Right parietal lobe syndrome as a clinical variant of Creutzfeldt-Jakob disease

We report a 57‐year‐old patient with Creutzfeldt‐Jakob disease that initially presented with right parietal lobe syndrome. He featured early dystonic and hemiparetic posture of the left upper limb, finger agnosia, geographic disorientation and acalculia and developed myoclonus from the left upper extremity and right‐sided periodic synchronized discharges. He died 2 years and 3 months later. Brain autopsy revealed a marked reduction in brain weight, extensive cortical spongiform changes and white matter degeneration. Immunolabeled prion proteins were deposited diffusely in the neuropil. Accentuation of the cortical change was unclear but white matter degeneration was more severe in the right parietal lobe than in the left parietal lobe. Right parietal lobe syndrome is rarely reported as an initial symptom of Creutzfeldt‐Jakob disease and can be a clinical variant of the disease.     

Single photon emission computed tomography using 99mTc-HM-PAO in the routine evaluation of Alzheimer's disease

Regional cerebral blood flow was studied in 7 patients with clinically suspected Alzheimer's disease and 10 normal controls by single photon computed emission tomography (SPECT) using HM-PAO. All patients with Alzheimer's disease and no controls had parietal lobe hypoperfusion which was usually bilateral. In patients with more severe dementia hypoperfusion extended into the frontal lobes. Parietal lobe hypoperfusion corresponds to parietal lobe degeneration which is the one of the first neocortical regions to show the typical degenerative changes of Alzheimer's disease. SPECT with HM-PAO is a non-invasive investigation available in most nuclear medicine departments and complements existing tests in the routine evaluation of patients presenting with dementia.     

Global spatial disorientation: Clinico-pathologic correlations

Two patients presenting with the acute onset of bilateral parietal lobe damage showed initially the features of Balint's syndrome. After most of its manifestations had cleared, both patients exhibited severe disorders of spatial orientation: acoustic ataxia, inability to localize objects in space. In addition, 1 patient showed a topographical disorientation and abnormalities of whole body movements. This patient came to post-mortem examination, which revealed bilateral and fairly symmetrical old and recent infarctions of the superior parietal lobules.In the light of these observations and previous reports, it is suggested that the reported abnormalities of whole body movements can be explained on the basis of a visuo-motor intrahemispheric disconnection due to the bilateral lesion of the dorsal parietal lobe. In addition, the global spatial disorientation is analyzed and is thought to be the manifestation of a derangement of a specific function centered in the parietal lobe. Moreover, it is pointed out that topographic disorientation does not require the concomitant failure of oculomotor mechanisms for its production.The topography of the anatomical lesion is considered in relation to current concepts on brain damage after severe hypotension and cardiac arrest. It is concluded that this group of patients is most likely at risk of developing behavioural abnormalities akin to the ones here reported.     

Hemispheric preference in visuospatial processing: a complementary approach with fMRI and lesion studies

Historically, the left cerebral hemisphere has been considered specialized for language, whereas the right cerebral hemisphere is aligned with spatial processes. However, studies have called into question adherence to this model and suggested that both hemispheres participate in language and spatial cognition. Using functional Magnetic Resonance Imaging (fMRI) and human brain lesion studies, we determined whether these complementary techniques could clarify issues of hemispheric dominance. Using a modified Benton Judgement of Line Orientation (JLO) test, considered a relatively pure spatial processing task, we found robust and significant (p < 0.0005) bilateral superior parietal lobe activation on fMRI in ten right-handed male adult volunteers. This was corroborated by lesion data in a cohort of 17 patients who showed significant JLO impairments after either right or left parietal lobe damage, with right parietal damage associated with somewhat more severe deficit. Detailed wavelet analysis of the fMRI time-series did, however, reveal a more dominant role of the right parietal lobe in "kick-starting" the task. To our knowledge, this is a novel way of using fMRI to address functional hemispheric differences in a cognitive task that is known to have bilateral representation.     

