1/9. Pseudodystonic hand posturing contralateral to a metastasis of the parietal association cortex.A 56 year-old patient, with a history of surgically removed breast cancer three years earlier, presented with incoordination of hand movements while playing piano. Neurological examination disclosed mild position sensory loss and limb-kinetic apraxia of the distal part of the right upper extremity. The most conspicuous neurological sign was a dystonic posturing of the right hand, which was only elicited when the patient outstretched her arms with the eyes closed. MRI revealed a metastatic lesion involving the left parietal cortex. The association of focal dystonic postures with lesions of the parietal association cortex indicates that dystonia may feature damage of brain cortical areas far from the basal ganglia. In addition, this provides support to the hypothesis that impairment of sensory pathways may play a role in the origin of some hyperkinetic movement disorders, such as dystonia and athetosis.- - - - - - - - - - ranking = 1keywords = cortex (Clic here for more details about this article) |
2/9. Somatosensory and skin temperature disturbances caused by infarction of the postcentral gyrus: a case report.Somatosensory functions are subdivided into 2 large groups: the elementary somatosensory functions, which consist of light touch, pain, thermal sensation, joint position sense, and vibration sense, and the intermediate somatosensory functions, which include 2-point discrimination, tactile localization, weight, texture, and shape perception. In this report, we describe a patient with somatosensory dysfunction after infarction of the postcentral gyrus. On physical examination a month after the onset of the infarction, voluntary movements were skillful, and both the elementary and intermediate somatosensory functions were disturbed in the right hand. The patient also displayed a decrease in the skin temperature of the right hand. The sensory-evoked potential in response to electrical stimulation of the right median nerve was normal, and brain MRI showed that the infarction was located in the posterior half of the left postcentral gyrus. These findings suggested that the lesion was situated at areas 1 and 2, and that area 3b was preserved. thermography revealed that the skin temperature of the right hand was decreased predominantly on the ulnar side, and that recovery from cooling with ice water was delayed. By comparing the results of our patient with a case report that showed no disturbance of the elementary somatosensory functions with a localized lesion in the postcentral gyrus, we suggest that area 1 participates in the elementary somatosensory functions and that skin temperature may be controlled somatotopically in the somatosensory cortex.- - - - - - - - - - ranking = 0.16666666666667keywords = cortex (Clic here for more details about this article) |
3/9. motor cortex stimulation in a patient with intractable complex regional pain syndrome type II with hemibody involvement. Case report.The authors describe the effectiveness of motor cortex stimulation (MCS) in a patient with complex regional pain syndrome (CRPS) Type II, formerly known as causalgia, with hemibody allodynia. During MCS, a subjective sensation of warm paresthesia developed in the painful hand and forearm and spread toward the trunk. pain and allodynia in the areas associated with this sensation were alleviated significantly. The analgesic effect of stimulation proved to be long lasting and was still present at the 12-month follow up. The authors speculate that MCS might exert its effect through the modulation of thalamic activity in this particular case of CRPS with hemisensory deficit. A central mechanism associated with functional disturbance in noxious-event processing in the thalamus might have an important role in the pathogenesis of the condition.- - - - - - - - - - ranking = 0.83333333333333keywords = cortex (Clic here for more details about this article) |
4/9. Motor excitability in a patient with a somatosensory cortex lesion.OBJECTIVE: We report a patient with an ischemic lesion in right somatosensory cortex who developed dystonic posturing and pseudo-athetotic involuntary left-sided finger movements during voluntary muscle contractions. methods: Motor excitability was assessed using transcranial magnetic stimulation techniques and electrical peripheral nerve stimulation. Results obtained from abductor digiti minimi muscles of both hands were compared. RESULTS: On the affected side, silent period duration and intracortical inhibition were reduced, indicating a loss of inhibitory properties. Intracortical facilitation was enhanced. Stimulus-response curves showed a smaller increase of motor evoked potential amplitudes when recorded during muscle relaxation, but not during voluntary muscle activation. CONCLUSIONS: The results suggest that, under normal conditions, somatosensory cortex modifies inhibitory as well as excitatory properties in the motor system.- - - - - - - - - - ranking = 1keywords = cortex (Clic here for more details about this article) |
5/9. A cognitive neuropsychological and psychophysiological investigation of a patient who exhibited an acute exacerbated behavioural response during innocuous somatosensory stimulation and movement.We report findings from a cognitive neuropsychological and psychophysiological investigation of a patient who displayed an exacerbated acute emotional expression during movement, innocuous, and aversive somatosensory stimulation. The condition developed in the context of non-specific white matter ischaemia along with abnormalities in the cortical white matter of the left anterior parietal lobe, and subcortical white matter of the left Sylvian cortex. Cognitive neuropsychological assessment revealed a pronounced deficiency in executive function, relative to IQ, memory, attention, language and visual processing. Compared to a normal control group, the patient [EQ] displayed a significantly elevated skin conductance level during both innocuous and aversive somatosensory stimulation. His pain tolerance was also significantly reduced. Despite this, EQ remained able to accurately describe the form of stimulation taking place, and to rate the levels of pain intensity and pain affect. These results suggest that EQ's exaggerated behavioural response and reduced pain tolerance to somatosensory stimulation may be linked to cognitive changes, possibly related to increased apprehension and fear, rather than altered pain intensity or pain affect per se.- - - - - - - - - - ranking = 0.16666666666667keywords = cortex (Clic here for more details about this article) |
