Parieto-occipital Lesions Research Articles

POLG1 manifestations in childhood

Mitochondrial DNA polymerase γ (POLG1) mutations in children often manifest as Alpers syndrome, whereas in adults, a common manifestation is mitochondrial recessive ataxia syndrome (MIRAS) with severe epilepsy. Because some patients with MIRAS have presented with ataxia or epilepsy already in childhood, we searched for POLG1 mutations in neurologic manifestations in childhood. We investigated POLG1 in 136 children, all clinically suspected to have mitochondrial disease, with one or more of the following: ataxia, axonal neuropathy, severe epilepsy without known epilepsy syndrome, epileptic encephalopathy, encephalohepatopathy, or neuropathologically verified Alpers syndrome. Seven patients had POLG1 mutations, and all of them had severe encephalopathy with intractable epilepsy. Four patients had died after exposure to sodium valproate. Brain MRI showed parieto-occipital or thalamic hyperintense lesions, white matter abnormality, and atrophy. Muscle histology and mitochondrial biochemistry results were normal in all. POLG1 analysis should belong to the first-line DNA diagnostic tests for children with an encephalitis-like presentation evolving into epileptic encephalopathy with liver involvement (Alpers syndrome), even if brain MRI and morphology, respiratory chain activities, and the amount of mitochondrial DNA in the skeletal muscle are normal. POLG1 analysis should precede valproate therapy in pediatric patients with a typical phenotype. However, POLG1 is not a common cause of isolated epilepsy or ataxia in childhood.

The impact of stroke on emotional intelligence

BackgroundEmotional intelligence (EI) is important for personal, social and career success and has been linked to the frontal anterior cingulate, insula and amygdala regions.AimTo ascertain which stroke lesion sites impair emotional intelligence and relation to current frontal assessment measurements.MethodsOne hundred consecutive, non aphasic, independently functioning patients post stroke were evaluated with the Bar-On emotional intelligence test, "known as the Emotional Quotient Inventory (EQ-i)" and frontal tests that included the Wisconsin Card Sorting Test (WCST) and Frontal Systems Behavioral Inventory (FRSBE) for correlational validity. The results of a screening, bedside frontal network syndrome test (FNS) and NIHSS to document neurological deficit were also recorded. Lesion location was determined by the Cerefy digital, coxial brain atlas.ResultsAfter exclusions (n = 8), patients tested (n = 92, mean age 50.1, CI: 52.9, 47.3 years) revealed that EQ-i scores were correlated (negatively) with all FRSBE T sub-scores (apathy, disinhibition, executive, total), with self-reported scores correlating better than family reported scores. Regression analysis revealed age and FRSBE total scores as the most influential variables. The WCST error percentage T score did not correlate with the EQ-i scores. Based on ANOVA, there were significant differences among the lesion sites with the lowest mean EQ-i scores associated with temporal (71.5) and frontal (87.3) lesions followed by subtentorial (91.7), subcortical gray (92.6) and white (95.2) matter, and the highest scores associated with parieto-occipital lesions (113.1).Conclusions1) Stroke impairs EI and is associated with apathy, disinhibition and executive functioning. 2) EI is associated with frontal, temporal, subcortical and subtentorial stroke syndromes.

Right posterior cortical functions in a tumour patient series

It is standardly believed that the localisation of cognitive function by means of impairments arising from cortical tumour is not possible as the functional defects that result are mild and unspecific. These assumptions were not supported in an investigation of four processes generally sensitive to right posterior cortical lesions, when patients with parieto-occipital lesions were compared with prefrontal ones. In three of the tests loading on the individual processes – Reaching Accuracy, Star Cancellation, Fragmented Letters and Cube Analysis – parieto-occipital impairments were found in the basic groups analysis and this was so in the right-hemisphere group. More critically, in these tests Lesion Behaviour Mapping showed the critical lesion site for the tests to have relatively little overlap with those of the other tests, indicating that the cognitive effects were not widespread and diffuse. In addition, in three of the tests the critical lesion sites fitted localisations arrived from other procedures. Patients with high-grade tumours performed considerably worse than those with low-grade tumours in only two of the tests (Star Cancellation, Cube Analysis) particularly in the right parieto-occipital group. In three (Reaching Accuracy, Star Cancellation, Cube Analysis) there was a deterioration with the operation specifically in the low-grade tumour patients. It is suggested that a tumour patient series may provide converging evidence for the localisation of a function initially obtained by some other procedure.

