Intraoperative neurophysiologic monitoring and neurologic outcomes in patients with epidural spine tumors

Purpose

Multimodal intraoperative neurophysiologic monitoring (IOM) provides assessment of spinal cord pathways during neurosurgery. Despite widespread use, few data exist regarding sensitivity and specificity of IOM in predicting neurologic outcome during decompression and instrumentation for epidural spine tumors.

Methods

Retrospective analysis evaluated consecutive spine procedures involving IOM modalities (somatosensory evoked potentials [SSEP], motor evoked potentials [MEP], and electromyography [(EMG]) from 2007 to 2009. Demographic and surgical information, intraoperative neurophysiologic data, and pre- and postoperative neurologic status were collected. All cases involved neoplastic epidural spinal cord compression by a primary or metastatic tumor and included posterolateral decompression and instrumented fusion.

Results

Two-hundred and eight consecutive patients had spine surgery during this time period and one hundred and fifty-two met inclusion criteria. All patients had SSEP monitoring, with 4 having transient changes and 7 persistent changes. One hundred and twenty-two patients had combined SSEP and MEP monitoring, with 3 having transient changes and 4 persistent changes in MEP signals. Two patients had neurophysiologic changes associated with hypotension and correction led to normalization. One developed new neurologic deficits after surgery. Two from the total cohort had new postoperative neurologic deficits. One had a transient decrease in MEP amplitude while the other had no intraoperative changes.

Discussion

These cases are often long with significant blood loss, and stability of multiple IOM modalities provides reassurance that spinal cord function remains intact. Signal changes should result in scrutiny of blood pressure, surgical technique and anesthesia. Preserved IOM signals are suggestive of preserved neurologic outcome.     

Parkinson's disease cybrids,differentiated or undifferentiated,maintain morphological and biochemical phenotypes different from those of control cybrids

SH‐SY5Y, control, and Parkinson's disease (PD) cybrids prepared from an Indian population were differentiated using retinoic acid (RA) for understanding their dopaminergic characteristics and neuritogenesis. Undifferentiated control and PD cybrids exhibited higher levels of TH mRNA, but lower c‐RET expression, short neurites, low neuritic density, and low proportion of cells with neurites compared with the undifferentiated parent cell line, SH‐SY5Y. The expression levels of DAT and Ptx3 were similar to SH‐SY5Y. PD cybrids showed poor viability and lower differentiating potency than SH‐SY5Y or control cybrids. RA treatment for 6 days elevated c‐RET expression and corrected the neuritic morphology of the control, but not of PD cybrids. Cell viability was found to be reduced in differentiated control and PD cybrids. TH expression level was significantly elevated in SH‐SY5Y following RA treatment, but not in both the cybrids. In differentiated control and PD cybrids, the TH immunofluorescence intensity was significantly lower compared with SH‐SY5Y cells. MitoTracker Green fluorescence intensity of the mitochondria was higher in differentiated PD cybrids. Dopamine released into the medium was unaffected in the differentiated SH‐SY5Y or in the control cybrids but was significantly elevated in PD cybrids. These results suggest that PD cybrids, differentiated or undifferentiated, maintained morphological and biochemical phenotypes significantly different from those of the control cybrids, or the differentiated SH‐SY5Y cells, and therefore could be an ideal cellular model of the disease for pharmacological screening of drugs and for investigation of the pathophysiology of PD. © 2013 Wiley Periodicals, Inc.     

Etiological spectrum of hypokalemic paralysis: A retrospective analysis of 29 patients

Background:

Hypokalemic paralysis is characterized by episodes of acute muscle weakness associated with hypokalemia. In this study, we evaluated the possible etiological factors in patients of hypokalemic paralysis.

Materials and Methods:

We reviewed the records of 29 patients who were admitted with a diagnosis of hypokalemic paralysis. Modified Guillain-Barre´ Syndrome disability scale was used to grade the disability.

Results:

In this study, 15 (51.7%) patients had secondary causes of hypokalemic paralysis and 14 patients (42.3%) had idiopathic hypokalemic paralysis. Thyrotoxicosis was present in six patients (20.6%), dengue infection in four patients (13.7%), distal renal tubular acidosis in three patients (10.3%), Gitelman syndrome in one patient (3.4%), and Conn''s syndrome in one patient (3.4%). Preceding history of fever and rapid recovery was seen in dengue infection-induced hypokalemic paralysis. Approximately 62% patients had elevated serum creatinine phosphokinase. All patients had recovered completely following potassium supplementation. Patients with secondary causes were older in age, had significantly more disability, lower serum potassium levels, and took longer time to recover.

Conclusion:

In conclusion, more than half of patients had secondary causes responsible for hypokalemic paralysis. Dengue virus infection was the second leading cause of hypokalemic paralysis, after thyrotoxicosis. Presence of severe disability, severe hypokalemia, and a late disease onset suggested secondary hypokalemic paralysis.     