额颞部重度颅脑损伤扩大翼点入路手术治疗分析

目的探讨扩大翼点入路治疗额颞部重度颅脑损伤的临床价值。方法48例额颞部重度颅脑损伤患者均采用扩大翼点入路手术治疗方法。扩大翼点入路即在翼点入路基础上扩大暴露范围，包括额底、颞底及额颞顶较大范围。扩大翼点入路结合硬膜扩大缝合，有时采用浮动骨瓣等方法。结果康复良好20例（41．6％），中度残废9例（18．8％），重度残废7例（14．7％），植物生存4例（8．3％），死亡8例（16．7％），死亡原因为严重脑干损伤、休克、严重脑肿胀及呼吸、循环衰竭。结论扩大翼点入路手术治疗额颞部重度颅脑损伤是比较理想的入路，可减少死亡率和伤残率，提高生存质量。     

Autopsy case of atypical type of alzheimer's disease clinically diagnosed as corticobasal degeneration]

A 60-year-old, right-handed man developed gait disturbance. He also had difficulty in dressing and demonstrated depressive status, but did not have memory impairment. He was diagnosed as having corticobasal degeneration (CBD) because of right cortical atrophy and contralateral movement disorder. He died at the age of 69. The pathological diagnosis was not CBD but Alzheimer's disease. The brain showed severe atrophy, especially in the right superior parietal lobe and postcentral gyrus. The cortical lesion was most marked in the right parietal lobe within the neocortex, and was more severe than that in the limbic area. Clinically this patient was highly suspected to have CBD. This case, however, is categorized into atypical Alzheimer's disease with a focal cortical syndrome.     

Is the posterior parietal lobe involved in working memory retrieval? Evidence from patients with bilateral parietal lobe damage

Neuroimaging evidence suggests that the parietal lobe has an important role in memory retrieval, yet neuropsychology is largely silent on this topic. Recently, we reported that unilateral parietal lobe damage impairs various forms of visual working memory when tested by old/new recognition. Here, we investigate whether parietal lobe working memory deficits are linked to problems at retrieval. We tested two patients with bilateral parietal lobe damage in a series of visual working memory tasks that probed recall and old/new recognition. Stimuli were presented sequentially and several stimulus categories were tested. The results of these experiments show that parietal lobe damage disproportionately impairs old/new recognition as compared to cued recall across stimulus categories. The observed performance dissociation suggests that the posterior parietal lobe plays a particularly vital role in working memory retrieval.     

Double dissociation of Hangul and Hanja reading in Korean patients with stroke

The orthographic system of the Korean language consists of both phonogram (Hangul) and ideogram (Hanja). We report 2 patients who revealed selective impairment in reading either of orthographies after the brain damages. YJ, a 67-year-old man, showed Broca's aphasia and severe apraxia of speech after a stroke in the left inferior parietal lobe. He demonstrated predominant difficulties in reading phonogram. KS, a 51-year-old woman, had an intracerebral hemorrhage in the left parietal lobe. She showed anomic aphasia and a selective impairment on reading ideogram. These findings support the notion that recognition of visual words is processed in different ways depending on the characteristics of orthographic systems.     

Frontoparietal cortical atrophy with gliosis in the gray matter of cerebral cortex: case report

The case of a patient who suffered from progressive amnesia, depressive humor, language and visuospatial disturbances, and hallucination episodies with interference at the daily living activities is reported. She had moderate neuropsychological diffuse deficits at the first examination, especially at the executive and visuo-constructive functions. Her cerebrospinal fluid test presented high total protein. Magnetic resonance image showed slight white matter increase in periventricular, semi-oval center bilateral and left external capsule regions, besides light frontal and parietal lobe atrophy, bilaterally. Brain single photon emission computerized tomography revealed both a bilateral moderate frontal and a severe parietal lobe hypoperfusion, especially on the left side. Macroscopic examination showed cortical atrophy, severe on the frontal, moderate on the parietal and mild on the posterior third temporal lobes, bilaterally. There was a slight atrophy on the neostriatum in the basal ganglia. The histopathological findings of the autopsy showed severe neuronal loss with intensive gemioscytic gliosis and variable degrees of status spongiosus in cortical layer. Hematoxylin-eosin and Bielschowsky staining did not show neuronal swelling (balooned cell), argyrophilic inclusion (Pick's bodies), neurofibrillary tangles nor senile plaques. Immunohistochemical staining for anti-ubiquitin, anti-tau, anti-beta-amyloide, and anti-prion protein were tested negative.     

Is the parietal lobe necessary for recollection in humans?