Development of a Partial Balint's Syndrome in a Congenitally Deaf Patient Presenting as Pseudo-Aphasia

We present a 56 year-old, right-handed, congenitally deaf female who exhibited a partial Balint's syndrome accompanied by positive visual phenomena restricted to her lower right visual quadrant (e.g., color band, transient unformed visual hallucinations). Balint's syndrome is characterized by a triad of visuo-ocular symptoms that typically occur following bilateral parieto-occipital lobe lesions. These symptoms include the inability to perceive simultaneous events in one's visual field (simultanagnosia), an inability to fixate and follow an object with one's eyes (optic apraxia), and an impairment of target pointing under visual guidance (optic ataxia). Our patient exhibited simultanagnosia, optic ataxia, left visual field neglect, and impairment of all complex visual-spatial tasks, yet demonstrated normal visual acuity, intact visual fields, and an otherwise normal neurocognitive profile. The patient's visuo-ocular symptoms were noticed while she was participating in rehabilitation for a small right pontine stroke. White matter changes involving both occipital lobes had been incidentally noted on the CT scan revealing the pontine infarction. As the patient relied on sign language and reading ability for communication, these visuo-perceptual limitations hindered her ability to interact with others and gave the appearance of aphasia. We discuss the technical challenges of assessing a patient with significant barriers to communication (e.g., the need for a non-standardized approach, a lack of normative data for such special populations), while pointing out the substantial contributions that can be made by going beyond the standard neuropsychological test batteries.

MRI and FDG PET/CT findings in a case of probable Heidenhain variant Creutzfeldt-Jakob disease

Creutzfeldt-Jakob disease (CJD) is a neurodegenerative disease caused by the accumulation of a pathogenic isoform of a prion protein in neurons that is responsible for subacute dementia. The Heidenhain variant is an atypical form of CJD in which visual signs are predominant. This is a report of the case of a 65-year-old man with probable CJD of the Heidenhain variant, with topographical concordance between findings on magnetic resonance imaging (MRI) and 18F-fluorodeoxyglucose (FDG) photopenic areas on positron emission tomography (PET)/computed tomography (CT) for cortical parietooccipital lesions.

Symptomatic Parieto-Occipital Epilepsy as Sequela of Perinatal Asphyxia

Perinatal hypoxic-ischemic encephalopathy in term infants has been well-documented as a cause of selective brain damage over the parasagittal brain regions in cases of partial asphyxia. We describe 10 patients (7 boys, 3 girls) who developed normally after perinatal asphyxia, and who later experienced parieto-occipital epilepsy. We retrospectively reviewed medical records, electroencephalograms, and neuroimaging findings. All patients had a history of perinatal asphyxia requiring intensive care. Subsequent developmental milestones were apparently normal. Seizures started at ages ranging from 10 to 168 months (mean, 72 months). The seizures comprised complex partial seizures with visual symptomatology in 5 cases, complex partial seizures without visual symptomatology in 4 cases, and focal motor seizures with secondary generalization in the remaining case. Brain magnetic resonance imaging demonstrated localized parieto-occipital lesions in 9 cases, and normal findings in the remaining one. Electroencephalograms revealed predominantly occipital foci in 8. In all patients, the epileptogenic foci involved either unilateral or bilateral parieto-occipital regions. Intelligence quotients and visuospatial cognitive functions were impaired in 7 patients. Seizures were finally controlled in only 4 patients. Symptomatic parieto-occipital epilepsy caused by mild perinatal hypoxic-ischemic encephalopathy is sometimes pharmaco-resistant and accompanied by mild cognitive and visuospatial impairments.

