Recording of motor and somatosensory evoked potential in an anaesthetised Wistar rat using digital polyrite system

Objectives: The aim of this article is to explain the detailed methodology to record Motor evoked potential (MEP) and somatosensory evoked potential (SSEP) in adult albino Wistar rat, male (200–250 g) which has not been defined previously. Materials and Methods: We have standardised recording of both MEP and SSEP in these rats under anaesthesia on ADI digital polyrite system. Results: Evoked potentials have been widely studied in spinal cord injured patients to estimate the degree of injury and to establish a predictive measure of functional recovery. MEPs and SSEPs, arising from the motor cortex or peripheral nerve and generated either by direct electrical stimulation or by transcranial magnetic stimulation, have been advocated as a reliable indicator of descending and ascending pathway integrity. In the rat brain, there is a physical overlap between the motor and somatosensory cortex. Hence, our objective was to identify the exact area for stimulation in the cortex where we could record maximum response with the application of minimum electrical stimulation. Conclusion: The recording of MEP and SSEP together provides a powerful neurological technique to monitor the tracts of the spinal cord.

Delayed Extensive White Matter Injury Caused by a Subdural Hemorrhage and Role of Corticospinal Tract Integrity

A subdural hemorrhage (SDH) is a common disorder with usually good prognosis. Most SDHs resolve with or without with minimal sequelae. We present a case report of a patient with SDH, who had delayed extensive white matter injury with disruptions of corticospinal tracts (CSTs) by diffusion tensor imaging (DTI) and showed abysmal prognosis, despite long-term rehabilitation. A 62-year-old man with an SDH underwent burr hole trephination for hematoma removal. Within 7 days, the hemorrhage diminished. At 12 weeks after the onset, the patient's weakness did not improve, and a follow-up magnetic resonance imaging revealed extensive leukomalacia, especially in the white matter. The DTI for CST revealed severe injury of CST integrity. He did not re-gain muscle strength and functional independence, despite 3 months of inpatient rehabilitation. This case describes SDH with delayed extensive white matter injury and exceptional poor prognosis and urges caution in that the SDH may induce very variable functional recovery. Besides, DTI for CST would be useful in predicting the long-term functional prognosis in extensive white matter injury.

Clinical study of magnetic resonance diffusion tensor tractography on the evaluation of prognosis in patients with cerebral infarction / 中国综合临床

Objective To investigate application of diffusion tensor tractography (DTT) on evaluating motor dysfunction degree of patients with cerebral infarction and explore the relationship between infracted focus and cortical spinal tract(CST).Methods Forty patients with cerebral infarctions in the different periods and 30 healthy volunteers were enrolled our study.They all underwent DTT check and then established CST.Meantime,all the patients were measured ADL score according to activities of daily living (ADL) on admission and two months after the onset.Results DTT image was made for both in patients and health control people.The CST was built in people in control group and its shape was like the adults'.Its shape was from the precentral gyrus down to internal capsule and continued to pontine and medulla oblongata.Each successive was form good consistency.The DTT image of patients' health side was like normal and injury corticospinal tract was affected by influence of infarction area at different level,manifested as loss of discontinuity and anatomical configuration consistency.Based on the degree of CST,there were 9 cases in grade Ⅰ,20 cases in grade Ⅱ and 11 cases at grade Ⅲ.DTT image showed that the damage level of CST had an negative relation with ADL score at 2 month after therapy (r =-0.914,P ＜ 0.05).Conclusion DTT can show the spatial positions of infarctions and CST at non-invasive lesion and analyze the influence of infarctions and corticospinal tract.Therefore,it can serve as the objective proof for judging the injury of the motor function and evaluating prognosis.

Prospective investigations on the secondary degeneration of corticospinal tracts in cervical spinal cord following a focal cerebral infarct with diffusion tensor imaging / 中国神经精神疾病杂志

Objective To investigate the secondary degeneration of corticospinal tracts in cervical spinal cord following a recently cerebral infarct with diffusion tensor imaging(DTI) and its potential impact on neurological recovery.Methods Twenty-six patients with a focal cerebral infract underwent DTI at the first week, the fourth and twelfth week after stroke onset, respectively.The NIH Stroke Scale (NIHSS), the Fugl-Meyer motor scale (FM) and the barthel index (BI) were used to evaluate the neurological function before every DTI.Twenty-six gender and age match healthy volunteers underwent DTI three times at same time points.The DTI parameters of mean diffusivity (MD) and fractional anisotropy (FA value) were measured at the cervical spinal cord and initial lesion.Results Compared to the controls, the FA values of the contralateral side corticospinal tracts in the cervical spinal cord in patients significantly decreased at every observed time point (P<0.01).In patients group, the FA values of the contralateral side corticospinal tracts in the cervical spinal cord decreased progressively from 1~(st) week to 12~(th) week (P<0.01), but MD remained unchange.The absolute value of the percent reduction of FA value of the contralateral side corticospinal tracts in the cervical spinal cord in patients associated negatively with the absolute value of the percent change of NIHSS and FM (P<0.05), but not with the absolute value of the percent change of BI(P>0.05).Conclusions Conclusions: The secondary degeneration of the corticospinal tracts resulted from cerebral infarction may extend to the cervical spinal cord.Which may last at lest three months and thus hamper the process of neurological recovery.