An intriguing puzzle in cognitive neuroscience over recent years has been the common observation of parietal lobe activation in functional neuroimaging studies during the performance of human memory tasks. These findings have surprised scientists and clinicians because they challenge decades of established thinking that the parietal lobe does not support memory function. However, direct empirical investigation of whether circumscribed parietal lobe lesions might indeed be associated with human memory impairment has been lacking. Here we confirm using functional magnetic resonance imaging that significant parietal lobe activation is observed in healthy volunteers during a task assessing recollection of the context in which events previously occurred. However, patients with parietal lobe lesions that overlap closely with the regions activated in the healthy volunteers nevertheless exhibit normal performance on the same recollection task. Thus, although the processes subserved by the human parietal lobe appear to be recruited to support memory function, they are not a necessary requirement for accurate remembering to occur.     

Left hemispatial visual neglect associated with a combined right occipital and splenial lesion: another disconnection syndrome

Damage to the left occipital lobe and the splenium or forceps major is often associated with pure alexia, thought to be an occipital-temporoparietal disconnection syndrome. A patient with the parallel lesion, a combined right occipital and splenial lesion, showed severe left-sided visual spatial neglect, but no significant neglect in other sensory modalities. This visual neglect might be related to a disconnection between the visual information processed by the left occipital lobe and the right posterior temporal-inferior parietal areas that mediate attention in the left hemispace.     

Frontal lobe atrophy is associated with small vessel disease in ischemic stroke patients

Background

The pathogenesis of frontal lobe atrophy (FLA) in stroke patients is unclear. We aimed to ascertain whether subcortical ischemic changes were more associated with FLA than with parietal lobe atrophy (PLA) and temporal lobe atrophy (TLA).

Methods

Brain magnetic resonance images (MRIs) from 471 Chinese ischemic stroke patients were analyzed. Lobar atrophy was defined by a widely used visual rating scale. All patients were divided into non-severe, mild–moderate, and severe atrophy of the frontal, parietal, and temporal lobe groups. The severity of white matter lesions (WMLs) was rated with the Fazekas’ scale. Clinical and radiological features were compared among the groups. Subsequent logistic regressions were performed to determine the risk factors of atrophy and severe atrophy of the frontal, parietal and temporal lobes.

Results

The frequency of FLA in our cohort was 36.9% (174/471). Severe FLA occurred in 30 (6.4%) patients. Age, previous stroke, and periventricular hyperintensities (PVH) (odds ratio (OR) = 1.640, p = 0.039) were independent risk factors of FLA. Age and deep white matter hyperintensities (DWMH) (OR = 3.634, p = 0.002) were independent risk factors of severe FLA. PVH and DWMH were not independent risk factors of PLA and TLA.

Conclusion

Frontal lobe atrophy in ischemic stroke patients may be associated with small vessel disease. The association between WMLs and FLA was predominant over atrophy of the parietal and temporal lobes, which suggests that the frontal lobe may be vulnerable to subcortical ischemic changes.     

Long‐term seizure outcome following epilepsy surgery in the parietal lobe: a meta‐analysis

Aim. Due to a limited number of patients with drug‐resistant parietal lobe epilepsy in surgical series, there are insufficient data about long‐term seizure outcome following surgery restricted to the parietal lobe. We performed a meta‐analysis to asses long‐term outcomes in patients with parietal lobe epilepsy who underwent surgery confined to the parietal lobe or resection with major involvement of the parietal cortex. Methods. An English language literature search for studies on parietal lobe surgery and outcome was conducted using the MEDLINE database, followed by a manual search based on specific criteria. An inverse variance random effect meta‐analysis model was used to estimate the pooled proportion of Engel Class I. Meta‐regression models were used to examine the association between outcome and potential predictors. Results. The search yielded seven retrospective studies with a total sample size of 253 patients (mean follow‐up: 104.9±74.8 months). Following surgery, Engel Class I surgical outcome was achieved in 62.4% (95% CI: 0.492–0.755). Two independent predictors were identified for positive long‐term outcome: interictal EEG localized to the parietal region (p=0.007) and the presence of tumour (p=0.022). Conclusion. Following surgery confined to the parietal lobe or resection with major involvement of the parietal cortex, the long‐term prognosis of patients with parietal lobe epilepsy is favourable.     