Perception and Understanding of Others' Actions and Brain Connectivity

ABSTRACT Perception and understanding of dispositions and intentions of others through their actions are of immense importance for adaptive daily-life behavior and social communication. Here we ask whether, and, if so, how this ability is impaired in adolescents who were born premature and suffer early periventricular damage, periventricular leukomalacia (PVL) that affects brain connectivity. The visual event arrangement (EA) task was administered to PVL patients and two control groups, premature-born and term-born adolescents without brain abnormalities on a magnetic resonance imaging scan. Performance on the EA task was significantly lower in PVL patients as compared with controls. No difference was found between premature-born participants without lesions and term-born controls. Performance on the EA task was inversely related to the volumetric extent of lesions in the parieto-occipital regions of both hemispheres and, in particular, to the right temporal periventricular lesions. Whereas our earlier work reveals that compromised visual processing of biological motion, impairments in visual navigation, and other visual-perceptual disabilities in PVL patients are associated with parieto-occipital lesions, difficulties in the visual EA task solely are specifically linked to the right temporal periventricular lesions. For the first time, we show that the severity of the right temporal PVL can serve as a predictor of the ability for perception and understanding of others' actions. We assume that impairments in this ability in PVL patients are caused by disrupted brain connectivity to the right temporal cortex, a key node of the social brain.

Perception and Understanding of Others' Actions and Brain Connectivity

Perception and understanding of dispositions and intentions of others through their actions are of immense importance for adaptive daily-life behavior and social communication. Here we ask whether, and, if so, how this ability is impaired in adolescents who were born premature and suffer early periventricular damage, periventricular leukomalacia (PVL) that affects brain connectivity. The visual event arrangement (EA) task was administered to PVL patients and two control groups, premature-born and term-born adolescents without brain abnormalities on a magnetic resonance imaging scan. Performance on the EA task was significantly lower in PVL patients as compared with controls. No difference was found between premature-born participants without lesions and term-born controls. Performance on the EA task was inversely related to the volumetric extent of lesions in the parieto-occipital regions of both hemispheres and, in particular, to the right temporal periventricular lesions. Whereas our earlier work reveals that compromised visual processing of biological motion, impairments in visual navigation, and other visual-perceptual disabilities in PVL patients are associated with parieto-occipital lesions, difficulties in the visual EA task solely are specifically linked to the right temporal periventricular lesions. For the first time, we show that the severity of the right temporal PVL can serve as a predictor of the ability for perception and understanding of others' actions. We assume that impairments in this ability in PVL patients are caused by disrupted brain connectivity to the right temporal cortex, a key node of the social brain.

Comparison of SPECT findings and neuropsychological sequelae in carbon monoxide and organophosphate poisoning

Abnormal regional cerebral blood flow in patients with acute carbon monoxide (CO) and organophosphate (OP) poisoning was examined using 99m Tc-hexamethylpropylene amine oxime (HMPAO) brain single photon emission computed tomography (SPECT) in fourteen patients. We evaluated the predictive significance of acute phase brain SPECT findings for long-term neuropsychological sequelae. Changes were found in the frontal, temporal, parietal lobes within the first week after both types of poisoning. The distribution of the hypoperfused cerebral areas as demonstrated by 99m Tc-HMPAO imaging was similar in the two groups during the acute phase. Neuropsychological sequelae developed in five patients poisoned with OP and six with CO. Patients who had SPECT findings heterogeneously or in the temporal or frontal lobes displayed disorientation. Those with fronto-parietal and frontal lobe changes displayed mental confusion. Parkinsonism also was observed in patients with parieto-occipital, parietal and frontal lobe lesions. The distribution of these lesions appears to predict the long term sequelae of these poisonings, though additional studies with larger numbers of patients are needed to confirm the role of SPECT imaging in both OP and CO poisonings.

