Gyratory epilepsy in a patient with a thalamic neoplasm

In humans, striato-pallido-thalamic projections are largely segregated by their origin in either the striosome-like or matrix-like compartments

Cortico-striato-thalamo-cortical (CSTC) loops are fundamental organizing units in mammalian brains. CSTCs process limbic, associative, and sensorimotor information in largely separated but interacting networks. CTSC loops pass through paired striatal compartments, striosome (aka patch) and matrix, segregated pools of medium spiny projection neurons with distinct embryologic origins, cortical/subcortical structural connectivity, susceptibility to injury, and roles in behaviors and diseases. Similarly, striatal dopamine modulates activity in striosome and matrix in opposite directions. Routing CSTCs through one compartment may be an anatomical basis for regulating discrete functions. We used differential structural connectivity, identified through probabilistic diffusion tractography, to distinguish the striatal compartments (striosome-like and matrix-like voxels) in living humans. We then mapped compartment-specific projections and quantified structural connectivity between each striatal compartment, the globus pallidus interna (GPi), and 20 thalamic nuclei in 221 healthy adults. We found that striosome-originating and matrix-originating streamlines were segregated within the GPi: striosome-like connectivity was significantly more rostral, ventral, and medial. Striato-pallido-thalamic streamline bundles that were seeded from striosome-like and matrix-like voxels transited spatially distinct portions of the white matter. Matrix-like streamlines were 5.7-fold more likely to reach the GPi, replicating animal tract-tracing studies. Striosome-like connectivity dominated in six thalamic nuclei (anteroventral, central lateral, laterodorsal, lateral posterior, mediodorsal-medial, and medial geniculate). Matrix-like connectivity dominated in seven thalamic nuclei (centromedian, parafascicular, pulvinar-anterior, pulvinar-lateral, ventral lateral-anterior, ventral lateral-posterior, ventral posterolateral). Though we mapped all thalamic nuclei independently, functionally-related nuclei were matched for compartment-level bias. We validated these results with prior thalamostriate tract tracing studies in non-human primates and other species; where reliable data was available, all agreed with our measures of structural connectivity. Matrix-like connectivity was lateralized (left > right hemisphere) in 18 thalamic nuclei, independent of handedness, diffusion protocol, sex, or whether the nucleus was striosome-dominated or matrix-dominated. Compartment-specific biases in striato-pallido-thalamic structural connectivity suggest that routing CSTC loops through striosome-like or matrix-like voxels is a fundamental mechanism for organizing and regulating brain networks. Our MRI-based assessments of striato-thalamic connectivity in humans match and extend the results of prior tract tracing studies in animals. Compartment-level characterization may improve localization of human neuropathologies and improve neurosurgical targeting in the GPi and thalamus.

Gyratory seizures as a presentation of temporal encephalocele

Gyratory seizures (GS) are rare and have been reported in focal (frontal and temporal) as well as generalized epilepsies. The exact neuroanatomical substrate of gyration during a seizure is not clearly understood, but is thought to be due to the involvement of the basal ganglia. The direction of gyration occurring without head version is thought to have ipsilateral cerebral origins, while gyrational seizures preceded by forced head version are suggestive of seizure onset contralateral to the direction of gyration or the presence or absence of forced head version is thought to have important implications for lateralization of seizure origins from the direction of gyration. This case describes gyratory seizures in a young boy with a temporal encephalocele. Report of MRI brain initially indicated no abnormalities, but careful review revealed a left temporal encephalocele. PET scan showed left temporal hypometabolism. The patient underwent a left anterior temporal resection with amygdalohippocampectomy (ATL + AH) and is seizure-free for 18 months. Temporal encephalocele is the most commonly iatrogenic but may also be spontaneous, post-traumatic, or in relation to chronic otitis media. This case suggests that gyratory seizures may be a unique presentation of temporal encephalocele and this possibility warrants investigation in patients with medically refractory epilepsy.

Localization value of ictal turning prone

PURPOSE

Ictal semiology complements ictal EEG in identifying the likely epileptogenic zone. Ictal turning prone (ITP) with body turning of 90 ° or more can be seen with frontal lobe epilepsies. The aim of our study was to evaluate the localizing value of ITP in a general population of patients undergoing long term video-EEG monitoring.

METHODS

We reviewed our epilepsy monitoring unit database for adult patients with recorded habitual seizures with ITP. All 16 patients identified had continuous video-EEG monitoring using standard scalp electrodes; eight patients also had intracranial EEG monitoring. We only included focal seizures without evolution to bilateral tonic-clonic activity.

RESULTS

We identified 16 patients with ITP, mean age of 32.5 years (range 18-50). ITP was consistently seen in at least one focal impaired awareness seizure of all patients. Ictal onset zone on scalp EEG was left temporal in five, right temporal in three, left frontal convexity in two, right frontal convexity in two, probable right medial frontal in three and probable left medial frontal in one patient. Direction of ITP was uni-directional in 12 patients while 4 patients had ITP in opposite direction in different seizures. Nine patients underwent epilepsy surgery; five patients had Engel class I outcome and four patients had Engel class III outcome.