Quick screening of cognitive function in Indian multiple sclerosis patients using Montreal cognitive assessment test-short version

Background:

Cognitive impairments in multiple sclerosis (MS) are now well recognized worldwide, but unfortunately this domain has been less explored in India due to many undermining factors. The aim of this study was to evaluate cognitive impairments in Indian MS patients with visual or upper limb motor problems with the help of short version of Montreal cognitive assessment test (MoCA).

Subjects and Methods:

Thirty MS patients and 50 matched controls were recruited for the 12 points MoCA task. Receiver operating characteristic curve (ROC) analysis was performed to determine optimal sensitivity and specificity of the 12 points MoCA in differentiating cognitively impaired patients and controls.

Results:

The mean 12 points MoCA scores of the controls and MS patients were 11.56 ± 0.67 and 8.06 ± 1.99, respectively. In our study, the optimal cut-off value for 12 points MoCA to be able to differentiate patients with cognitive impairments from controls is 10/12. Accordingly, 73.3% patients fell below the cut off value. Both the groups did not have significant statistical differences with regard to age and educational years.

Conclusion:

The 12 points, short version of MoCA, is a useful brief screening tool for quick and early detection of mild cognitive impairments in subjects with MS. It can be administered to patients having visual and motor problems. It is of potential use by primary care physicians, nurses, and other allied health professionals who need a quick screening test. No formal training for administration is required. Financial and time constraints should not limit the use of the proposed instrument.Key Words: Cognitive impairments, Indian, montreal cognitive assessment test, multiple sclerosis     

Low luminance/eyes closed and monochromatic stimulations reduce variability of flash visual evoked potential latency

Context:

Visual evoked potentials are useful in investigating the physiology and pathophysiology of the human visual system. Flash visual evoked potential (FVEP), though technically easier, has less clinical utility because it shows great variations in both latency and amplitude for normal subjects.

Aim:

To study the effect of eye closure, low luminance, and monochromatic stimulation on the variability of FVEPs.

Subjects and Methods:

Subjects in self-reported good health in the age group of 18-30 years were divided into three groups. All participants underwent FVEP recording with eyes open and with white light at 0.6 J luminance (standard technique). Next recording was done in group 1 with closed eyes, group 2 with 1.2 and 20 J luminance, and group 3 with red and blue lights, while keeping all the other parameters constant. Two trials were given for each eye, for each technique. The same procedure was repeated at the same clock time on the following day.

Statistical Analysis:

Variation in FVEP latencies between the individuals (interindividual variability) and the variations within the same individual for four trials (intraindividual variability) were assessed using coefficient of variance (COV). The technique with lower COV was considered the better method.

Results:

Recording done with closed eyes, 0.6 J luminance, and monochromatic light (blue > red) showed lower interindividual and intraindividual variability in P2 and N2 as compared to standard techniques.

Conclusions:

Low luminance flash stimulations and monochromatic light will reduce FVEP latency variability and may be clinically useful modifications of FVEP recording technique.Key Words: Eye closure, flash visual evoked potentials, latency variability, luminance, monochromatic light, visual evoked potentials     

Clot composition and treatment approach to acute ischemic stroke: The road so far

Recent histological studies of thrombi retrieved from patients with an acute ischemic stroke using the endovascular thrombectomy devices and correlation with early vessel computed tomography (CT) and magnetic resonance imaging (MRI) characteristics have given relevant insights into the pathophysiology of thrombotic lesions and may facilitate the development of improved reperfusion treatment approaches. We present a review of recent studies on the histopathologic analysis of thrombi, studies of MRI, and CT imaging correlation with thrombus histology, and detailed structural analysis of thromboemboli retrieved by thrombectomy devices during an acute ischemic stroke.Key Words: Clot composition, histopathology, stroke, thrombus     

Technology-aided leisure and communication opportunities for two post-coma persons emerged from a minimally conscious state and affected by multiple disabilities

This study assessed technology-aided programs for helping two post-coma persons, who had emerged from a minimally conscious state and were affected by multiple disabilities, to (a) engage with leisure stimuli and request caregiver's procedures, (b) send out and listen to text messages for communication with distant partners, and (c) combine leisure engagement and procedure requests with text messaging within the same sessions. The program for leisure engagement and procedure requests relied on the use of a portable computer with commercial software, and a microswitch for the participants’ response. The program for text messaging communication involved the use of a portable computer, a GSM modem, a microswitch for the participants’ response, and specifically developed software. Results indicated that the participants were successful at each of the three stages of the study, thus providing relevant evidence concerning performance achievements only minimally documented. The implications of the findings in terms of technology and practical opportunities for post-coma persons with multiple disabilities are discussed.