Parietal cortex matters in Alzheimer's disease: an overview of structural, functional and metabolic findings

Atrophy of the medial temporal lobe, especially the hippocampus and the parahippocampal gyrus, is considered to be the most predictive structural brain biomarker for Alzheimer's Dementia (AD). However, recent neuroimaging studies reported a possible mismatch between structural and metabolic findings, showing medial temporal lobe atrophy and medial parietal hypoperfusion as biomarkers for AD. The role of the parietal lobe in the development of AD is only recently beginning to attract attention. The current review discusses parietal lobe involvement in the early stages of AD, viz. mild cognitive impairment, as reported from structural, functional, perfusion and metabolic neuroimaging studies. The medial and posterior parts of the parietal lobe seem to be preferentially affected, compared to the other parietal lobe parts. On the basis of the reviewed literature we propose a model showing the relationship between the various pathological events, as measured by different neuroimaging techniques, in the development of AD. In this model myelin breakdown is a beginning of the chain of pathological events leading to AD pathology and an AD diagnosis.     

Parietal ataxic hemiparesis

Ataxia in the parietal lobe is rarely described. A case of ataxia hemiparesis due to a parietal lobe infarction is described and pathophysiology is discussed.     

Left hemispatial visual neglect associated with a combined right occipital and splenial lesion: Another disconnection syndrome

Damage to the left occipital lobe and the splenium or forceps major is often associated with pure alexia, thought to be an occipital-temporoparietal disconnection syndrome. A patient with the parallel lesion, a combined right occipital and splenial lesion, showed severe left-sided visual spatial neglect, but no significant neglect in other sensory modalities. This visual neglect might be related to a disconnection between the visual information processed by the left occipital lobe and the right posterior temporal-inferior parietal areas that mediate attention in the left hemispace.     

Interlocking finger test: a bedside screen for parietal lobe dysfunction

This study sought to determine the utility of an interlocking finger task in screening for parietal lobe dysfunction. The ability of 69 patients to imitate a standardised set of four interlocking finger figures was compared with concurrent performance on formal neurocognitive tests. Poor interlocking finger test scores correlated most highly with standard measures of parietal lobe dysfunction. In addition, an analytical model of parietal dysfunction indicated the interlocking finger test was similar to, if not better than, standard tests of parietal lobe dysfunction. Attempts to imitate these figures should serve as a fast and simple screen of parietal lobe dysfunction.     

Hemidystonia secondary to carotid artery gunshot injury

A 9-year-old boy was accidentally shot at close range with a pistol. The bullet entered through the left anterior neck and severed the left common carotid artery. Emergency surgery was performed with an end-to-end anastomosis. He recovered gradually from severe right-sided hemiparesis. CT scans demonstrated left parietal infarction. Within months he developed right hemidystonia, which progressed over the next few years. The movement disorder was refractory to medical therapy. MR scans showed a large demarcated defect in the left parietal lobe extending to the occipital lobe, to the insula and to the posterior ventral putamen. At age 18 the patient underwent a staged left-sided thalamotomy. The hemidystonia improved postoperatively but later partially recurred Received: 8 October 1996     

The role of the parietal lobe in visual extinction studied with transcranial magnetic stimulation

Interhemispheric competition between homologous areas in the human brain is believed to be involved in a wide variety of human behaviors from motor activity to visual perception and particularly attention. For example, patients with lesions in the posterior parietal cortex are unable to selectively track objects in the contralesional side of visual space when targets are simultaneously present in the ipsilesional visual field, a form of visual extinction. Visual extinction may arise due to an imbalance in the normal interhemispheric competition. To directly assess the issue of reciprocal inhibition, we used fMRI to localize those brain regions active during attention-based visual tracking and then applied low-frequency repetitive transcranial magnetic stimulation over identified areas in the left and right intraparietal sulcus to asses the behavioral effects on visual tracking. We induced a severe impairment in visual tracking that was selective for conditions of simultaneous tracking in both visual fields. Our data show that the parietal lobe is essential for visual tracking and that the two hemispheres compete for attentional resources during tracking. Our results provide a neuronal basis for visual extinction in patients with parietal lobe damage.     

A severe frontal-parietal lobe syndrome following cerebellar damage.

We report a case study of a frontal and parietal lobe syndrome with memory loss after unilateral left-sided cerebellar damage caused by a stroke in a patient with right cerebellar unusual developmental agenesis. The syndrome consisted of severe deficits in planning an organized sequence of events, in visuo-constructive abilities and inappropriate jocularity. These changes are ascribed in part to cerebellar-pontine lesions with resulting frontal lobe diaschisis as documented by single-photon emission computed tomography in the absence of morphological damage to the neocortex.