Neurologia medico-chirurgica
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Neurol. Med. Chir. (Tokyo) · Aug 2017
Observational StudyEfficacy of Fiber Tractography in the Stereotactic Surgery of the Thalamus for Patients with Essential Tremor.
Several targets and targeting methods are utilized in stereotactic surgery to achieve tremor suppression for patients with intractable tremor. Recent developments in magnetic resonance imaging, including diffusion tensor imaging, have enabled the setting of appropriate targets in stereotactic surgery. In this retrospective study, the optimal target to suppress tremors in stereotactic surgery was explored using diffusion tensor image-based fiber tractography. ⋯ Twelve lesions in thalamotomy patients or active contacts of the lead in thalamic stimulation patients were on the cerebello-thalamo-premotor cortical fiber tract (12/14 lesions or active contacts: 86%). In conclusion, the cerebello-thalamo-premotor cortical fiber tract may be an optimal target for tremor suppression. Diffusion tensor image-based fiber tractography may enable us to both determine the optimal target to achieve strong tremor suppression and to reduce the number of adverse events by keeping lesions or electrodes away from important fiber tracts, such as the pyramidal tract and spinothalamic fibers.
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Neurol. Med. Chir. (Tokyo) · May 2017
ReviewDisorder of Executive Function of the Brain after Head Injury and Mild Traumatic Brain Injury - Neuroimaging and Diagnostic Criteria for Implementation of Administrative Support in Japan.
The diagnotic criteria for disorder of the executive function of the brain (DEFB) as a syndrome of sequela were administratively established (ad-DEFB) in Japan in 2006 to support disabled patients whose impairment, limited to cognition (memory, attention, execution, and behavior), emerges after organic brain injuries regardless of physical deficits. However, some patients suffering from traumatic brain injury (TBI) have been excluded from receiving medico-social services. ⋯ Recent development of new MRI neuroimaging modalities and positron emission tomography (PET) imaging makes it possible to detect regions of minute organic lesions and metabolic dysfunction in the brain where organic lesions may be absent or cannot be detected on conventional CT or MRI. In this review, we discuss diagnostic criteria for mild TBI and ad-DEFB, the relationship between the two disorders, characteristic neuroimaging [(MRI and 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET)] of diffuse brain injury including cerebral concussion, which is the principal cause of mild TBI, and suggested pathological mechanisms of ad-DEFB in DBI.
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Neurol. Med. Chir. (Tokyo) · Dec 2016
Histopathological Findings in Brains of Patients Who Died in the Acute Stage of Poor-grade Subarachnoid Hemorrhage.
Patients with poor-grade aneurysmal subarachnoid hemorrhage (SAH) are likely to die due to irreversible acute-stage primary brain damage. However, the mechanism(s) and pathology responsible for their high mortality rate remain unclear. We report our findings on the brains of individuals who died in the acute stage of SAH. ⋯ Edema and congestion were more obvious in areas where the subarachnoid clot tightly adhered to the pia mater. Pathologically, the brains of deceased patients with acute poor-grade SAH were characterized by edema and multifocal infarcts spread throughout the whole brain; they were thought to be attributable to venous ischemia. Diffuse disturbance in venous drainage attributable to an abrupt increase in the intracranial pressure and focal disturbances due to tight adhesion of the subarachnoid clot to the pia mater, may contribute strongly to irreversible brain damage in the acute stage of SAH.
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Developmental venous anomalies (DVAs), previously called venous angiomas, are the most frequently encountered cerebral vascular malformations. However, DVA is considered to be rather an extreme developmental anatomical variation of medullary veins than true malformation. DVAs are composed of dilated medullary veins converging centripetally into a large collecting venous system that drains into the superficial or deep venous system. ⋯ These phenomena are considered to be the result of venous hypertension associated with DVAs. With the advance of diagnostic imagings, perfusion study supports this hypothesis demonstrating that some DVAs have venous congestion pattern. Although DVAs should be considered benign and clinically silent, they can have potential venous hypertension and can be vulnerable to hemodynamic changes.
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Neurol. Med. Chir. (Tokyo) · Aug 2016
ReviewBasic Principles and Recent Trends of Transcranial Motor Evoked Potentials in Intraoperative Neurophysiologic Monitoring.
Transcranial motor evoked potentials (TcMEPs), which are muscle action potentials elicited by transcranial brain stimulation, have been the most popular method for the last decade to monitor the functional integrity of the motor system during surgery. It was originally difficult to record reliable and reproducible potentials under general anesthesia, especially when inhalation-based anesthetic agents that suppressed the firing of anterior horn neurons were used. Advances in anesthesia, including the introduction of intravenous anesthetic agents, and progress in stimulation techniques, including the use of pulse trains, improved the reliability and reproducibility of TcMEP responses. ⋯ Additionally, false negative cases have been occasionally encountered. Recently, several facilitative techniques using central or peripheral stimuli, preceding transcranial electrical stimulation, have been employed to achieve sufficient depolarization of motor neurons and augment TcMEP responses. These techniques might have potentials to improve the reliability of intraoperative motor pathway monitoring using TcMEPs.