6/9. Hot water epilepsy and focal malformation of the parietal cortex development.Hot water epilepsy (HWE) refers to a specific type of reflex epilepsy precipitated by the stimulus of bathing in hot water. HWE is considered to be a geographically specific epileptic syndrome since it mainly occurs in the Indian community. Spontaneous seizures may also occur later in life. The seizure pattern includes complex partial attacks. Although the pathogenesis of HWE is still unknown, temporal lobe has been thought to take part in the epileptogenesis. This paper reports on a 4-year-old girl who, at the age of 6 months, experienced complex partial seizures triggered by bathing in hot water. Non-provoked seizures intercritical EEG showed isolated spikes and spike-and-waves in the left parietal region. brain MRI detected a left parietal focal cortical dysplasia. This is the second patient with HWE in whom a cortical malformation has been observed. The observation present here and data reported in the literature seem to indicate that the sensory cortex might also be involved in triggering seizures precipitated by a bath in hot water. Moreover, the authors believe that MRI examination should be considered for this group of patients.- - - - - - - - - - ranking = 0.83333333333333keywords = cortex (Clic here for more details about this article) |
7/9. Illusory persistence of touch after right parietal damage: neural correlates of tactile awareness.We studied a patient who experienced 'palinaesthesia', an illusion of persistent touch following tactile stimulation on the left hand, subsequent to a right parietal meningioma affecting primary somatosensory regions in the postcentral gyrus (SI) and superior parietal gyrus (Brodmann area 7), but preserving the secondary somatosensory cortex (SII) in the upper lateral sulcus. This subjective sensation was accompanied by transient increases in objective measures of tactile threshold. The patient had mild deficits in superficial tactile perception, but showed severe left-sided extinction for offsets of tactile stimuli during bilateral stimulation, but not for onsets of stimuli. Functional MRI revealed increased neural activity during palinaesthesia selectively arising within the ipsilesional-right SI cortex, but no abnormality within left SI and bilateral SII. Right SI responded to the onset of new tactile stimuli on the left hand but not to their offset. By contrast, any tactile events on either hand modulated activity in contralateral SII regions, even undetected left-sided offsets. These data demonstrate that illusory persistence of touch following stimulation on the hand may result from sustained neural activity in a restricted region of the SI cortex outlasting the offset of the actual tactile stimuli. These findings also provide direct evidence for a critical role of SI in mediating conscious somatosensory experience on contralateral parts of the body.- - - - - - - - - - ranking = 0.5keywords = cortex (Clic here for more details about this article) |
8/9. Somatosensory activations during the observation of touch and a case of vision-touch synaesthesia.In this study, we describe a new form of synaesthesia in which visual perception of touch elicits conscious tactile experiences in the perceiver. We describe a female subject (C) for whom the observation of another person being touched is experienced as tactile stimulation on the equivalent part of C's own body. Apart from this clearly abnormal synesthetic experience, C is healthy and normal in every other way. In this study, we investigate whether C's 'mirrored touch' synesthetic experience is caused by overactivity in the neural system that responds to the observation of touch. A functional MRI experiment was designed to investigate the neural system involved in the perception of touch in a group of 12 non-synesthetic control subjects and in C. We investigated neural activity to the observation of touch to a human face or neck compared with the observation of touch to equivalent regions on an object. Furthermore, to investigate the somatosensory topography of the activations during observation of touch, we compared activations when observing a human face or neck being touched with activations when the subjects themselves were touched on their own face or neck. The results demonstrated that the somatosensory cortex was activated in the non-synesthetic subjects by the mere observation of touch and that this activation was somatotopically organized such that observation of touch to the face activated the head area of primary somatosensory cortex, whereas observation of touch to the neck did not. Moreover, in non-synesthetic subjects, the brain's mirror system-comprising premotor cortex, superior temporal sulcus and parietal cortex-was activated by the observation of touch to another human more than to an object. C's activation patterns differed in three ways from those of the non-synesthetic controls. First, activations in the somatosensory cortex were significantly higher in C when she observed touch. Secondly, an area in left premotor cortex was activated in C to a greater extent than in the non-synesthetic group. Thirdly, the anterior insula cortex bilaterally was activated in C, but there was no evidence of such activation in the non-synesthetic group. The results suggest that, in C, the mirror system for touch is overactive, above the threshold for conscious tactile perception.- - - - - - - - - - ranking = 1.1666666666667keywords = cortex (Clic here for more details about this article) |
9/9. Restricted pain and thermal sensory loss in a patient with pontine lacunar infarction: a clinical MRI study.Pure sensory syndrome (PSS) is characterized by hemisensory symptoms without other major neurological signs. It was initially attributed to thalamic lacunar infarction, but several reports have shown the PSS can be due to small infarcts involving the posterior part of the internal capsula, the cerebral cortex and the brainstem. Paramedian and lateral pontine infarctions are associated respectively with lemniscal and spinothalmic (ST) sensory impairment. We describe a patient with an isolated impairment of the ST modalities caused by a segmental paramedian pontine infarction.- - - - - - - - - - ranking = 0.16666666666667keywords = cortex (Clic here for more details about this article) |