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Parietal lobe epilepsy: the semiology, yield of diagnostic workup, and surgical outcome.

PURPOSE: To characterize the clinical features, the prognostic value, and diagnostic sensitivities of various presurgical evaluations and the surgical outcomes in parietal lobe epilepsy (PLE), we describe 40 patients who were diagnosed as having PLE, including 27 surgically treated patients. METHODS: The diagnosis was established by means of a standard presurgical evaluation, including magnetic resonance imaging (MRI), fluorodeoxyglucose-positron emission tomography (FDG-PET), ictal single-photon emission tomography (SPECT), and scalp video-electroencephalography (EEG) monitoring, with additional intracranial EEG monitoring in selected cases. RESULTS: Among the 40 patients, 27 experienced at least one type of aura. The most common auras were somatosensory (13 patients), followed by affective, vertiginous, and visual auras. The patients had diverse manifestations. Eighteen patients showed simple motor seizure, followed by automotor seizure, and dialeptic seizure. Two patients manifested generalized tonic-clonic seizures only, and 19 patients experienced more than one type of seizure. The surgical outcome was favorable in 22 of 26 patients including 14 who were seizure free. Patients with localized MRI abnormality had a higher probability to be seizure free, with marginal significance (p = 0.062), whereas other diagnostic modalities failed to predict the surgical outcome. In the seizure-free group, localization sensitivity was 64.3% by MRI, 50% by PET, 45.5% by ictal SPECT, and 35.7% by ictal EEG. The concordance rate of the various diagnostic modalities was higher in the seizure-free group than in the non-seizure-free group, although it did not reach statistical significance. CONCLUSIONS: Seizures, in the case of PLE, can manifest themselves in a wider variety of ways than was previously thought. Surgical outcome was favorable in most of the patients. MRI abnormality and concordance of different diagnostic modalities were associated with high seizure-free rate.

Adolescent↗

Is there a visual deficit in dyslexia resulting from a lesion of the right posterior parietal lobe?

Dyslexia has conventionally been attributed to a left hemisphere deficit affecting language skills. However, it has recently been suggested that two-thirds of dyslexic people have a lesion of the right posterior parietal lobe (RPPL) resulting in poor oculo-motor control. It has been reported that neurological patients with RPPL lesions commonly manifest a neglect of the left side of space and this has also been described in clinical observations of 'visual dyslexics'. We investigated this hypothesis with a sample of 53 dyslexic children and 53 controls using a line-bisection task. In the horizontal test condition both groups tended to transect slightly to the left of the midpoint (mean displacement 0.14 mm for controls; 0.4 mm for dyslexics). The result suggests a small right side neglect which, contrary to one report in the literature, is found here in developmental dyslexics as well as controls, and leads to the conclusion that RPPL lesion is unlikely to be a common feature of dyslexia.

Adolescent↗

[Digital agnosia and lesions of the parietal lobe].

130 patients with focal brain damage have been submitted to non-verbal finger identification tasks. The results of this research can be summarized as follows: -when bilateral finger agnosia is studied with non-verbal tasks, no difference can be shown between right and left parietal lesions; -in left brain damaged patients the bilateral form of finger agnosia is generally due to large lesions involving the parietal lobe; -in right brain damaged patients the unilateral form of finger agnosia is almost always due to lesions centered on the parietal region.

Agnosia↗

Localized pain associated with seizures originating in the parietal lobe.

PURPOSE: Ictal pain is a rare symptom of seizures. Epileptic pain may be experienced unilaterally (lateral/ peripheral), cephalically, or in the abdomen. Painful seizures have been associated with seizure origin in both the parietal and the temporal lobes. We report on the different types of epileptic pain and discuss its etiology and possible localizing value. METHODS: We reviewed the records of patients referred to our epilepsy program over the last 6 years. Eight (1.4%) of 573 patients had pain as an early prominent symptom of their seizures. RESULTS: Pain was predominantly unilateral in three patients, cephalic in two, and abdominal in three patients. Seizure onset was in or involving the parietal lobe in all patients, and when the painful symptoms were lateralized, they were contralateral to the side of seizure origin. Parietal lobe seizure origin was determined by both intracranial EEG recording and neuroimaging [magnetic resonance imaging (MRI), ictal single photon emission computed tomography (SPECT)] in five patients, and by both scalp EEG and neuroimaging in three patients. CONCLUSIONS: We conclude that ictal pain is a rare symptom of parietal lobe seizure origin with lateralizing potential.

