Bedside electromyography for clinical assessment of sacral motor and reflex activity adapted for patients hospitalized with acute neurological conditions: a pilot study

STUDY DESIGN

Pilot cohort study.

OBJECTIVE

To develop and implement a sacral electromyographic (sEMG) technique at bedside to ascertain sparing of sacral motor activity and reflexes in patients hospitalized for acute neurological conditions.

SETTING

Hôpital du Sacré-Coeur de Montréal a Canadian Level-1 university trauma center specialized in SCI care.

METHODS

Nine patients underwent digital rectal examination (DRE) and sEMG, assessing voluntary anal contraction and sacral spinal reflexes (bulbocavernosus reflex and the anal wink). Our sEMG technique utilized surface recording electrodes and tactile elicitation of reflexes. EMG signal was acquired at bedside through the Noraxon MR3 system.

RESULTS

It was quick, well accepted and did no harm. We found that contrary to the DRE, sEMG detected subclinical sacral motor activity and reflexes in 20% of cases for voluntary anal contraction and 40% of cases for the anal wink.

CONCLUSION

We believe our sEMG technique is a powerful tool able to enhance management of patients suffering from acute neurological impairments and requiring sacral function assessment.

Neurophysiological Effects of Electrical Stimulation on a Patient with Neurogenic Bowel Dysfunction and Cauda Equina Syndrome after Spinal Anesthesia: A Case Report

Neurogenic bowel dysfunction (NBD) is common in patients with cauda equina syndrome (CES). Previous studies have reported that electrical stimulation (ES) improves NBD but more neurophysiologic evidence is required. This case report describes a patient who experienced difficulty with defecation as a result of cauda equina syndrome (CES) that developed after a cesarean section performed 12 years ago under spinal anesthesia. The neurophysiological effects were assessed using the bulbocavernosus reflex (BCR) and electromyography (EMG). Two ES treatments, interferential current therapy and transcutaneous electrical stimulation, were used to stimulate the intestine and the external anal sphincter, respectively. The BCR results showed right-side delayed latency and no response on the left side. Needle EMG revealed abnormal spontaneous activities of the bilateral bulbocavernosus (BC) muscles. Electrodiagnostic testing revealed chronic bilateral sacral polyradiculopathy, compatible with CES. After treatment, the patient reported an improved perianal sensation, less strain and time for defecation than before, and satisfaction with her bowel condition. At the follow-up electrodiagnosis, the BCR latency was normal on the right side—needle EMG revealed reductions in the abnormal spontaneous activities of both BC muscles and re-innervation of the right BC muscle. Electrodiagnostic testing can offer insight into the neurophysiological effects of ES, which can help in understanding the mechanism of action and optimizing the therapy for patients with NBD.

Neurophysiology of the pelvic floor in clinical practice: a systematic literature review

Neurophysiological testing of the pelvic floor is recognized as an essential tool to identify pathophysiological mechanisms of pelvic floor disorders, support clinical diagnosis, and aid in therapeutic decisions. Nevertheless, the diagnostic value of these tests in specific neurological diseases of the pelvic floor is not completely clarified. Seeking to fill this gap, the members of the Neurophysiology of the Pelvic Floor Study Group of the Italian Clinical Neurophysiology Society performed a systematic review of the literature to gather available evidence for and against the utility of neurophysiological tests. Our findings confirm the utility of some tests in specific clinical conditions [e.g. concentric needle electromyography, evaluation of sacral reflexes and of pudendal somatosensory evoked potentials (pSEPs) in cauda equina and conus medullaris lesions, and evaluation of pSEPs and perineal sympathetic skin response in spinal cord lesions], and support their use in clinical practice. Other tests, particularly those not currently supported by high-level evidence, when employed in individual patients, should be evaluated in the overall clinical context, or otherwise used for research purposes.

Lower urinary tract dysfunction in patients with peripheral nervous system lesions

The prevalence of lower urinary tract (LUT) dysfunction in peripheral nervous system (PNS) disorders is larger than in comparable control populations. This is particularly true for polyneuropathies with autonomic nervous system involvement, and for localized lesions with LUT innervation. LUT symptoms may be the guide to the diagnosis of processes localized in the lumbosacral spinal canal (as in cauda equina syndrome), and in the pelvis. Typical LUT dysfunctions (LUTD) caused by PNS involvement include bladder and sphincter hypoactivity with poor emptying, and incontinence. Paradoxically, bladder overactivity may also occur in pure PNS lesions. The acute cauda equina syndrome is an emergency requiring magnetic resonance imaging and surgery; in chronic neurogenic LUTD due to PNS involvement, the diagnosis of the lesion may be clarified by clinical neurophysiologic testing. Other important causes of neurogenic LUT dysfunction are perineoabdominal and pelvic surgeries. Surgeons are devising nerve-sparing techniques to prevent such major and often persistent complications in patients who are otherwise cured of the underlying disease. LUTD significantly affects the quality of life in patients and may lead to recurring urinary infections and upper urinary tract involvement. Thorough assessment of LUT function by urodynamics may be necessary in patients who are not improved by simple conservative measures.