Fundamental Requirements for Primary Visual Perception

A novel perspective for the necessary and sufficient conditions for primary visual perception is proposed based upon relating recent discoveries from the visual sciences to relevant foundational neurological observations. This analysis suggests that a fundamental requirement for the emergence of normal primary visual perception is the coupling between the early visual cortices in the occipital lobe subserving image content with specific areas in the parietal lobe subserving selective attention, representations of extrapersonal space, the body schema, and the initiation of perceptual ownership. Fully intact primary visual perception, which includes the normal placement of image content within extrapersonal space, seems to require at each instant a mutually consistent completeness and corresponding removal of ambiguities in each of the linked neural representations subserving image, space and self. Experimental approaches that could either invalidate or strengthen the proposed framework are suggested as well as opportunities to differentiate some aspects of normal primary visual perception from the severely compromised visual experience that survives bilateral parieto-occipital lesions (Balint's syndrome) when visual experience may persist for single but unlocalizable objects.

Electroclinical and imaging findings in ulegyria and epilepsy: a study on 25 patients

Purpose:Ulegyria refers to cerebral cortex scarring, which results from a perinatal ischaemic brain injury. It presents with a characteristic gyral pattern: small circumvolutions with atrophy at sulci bottom and spared...

Functional dissociation of saccade and hand reaching control with bilateral lesions of the medial wall of the intraparietal sulcus: Implications for optic ataxia

The posterior parietal cortex (PPC) is essential for the integration of visuomotor information during visually guided reaching. Studies in macaque monkeys have demonstrated a functional specialisation around the intraparietal sulcus (IPS) with a more medial representation of hand movements (“parietal reach region”) and a more lateral representation of saccadic eye movements (lateral intraparietal area, LIP). Here we present evidence for the validity of this concept with respect to the human parietal cortex. We recorded isolated and combined goal-directed eye–hand movements in normal control subjects and in a patient with bilateral parieto-occipital lesions and incomplete Balint's syndrome including severe optic ataxia (misreaching to visual targets). Brain lesions in the patient were caused by acute posterior leucoencephalopathy in association with aortic surgery because of Takayasu's arteritis. MRI scans showed bilateral line-shaped hemorrhagic lesions, restricted to the cortex at the medial banks of the intraparietal sulcus, but leaving its lateral banks largely intact. In the patient visually guided reaching was significantly dysmetric, whereas the metrics of visually guided saccades were within normal limits. Dysmetria was more pronounced for the right visual field, with a gross hypermetria. Variability of the movement improved when a delay of 5 or 10 s was introduced between target presentation and movement execution. Lesion data support the concept of a functional specialisation around the human IPS: The cortex medial to the IPS predominantly controls rapid goal-directed reaching movements, comparable to the parietal reach region in monkeys, whereas saccadic eye movements appear to be controlled rather by the cortex lateral to the IPS.

Two Cases of Hypertensive Encephalopathy Involving the Brainstem

Hypertensive encephalopathy is a medical emergency whose clinical manifestations are usually associated with bilateral parieto-occipital lesions. Predominant brainstem edema without accompanying occipital lesions is rare in hypertensive encephalopathy and usually occurs in patients with secondary hypertension. We describe the clinical and radiological features of two patients with reversible hypertensive brainstem encephalopathy. Both patients had chronic renal failure, but the extensive neuroimaging abnormalities revealed few clinical features of brainstem involvement. The clinical findings and neuroimaging abnormalities resolved once the hypertension was treated.