Abdominal Pain↗

[Anatomical asymmetries of the frontal and parietal lobes (author's transl)].

The anatomical asymmetries of the cerebral hemispheres were described by several investigators. These evaluations were done in postmortem condition. With the introduction of the CT scan, the cytoarchitecture of the human brain in vivo are well appreciated. The purpose of this study is to demonstrate the functional and anatomical asymmetries on the frontal and parietal lobes.

Adolescent↗

31phosphorus magnetic resonance spectroscopy of the frontal and parietal lobes in chronic schizophrenia.

In vivo 31Phosphorus magnetic resonance spectroscopic imaging (31P MRSI) was performed on 20 chronic schizophrenic patients and 16 normal controls to determine if there were specific changes in high energy phosphorus and phospholipid metabolism in the frontal lobes of schizophrenic patients. Phosphorous metabolites were assessed in each of the left and right frontal as well as the left and right parietal lobes. Frontal lobe phosphorous metabolites were also correlated with severity of psychiatric symptomatology as assessed by the Brief Psychiatric Rating Scale (BPRS). Schizophrenics demonstrated higher phosphodiesters (PDE) and lower phosphocreatine (PCr) in both the left and right frontal regions compared to controls. There was also lower left frontal inorganic phosphate (Pi) in the schizophrenic group. No group differences were noted in the left or right parietal regions. In addition, right frontal PDE and right frontal PCr were highly correlated with the hostility-suspiciousness and anxiety-depression subscales of the BPRS. This study provides further support for altered frontal lobe phosphorous metabolism in schizophrenia.

Adult↗

[A case of learning-disabled child with a white matter lesion in the left parietal lobe].

We reported a learning-disabled boy, 7-year-old and right handedness, who was similar to developmental Gerstmann syndrome. Dyscalcuria, right-left disorientation, dysgraphia and finger agnosia were correlated with his sequential disorder which was clearly presented by Kaufman Assessment Battery for Children. In this case, a small infarcted lesion was found in the white matter near the left semioval center on MRI. Hypoperfusion of left parietal lobe was also detected by SPECT. The hemisphere dominant in language was assumed to be on the left side by dichotic listening test. We suggested that left parietal lesion was associated with his higher cortical dysfunction.

Brain Diseases↗

Topographical layout of hand, eye, calculation, and language-related areas in the human parietal lobe.

To identify subdivisions of the human parietal cortex, we collected fMRI data while ten subjects performed six tasks: grasping, pointing, saccades, attention, calculation, and phoneme detection. Examination of task intersections revealed a systematic anterior-to-posterior organization of activations associated with grasping only, grasping and pointing, all visuomotor tasks, attention and saccades, and saccades only. Calculation yielded two distinct activations: one unique to calculation in the bilateral anterior IPS mesial to the supramarginal gyrus and the other shared with phoneme detection in the left IPS mesial to the angular gyrus. These results suggest human homologs of the monkey areas AIP, MIP, V6A, and LIP and imply a large cortical expansion of the inferior parietal lobule correlated with the development of human language and calculation abilities.

Adult↗

Hyperpathia and sensory level due to parietal lobe arteriovenous malformation.

A 30-year-old man experienced the sudden onset of prickly dysesthesia in the perineum followed by a "heavy" sensation in the left lower extremity. There was no headache. He had a hyperpathic response to pinprick and temperature testing below the T-6 dermatome on the left and a decrease of light touch below T-10, also on the left. A small ruptured arteriovenous malformation was found in the right parietal lobe, medially, well above the thalamus, and in the region of the postcentral gyrus. The case provides rare and precise clinicoanatomic correlation of the discrete somatotopic organization of the sensory cortex. Furthermore, it indicates that sensory disturbances, characterized by a segmental level of abnormal sensation suggestive of a spinal cord or medullary lesion and by hyperpathia suggestive of a spinal, medullary, or thalamic localization, can be caused by a suprathalamic parietal deficit.

