MD neurons. In vivo knockout or knockdown of the T-type Ca(2+) channel gene (Ca(V)3.1) in the MD substantially reduced the theta frequency MD-PFC cross talk, frontal lobe-specific seizures, and locomotor hyperactivity in this model. These results suggest a two-step model of prefrontal dysfunction in which the response to a hypoxic lesion in the PFC results in abnormal thalamocortical feedback driven by thalamic T-type Ca(2+) channels, which, in turn, leads to the onset of neurological and behavioral abnormalities. This study provides valuable insights into preventing the development of neuropsychiatric disorders arising from irreversible PFC damage.

FDG-PET in the diagnosis of complex partial status epilepticus originating from the frontal lobe

Complex partial status epilepticus of frontal origin can manifest as nonconvulsive behavioral symptoms that mimic psychiatric illness and, thus, may elude timely diagnosis. The diagnosis can be further delayed by absence of ictal activity on scalp electroencephalography when the ictal origin is orbitofrontal or mesial frontal. We describe the case of a 51-year-old woman with clinically subtle complex partial status epilepticus of left orbitofrontal origin, lacking any clear ictal pattern on the electroencephalogram, who was finally diagnosed using positron emission tomography with [(18)F]fluorodeoxyglucose (FDG-PET). Subsequent FDG-PET following 5 days of oxcarbazepine therapy demonstrated resolution of the left orbitofrontal hypermetabolic focus. FDG-PET is a potentially useful modality for diagnosing nonconvulsive status epilepticus that is not evident on electroencephalography.

Frontal lobe epilepsy may present as myoclonic seizures

We describe a patient with seizures arising from right anterior-inferior frontal lobe presenting as myoclonic epilepsy. A 19-year-old man had experienced frequent paroxysmal bilateral myoclonic jerks involving his upper arms, shoulders, neck, and upper trunk since the age of 10. His baseline EEG showed intermittent right frontal spikes, and his ictal EEG showed rhythmic sharp theta discharges in the same area. MRI revealed cortical dysplasia in the right inferior frontal gyrus, and ictal-interictal SPECT analysis by SPM showed increased signal abnormality in this region. Diffusion tensor imaging (DTI) showed defects in fasciculi in the same area. These findings suggest that frontal lobe epilepsy should be considered in some patients with myoclonic seizures.

Behavioral manifestations of frontal lobe seizures

Patients with seizure of frontal lobe origin can present with bizarre behavior. At times, this bizarre behavior can be unrecognized or confused with seizure of other origin with nonepileptic events or with psychiatric disorder.

I recently saw a patient who began to experience events that were characterized by terrible fear which was followed by irritability. It was as if she could not stand in place where she was at and felt like running away. She was referred to a psychiatrist who diagnosed her to have panic disorder. She was subsequently treated for panic disorder. Her symptoms did not improve; therefore, she came to see me for a second opinion. Upon asking, the patient reported that the episodes were always the same and that they lasted approximately seconds to minutes. Due to the stereotypicity of the event and a normal routine electroencephalography (EEG), we requested that she would undergo a 24-hour video-monitoring EEG. Stereotypicity can help the physician in the differential diagnosis of psychiatric disorder versus a seizure disorder. During 24-hour video-monitoring EEG, she experienced several of these events. Also, a computer tomography scan was performed, which showed a small meningioma in the orbital frontal region.

Psychogenic nonepileptic seizures

PURPOSE OF REVIEW

This review summarizes the recent studies assessing patients with psychogenic nonepileptic seizures and developments in treatment.

RECENT FINDINGS

The misdiagnosis of nonepileptic seizure is costly to patients, the healthcare system, and to society. Patients with nonepileptic seizures are prescribed antiepileptic drugs that do not treat nonepileptic seizures, have multiple laboratory tests performed, and may not receive the necessary mental healthcare that could benefit them.The first step in nonepileptic seizure treatment is proper diagnosis. Video electroencephalography remains the gold standard for nonepileptic seizure diagnosis. Certain seizure types, such as frontal lobe seizures, may mimic nonepileptic seizure semiology. Bedside observations may augment video electroencephalography to establish nonepileptic seizure diagnosis. The methodology in nonepileptic seizure treatment trials is examined, describing the challenges in conducting clinical trials with patients with overlapping neurologic and psychiatric disorders. Finally, realizing that nonepileptic seizures are in a spectrum of somatoform disorders, diagnostic literature is reviewed in other conversion disorders.

SUMMARY

Nonepileptic seizure patients remain one of the most challenging populations to diagnose and treat in medical practice. Clinical findings and laboratory advances exist that more clearly establish the diagnosis of nonepileptic seizures. With the appropriate diagnosis, neurologists and mental health providers are better equipped to treat the underlying causes of nonepileptic seizures.

Psychosis as a manifestation of frontal lobe epilepsy

A 7-year-old girl presented with a cluster of seizures occurring in one day and followed by the development of paranoid delusions. Her electroencephalogram (EEG) revealed a psychomotor variant. Cranial MRI was normal, but the 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG) positron emission tomography (PET) scan showed hypometabolism in the left inferior frontal cortex. Her psychotic symptoms occurred episodically. Three years later, she developed hypermotor seizures associated with a fearful look. Video/EEG monitoring captured seizures of left frontotemporal onset. Her seizures became drug resistant and she underwent epilepsy surgery. Intracranial electrocorticography captured spontaneous and electrically induced seizures with onset in the left inferior frontal region, which was resected. She became seizure-free and her psychosis resolved. This case illustrates that frontal lobe epilepsy can present solely with psychotic symptoms, which may delay the diagnosis of epilepsy. We suggest that these cases may be underdiagnosed. When epilepsy is suspected and if MRI fails to demonstrate an abnormality, FDG PET scanning and video/EEG monitoring should be considered.