Hypertensive Brainstem Encephalopathy Without Parieto-occipital Lesion-Two Case Reports-

Two patients presented with malignant hypertension associated with encephalopathy predominantly manifesting as brainstem lesion. T(2)-weighted and fluid-attenuated inversion recovery magnetic resonance (MR) imaging revealed diffuse hyperintense areas in the pons and scattered lesions in the cerebellum, basal ganglia, and cerebral subcortex without parieto-occipital lesions. Diffusion-weighted MR imaging demonstrated these lesions as normal intensity, indicating vasogenic edema. These lesions resolved rapidly once hypertension was controlled. Review of clinical findings for 14 other patients with hypertensive brainstem encephalopathy without parieto-occipital lesions suggested that anterior circulation structures supplied by the carotid artery are frequently involved in such patients.

Biological motion processing in adolescents with early periventricular brain damage

The developing brain is traditionally viewed to possess a great compensatory potential. Here we ask whether visual processing of point-light displays depicting human walking is compromised in adolescents who were born premature (between 27 and 33 gestation weeks) and suffer early bilateral damage to periventricular brain regions. Combining psychophysics with volumetric analysis of structural magnetic resonance imaging (MRI), we found that even relatively small periventricular parieto-occipital lesions may result in long-lasting breakdown of visual processing of point-light displays. Analysis of receiver operating characteristic (ROC) curves revealed higher susceptibility of the patients’ perceptual system to camouflage of a point-light figure. The lack of difference in sensitivity between former preterms with normal MRI scan and term-born controls indicates that perceptual deficiencies in patients with periventricular leukomalacia (PVL) are not simply due to premature birth. Most importantly, sensitivity in patients even with mild PVL was lower than in both control groups. Display 180° inversion in the image plane, which is known to impair processing of point-light displays, resulted in a substantial reduction of sensitivity so that it no longer differed between the groups. Despite the social and ecological significance of human locomotion, the capacity of the brain to detect biological motion is substantially modulated by periventricular lesions even if they occur very early in life. The findings point to specific restrictions on the brain's spontaneous compensatory plasticity in perceptual development.

Deep White Matter Pathologic Features in Watershed Regions

Myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome typically manifests in adults younger than 40 years with encephalopathy, stroke-like episodes, and lactic acidosis. Magnetic resonance imaging (MRI) abnormalities typically involve the cortical gray and the adjacent subcortical white matter. To describe a 58-year-old woman diagnosed with MELAS who was initially seen with acute myopathy, cardiac ischemia, psychosis, and MRI changes in a watershed distribution. Initial MRI of the brain showed the characteristic parieto-occipital gray matter lesions involving the adjacent white matter. Follow-up MRI revealed striking deep white matter involvement in a watershed distribution. A cerebral angiogram and thorough hypercoagulable workup results were normal. Electromyography showed acute denervation and myopathy. A muscle biopsy specimen revealed ragged red and cytochrome-c oxidase-negative fibers. Mitochondrial DNA analysis revealed an A3243G mutation. Myopathy, encephalopathy, lactic acidosis, and stroke-like episodes should be considered in older patients with myopathy, cardiomyopathy, encephalopathy, and unaccountable MRI findings. Watershed pathologic features are a rare pattern of cerebral involvement in MELAS.

Symptomatic occipital lobe epilepsy following neonatal hypoglycemia

This study reports on the clinical, electrophysiologic, and neuroradiologic aspects of patients with epilepsy secondary to neonatal hypoglycemia. Fifteen patients with epilepsy and/or posterior cerebral lesions, and neonatal hypoglycemia were studied in the epilepsy clinic between February 1990 and March 2003. The mean age was 12 years. The different types of neonatal hypoglycemia were as follows: four patients had transitional-adaptive, seven classic transient, two secondary-associated, and two severe recurrent hypoglycemia. As to epilepsy, we recognized a larger group of 12 patients characterized by focal seizures and posterior abnormalities on the electroencephalogram, the majority of whom had a good outcome, and a second group of two patients presenting electroclinical features of encephalopathy with refractory seizures. All patients except two manifested parieto-occipital lesions on neuroradiologic images. Neurologic examination was normal in one patient. Six patients had microcephaly; eight manifested visual disturbances. Fourteen patients were mentally retarded. One had a pervasive developmental disorder. This study indicates neonatal hypoglycemia may cause posterior cerebral lesions, abnormal findings at neurologic examination, and symptomatic epilepsy, most frequently occipital lobe epilepsy, usually with a good prognosis, and occasionally epileptic encephalopathy with refractory seizures. MRI studies are essential to define the characteristics of cerebral lesions after neonatal hypoglycemia.