Adult↗

Unilateral posterior parietal lobe lesions disrupt kinaesthetic representation of forearm orientation.

OBJECTIVE: To apply the lesion method to assess neuroanatomical substrates for judgments of forearm orientation from proprioceptive cues in humans. METHODS: Participants were 15 subjects with chronic unilateral brain lesions and stable behavioural deficits, and 14 neurologically normal controls. Subjects aligned the forearm to earth fixed vertical and trunk fixed anterior-posterior (A-P) axes ("straight ahead"), with the head aligned to the trunk and with head and shoulder orientations varied on each trial. RESULTS: Most subjects with posterior parietal lobe lesions made larger variable errors than controls in aligning the forearm to the earth fixed vertical axis and the trunk A-P axes, whether the head was held upright or oriented in different positions. Lesion subjects and controls made similar constant errors for aligning the forearm to gravitational vertical. Variable error magnitude correlated positively with greater lesion volume of right and left superior parietal lobules (SPL), but not with lesions in other brain areas. Larger variable errors for aligning the forearm to the trunk fixed A-P axis were also correlated with the volume of SPL lesions, but constant error magnitude correlated with larger volume lesions in premotor areas, inferior parietal lobules, and posterior regions of the superior temporal gyri, but not with SPL lesion volume. CONCLUSIONS: The findings suggest that the right and left superior and inferior parietal lobules, posterior superior temporal gyri, and premotor areas play a role in defining higher level coordinate systems for specifying orientation of the right and left forearm.

Adult↗

Relation of EEG alpha background to parietal lobe function in Alzheimer's disease as measured by positron emission tomography and psychometry.

Fourteen patients with Alzheimer's disease were evaluated by psychometric testing, fluorodeoxyglucose positron emission tomography (PET), and EEG. They were divided into two groups according to the EEG findings. Group A (seven patients) had normal alpha backgrounds and group B (seven patients) had decreased alpha backgrounds. Group A had significantly higher WAIS Performance IQ scores (p = 0.005) than group B. Group A also had higher Weschler Memory Scale scores (p = 0.047) and parietal glucose metabolic rates (p = 0.038) than group B, but these differences are not statistically significant given the multiple comparisons made between the two groups. Relative intactness of parietal lobe function, as measured by psychometric testing and PET, appears to correlate with preservation of EEG alpha background. The EEG may be useful in assessing regional cortical involvement or the clinical stage in Alzheimer's disease.

Aged↗

Parietal lobe epileptic focus identified on SPECT-MRI fusion imaging in a case of epilepsia partialis continua.

Epilepsia partialis continua, or "Kozhevnikov syndrome," is a rare condition characterized by persistent localized motor seizures usually localized in a distant limb. It is most often seen in children under 16 years old without gender preference. We report a 12-year-old girl with epilepsia partialis continua who presented to the emergency room after the onset of seizures. Routine electroencephalography (EEG) was performed with no clear ictal localization. Magnetic resonance imaging (MRI) was unremarkable. Ictal single photon emission computed tomography (SPECT) images with Tc-99m exametazime fused with MRI images revealed a parietal lobe epileptic focus within the superior segment of the postcentral gyrus. This case illustrates a rare disorder with an unusual epileptic localization identified by SPECT-MRI fusion.

Adolescent↗

The central role of the parietal lobes in consciousness.

There are now various approaches to understand where and how in the brain consciousness arises from neural activity, none of which is universally accepted. Difficulties among these approaches are reviewed, and a missing ingredient is proposed here to help adjudicate between them, that of "perspectivalness." In addition to a suitable temporal duration and information content of the relevant bound brain activity, this extra component is posited as being a further important ingredient for the creation of consciousness from neural activity. It guides the development of what is termed the "Central Representation," which is supposed to be present in all mammals and extended in humans to support self-consciousness as well as phenomenal consciousness. Experimental evidence and a theoretical framework for the existence of the central representation are presented, which relates the extra component to specific buffer working memory sites in the inferior parietal lobes, acting as attentional coordinators on the spatial maps making up the central representation. The article closes with a discussion of various open questions.

Attention↗