CONCLUSIONS

Ictal turning prone does not have a consistent single localizing or lateralizing value and can be seen with various epileptogenic zones including medial frontal, lateral frontal or temporal. ITP direction can vary even with a single epileptogenic zone.

Ictal body turning in focal epilepsy

Despite the explanations of many lateralization findings, body turning in focal epilepsy has been rarely investigated. One of the aims of this study was to evaluate the role of ictal body turning in the lateralization of focal epilepsies. The records of 263 patients with focal epilepsy (temporal lobe epilepsy (TLE), n=178; extratemporal lobe epilepsy (ETLE), n=85) who underwent prolonged video-EEG monitoring during presurgical epilepsy evaluation were reviewed. Preoperative findings (TLE, n=16; ETLE, n=6) and postoperative outcomes (TLE, n=7) of patients with focal epilepsy with ictal body turning were assessed. For the evaluation of ictal body turning, two definitions were proposed. Nonversive body turning (NVBT) was used to denote at least a 90° nonforced (without tonic or clonic component) rotation of the upper (shoulder) and lower (hip) parts of the body around the body axis for a minimum of 3s. Versive body turning (VBT) was used to denote at least a 90° forced (with tonic or clonic component) rotation of the upper (shoulder) and lower (hip) parts of the body around the body axis for a minimum of 3s. Nonversive body turning was observed in 6% (n=11) of patients with TLE and 2% (n=2) of patients with ETLE. For VBT, these ratios were 5% (n=8) and 7% (n=6) for patients with TLE and ETLE, respectively. Nonversive body turning was frequently oriented to the same side as the epileptogenic zone (EZ) in TLE and ETLE seizures (76% and 80%, respectively). If the amount of NVBT was greater than 180°, then it was 80% to the same side in TLE seizures. Versive body turning was observed in 86% of the TLE seizures, and 55% of the ETLE seizures were found to be contralateral to the EZ. When present with head turning, NVBT ipsilateral to the EZ and VBT contralateral to the EZ were more valuable for lateralization. In TLE seizures, a significant correlation was found between the head turning and body turning onsets and durations. Our study demonstrated that ictal body turning is a rarely observed but reliable lateralization finding in TLE and ETLE seizures, which also probably has the same pathophysiological mechanism as head turning in TLE seizures.

Unilateral thalamic lesions and generalized or lateralized spike wave discharges

We report four adult patients who had thalamic lesions and lateralized or generalized spike wave discharges (SWDs). The first two patients also had cortical lesions. The role of the cortex and thalamus in the generation of SWDs is discussed. The third patient had a history of idiopathic generalized epilepsy (IGE) with intractable seizures. The last patient had partial seizures and absences. The coexistence of IGE with refractory focal epilepsy and the relation with thalamic lesions are discussed.

Test–retest stability of an experimental measure of human turning behaviour in right-handers, mixed-handers, and left-handers

Animals turn away from the hemisphere with the more active dopamine (DA) system. For humans, a similar relationship has been assumed, albeit that side preferences obtained from different measures are inconsistent. Given the important role of DA on human behaviour and cognition, a stable human turning measure is of significant experimental value. We assessed the stability (test and retest 4 weeks apart) of veering behaviour (lateral deviations during blindfolded straight ahead walking) in 20 healthy right-handers, 20 mixed-handers, and 20 left-handers. Veering behaviour did not differ between groups, and did not reveal any particular side preference in any group. Relationships of side preferences between testing sessions for the different handedness groups was low for right-handers, and showed some minor consistency for the mixed-handed group. Neither handedness nor footedness was significantly related to preferred veering side. These findings, if not related meaningfully to DA-mediated conditions (e.g., clinical populations, pharmacological studies, personality) in the future, suggests that veering behaviour is an inappropriate alternative to the animal turning model. These findings challenge the reliability of human turning measures, and invite more broadly for a critical evaluation of turning measures as an indicator of hemispheric DA asymmetries in human populations.

A case of 'circling seizures' and an intratumoral abscess

We describe a case of a 38-year-old woman who presented with 'circling' seizures and was found to have an intracranial mass with features consistent with a meningioma. Three weeks prior to her presentation she underwent an uncomplicated vaginal hysterectomy. However, after discharge to home she developed a 4-day history of fever, chills and night sweats that eventually resolved. She underwent surgical removal of her intracranial mass without difficulty but intra-operative pathology showed features of acute cerebritis at the margins of the tumor. Further sectioning of the mass revealed evidence of an intratumoral abscess. Culture of the meningioma revealed heavy growth of Bacteroides fragilis. The patient was treated with intravenous antibiotics, discharged home in excellent health and has had no recurrence of seizures. In our case report we will review the historical literature on the incidence and features of intratumoral abscess. Although it is considered a rare event, our case demonstrates both common and unique features about this occurrence and highlights an unusual chain of events in the natural history of the patient's meningioma and the way in which it became clinically apparent.