Global aphasia without hemiparesis: lesion analysis and its mechanism in 11 Korean patients

Background: Global aphasia without hemiparesis (GAWH) is a rare stroke syndrome. This study localized the lesion and examined the pathogenic mechanism in Korean patients with GAWH, and investigated whether areas of extensive hypoperfusion existed outside the diffusion-weighted imaging (DWI) lesions seen in these patients. Material and methods: Eleven patients were diagnosed with aphasia using the Western Aphasia Battery. To identify decreased perfusion, which might be functionally relevant to aphasia but not detected by DWI, single photon emission tomography (SPECT) was performed in five patients. To uncover the possible pathogenic mechanisms of ischemic stroke, vascular and cardiologic work-ups were performed in all of the patients. Results: The lesions seen on DWI varied, and included both inferior frontal and superior temporal (three), isolated inferior frontal (four) or superior temporal (one), subcortical (two), and even parieto-occipital (one) lesions. Brain SPECT did not reveal an extensive lesion of the peri-sylvian area outside the DWI lesion in any of the patients, except one with the subcortical lesions. Conclusion: Our results indicate that a single lesion in different locations may be sufficient to produce GAWH, and the lesion profile and stroke mechanism in GAWH are heterogeneous, suggesting that lesions to an area of complex functional anatomy result in aphasia.

Hypertensive brain stem encephalopathy: clinically silent massive edema of the pons

Hypertensive encephalopathy is a medical emergency whose clinical manifestations are associated with bilateral parieto-occipital lesions. We describe a case of hypertensive brainstem encephalopathy in which high blood pressure was accompanied only by nuchal headaches of violent onset. T2-weighted magnetic resonance images showed hyperintensity and edema of the pons without any parietooccipital lesions, but with hyperintense lesions at the level of the basal nuclei, insula and temporal lobes. The lesions rapidly regressed once the hypertension had been controlled.

Phenotype assignment in symptomatic female carriers of X-linked adrenoleukodystrophy.

However, only very few studies have systematically investigated the extent and distribution of nervous and endocrine system involvement in female carriers of X-ALD. To define the phenotype in symptomatic female carriers of X-ALD we performed a prospective study including eight symptomatic women who were followed for a mean period of 3.4+/-1.8 years (range 1-6) using standardized clinical examination protocols, magnetic resonance imaging and spectroscopy, evoked potential studies including visual, brainstem auditory, somatosensory and magnetic evoked potentials, neurographic recordings and endocrine studies. Spastic paraparesis and decreased vibration sense in the lower extremities were the most frequent clinical findings. Slightly hyperintense symmetric parieto-occipital white matter lesions on magnetic resonance imaging were detectable in two of seven cases, and the N-acetylaspartate/choline ratios on magnetic resonance spectroscopy were decreased in three of seven patients. P40 latencies were abnormal in all patients, and central motor conduction times to the lower extremities in seven of eight patients. Prolonged latencies of brainstem auditory evoked potential waves III-V or interpeak latencies of waves I-III, I-V and III-V were detectable in all patients. The degree of walking impairment was positively correlated with the duration of clinical disease (r=0.58, P < 0.05) and inversely correlated with the N-acetylaspartate/choline ratios (r=0.85; P < 0.05). Neurographic recordings revealed only subtle abnormalities, suggesting that nervous system involvement in symptomatic female carriers of X-ALD is confined mainly to the central nervous system. No evidence of adrenal insufficiency was detected in any of the patients.