Neurological research
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Neurological research · Jan 2001
Case ReportsMagnetoencephalographic investigation of somatosensory homunculus in patients with peri-Rolandic tumors.
In order to investigate functional topography of the hand somatosensory cortex in five patients with peri-Rolandic tumors (four frontal lobes and one parietal lobe), we recorded somatosensory evoked fields (SEFs) using magnetoencephalography (MEG) after stimulation of the median nerve (MN) and the five digits. The results obtained were compared with those of five normal healthy subjects. In all five patients, SEFs following MN and digit stimulation showed the previously described respective N20m and N22m components of primary sensory response. ⋯ The cortical representations of the hand were identical to those of normal subjects, arranging in an orderly somatotopic way from lateral inferior to medial superior in the sequence thumb, MN, index, middle, ring, and little fingers. This sensory homunculus was confirmed by cortical recording of the somatosensory evoked potentials (SEPs) at the time of surgery. Thus, we demonstrate that SEFs, recorded on MEG in conjunction with source localization techniques, are useful to non-invasively investigate the functional topography of the human hand somatosensory cortex in pathological conditions.
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Neurological research · Jan 2001
The influence of ruptured cerebral aneurysm localization on the blood flow velocity evaluated by transcranial Doppler ultrasonography.
The relationship between changes of blood flow velocities in cerebral arteries measured by transcranial Doppler ultrasonography and aneurysm localization was investigated in a group of 165 patients after aneurysmal subarachnoid hemorrhage (SAH). Mean blood flow velocities (MFV) in the middle cerebral artery (MCA) and anterior cerebral artery (ACA) were registered. In patients with aneurysm of internal carotid artery and MCA (group A) statistically significant higher values of MFV from the 1st to the 5th day and on the 12th, 13th, 14th, 15th, and 19th day after SAH were found compared to patients with aneurysm of the anterior communicating artery, ACA, and pericallosal artery (group B). ⋯ MFV differences between group A and group B in 38 patients subjected to delayed surgery were not observed. The influence of aneurysm localization was observed between the 7th and 14th day after SAH. Critical MFV values for vasospasm in the MCA should be 120 cm sec-1 and in the ACA 90 cm sec-1.
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Neurological research · Jan 2001
Comparative StudyApproaches to the sellar and parasellar region: anatomic comparison of endonasal-transsphenoidal, sublabial-transsphenoidal, and transethmoidal approaches.
Various surgical approaches have been described for treating lesions which arise in the sellar region. The popular transnasal-transsphenoidal and transethmoidal-transsphenoidal approaches avoid the morbidity associated with transcranial operations while allowing enough exposure to successfully remove most lesions that arise in and around the sella. The goal of the present study was to accurately quantify the amount of exposure to the sellar and suprasellar region that the transethmoidal-transsphenoidal, endonasal-transphenoidal, and sublabial-transsphenoidal approaches provide. ⋯ It was found that the sublabial-transsphenoidal approach afforded the greatest volume of exposure superior and anterior to the dorsum sella. The endonasal-transsphenoidal and the transethmoidal approaches were both found to offer less suprasellar volume exposure, with the transethmoidal approach offering the least. The authors believe the information obtained through this study illustrates some important anatomical relationships which can be used to advantage by the surgeon to tailor the most appropriate approach, depending upon the precise location of the lesion either within the sella or suprasellar region.