Spontaneous paroxysmal circling behavior in the ci2 rat mutant: epilepsy with rotational seizures or hyperkinetic movement disorder?

Circling, turning, rotating, spinning, wheeling, and cursive hyperkinesia are all synonymous terms used to describe the active movement of an animal in a circular direction. Circling behavior can be evoked by unilateral electrical and chemical stimulation or lesions of various brain sites, but can also occur after systemic drug administration or spontaneously in normal animals or mutant rodents. In humans, stereotypic body rotation can occur as a distinctive entity of generalized and focal epilepsy, and may be due to involvement of the striatum. We have previously described a Lewis rat mutant (ci2) with a behavioral phenotype characterized by lateralized circling, hyperactivity, opisthotonus, and ataxia. In these rats, circling occurs in phases or bursts either spontaneously or in response to stress. Neurochemical data indicate that the circling behavior of the ci2 mutants is related to an abnormal asymmetry in dopaminergic activity in the striatum. Because of the similarities to rotational epilepsy, we used video and electroencephalographic recordings to study whether the rotational behavior of the ci2 mutant rat is a result of a partial or generalized epilepsy. Epileptic WAG/Rij rats were used for comparison. Video monitoring of ci2 rats in the absence of any stress or disturbance showed that circling occurs in paroxysmal bursts during active wakefulness, but not during passive wakefulness or sleep. Circling was not preceded or followed by any convulsive motor seizures and was not associated with epileptiform abnormalities in the electroencephalogram, whereas WAG/Rij rats exhibited myoclonic seizures and epileptic spike-wave discharges during passive wakefulness and sleep. As a result of the association of circling with active wakefulness, ci2 rats exhibited many more rotations during the dark (active) phase compared with the light (rest) period. Increase in active wakefulness during the light phase by transfer of the rats to a new environment induced or intensified circling behavior. Most ci2 rats showed a consistent lateral preference during circling, but some rats changed their preference from one session to another. The data indicate that spontaneous paroxysmal circling behavior in the ci2 rat is not a consequence of epilepsy but reflects a hyperkinetic movement disorder with abnormal lateralization of brain function.

Circling seizures in a case with Wilson's disease

We report a case of Wilson's disease with circling seizures. Because of the existence of other types of frontal automatism and the EEG focus on the frontal regions, circling seizures of the patient were thought to originate from the frontal lobe. Magnetic resonance imaging demonstrated large cavitary lesions on bilateral frontal lobes. The mechanisms of circling behavior are discussed in association with Wilson's disease.

Rotatory seizures in juvenile myoclonic epilepsy

Rotatory seizures have been reported in association with focal intracranial lesions. This type of seizure was also described in patients with primary generalized epilepsies. To our knowledge, there is only one previous publication denoted an association between juvenile myoclonic epilepsy (JME) and rotatory seizures. We present two female patients with JME and rotatory seizures together. The onset of myoclonic jerks and generalized tonic clonic (GTC) seizures was in their midteens. Their interictal EEGs showed bilateral symmetric spike and polyspike wave discharges. The rotatory seizures of the patients started at age of 26 and 33 years, respectively. In one of the patients, turning to the left was followed by three or four complete turns, after then, she had GTC seizures. The other patient has turned to the right with only one or two turns and sometimes continued with GTC seizures. Neuroradiologic investigations including brain CT, MRI, and SPECT were performed. Response to valproate therapy of rotatory seizures was good. We believe that rotatory seizures are rarely seen in JME patients, and this causes false diagnosis which lead unsuitable drug choice.

Circling seizures

Twelve cases with circling seizures are presented with their clinical, electroencephalographic and radiological findings. Four patients had symptomatic partial epilepsy, five had cryptogenic partial epilepsy, and the remaining three had idiopathic generalized epilepsy. Three of the patients with symptomatic partial epilepsy had frontal lesion, and one had parito-occipital lesion. Turning direction had no lateralizing value in patients with partial epilepsy. Based on our study we conclude that circling seizures may occur in different epileptic syndromes and epilepsies. In cases with symptomatic partial epilepsy, lesions are mostly located in frontal lobes but also in parietooccipital areas.

Circling seizures in a case of juvenile myoclonic epilepsy

Circling seizures (CS) have been described in association with focal lesions as well as with generalized EEG discharges. We report 1 patient with juvenile myoclonic epilepsy (JME) who developed CS. There were no focal findings on clinical examination, EEG, or imaging studies. We propose that CS in this patient may represent a profound asymmetry in expression of an idiopathic generalized epilepsy rather than a partial condition.