Contribution of sacral neuromodulation to manage persistent voiding dysfunction after surgery for deep infiltrating endometriosis with colorectal involvement: preliminary results

OBJECTIVE

Around 5% of women experience persistent voiding dysfunction after surgery for deep infiltrating endometriosis (DIE) with colorectal involvement. The gold standard to manage persistent voiding dysfunction is intermittent self-catherization, but this treatment may reduce quality of life of the patients due to care constraints. The objective of our study was to assess the contribution of sacral neuromodulation (SNM) in the management of persistent voiding dysfunction secondary to surgery for DIE with colorectal resection.

STUDY DESIGN

Five patients referred for persistent voiding dysfunction after surgery for DIE with colorectal resection were included and fitted with a temporary SNM system to test for feasibility. This consisted of placing an electrode unilaterally next to the S3 sacral nerve root and connecting it to an external pacemaker. The patients wore the electrode and the external neurostimulator for 21 days and kept a voiding diary. The SNM test was considered positive when a 50% decrease in self-catheterization was achieved after removal of the electrode. The system was implanted permanently in patients with a positive SNM test. Urodynamic tests were performed before and after the SNM test.

RESULTS

Two of the five patients had a positive SNM test and were implanted permanently. At 40 months the first patient had completely stopped self-catheterization and the second patient was performing self-catheterization twice a day with a post voiding residue volume of less than 100ml at 52 months.

CONCLUSION

SNM could be a curative technique in some patients with persistent voiding dysfunction after surgery for DIE. Further studies are required to better select patients who might benefit from SNM testing and subsequent device implantation.

Electrophysiological study of the bulbocavernosus reflex: normative data

In the clinical setting the bulbocavernosus reflex (BCR) is elicited by squeezing the glans penis and digitally palpating the contraction of the bulbocavernosus (BC) muscle. In neurophysiology the BCR is obtained by stimulating the dorsal nerve of the penis or clitoris and by recording the response from BC muscle and it should be performed in selected patients with suspected urinary, bowel, or sexual neurogenic dysfunction. The BCR is considered one of the sacral neurophysiological tests of the greatest clinical utility. Previous normative data were obtained on small samples. The aim of this study was to determine normative values for the BCR in a large sample of men. We studied a large population (105 men; mean age 53 years, range 19-73 years) without central or peripheral neurological diseases. In each subject the sacral reflex was elicited by electrical stimulation of the base of the dorsum penis and recorded using a surface electrode from the BC muscle. We recorded the latency, calculated at onset, and the maximal amplitude of response, calculated peak to peak. We were able to detect the BCR in all the men. No correlation between BCR latency and age was found (r=0.136; p=0.160). The mean onset latency value was 33.0±4.85 ms (mean±2SD, range 26.8-39.4). The mean amplitude value was 16.53±12.21 μV (mean±2SD, range 4.2-43.6). Our normative data on the BCR were similar to previously published data.

Sacral neurophysiologic study in patients with chronic spinal cord injury

AIMS

Neurophysiologic testing of the sacral reflex has demonstrated utility in the diagnosis of sacral lower motor neuron lesions. The aim of the present study was to also apply this test to patients with upper motor neuron lesions.

METHODS

A group of 16 male patients with chronic suprasacral spinal cord lesions was prospectively recruited. In addition to history and clinical neurologic examination (including anal sphincter tone, saddle sensation, and penilo-cavernosus reflex testing), sacral neurophysiologic studies were performed. Neurophysiologic testing included quantitative electromyography of the external anal sphincter (motor unit potential (MUP) count during relaxation and MUP analysis), and neurophysiologic measurement of the penilo-cavernosus reflex (elicitation threshold and latency) on electrical stimulation. The findings were compared to data obtained in the control group of 26 men.

RESULTS

Clinical elicitability of the penilo-cavernosus reflex was increased, and the neurophysiologically measured reflex threshold reduced in patients (<0.02). No significant differences were found in clinical assessment of anal sphincter tone, MUP count, reflex latency, and quantitative MUP analysis. The diagnostic sensitivity of individual parameters was low (≤25%).

CONCLUSIONS

In patients with chronic spinal cord injury, increased elicitability of the penilo-cavernosus reflex was found. However, none of the assessed neurophysiologic parameters was found to assist in the diagnosis of the sacral upper motor neuron lesion in individual patients. The shortened sacral reflex latency found in individual patients is therefore not a consequence of a suprasegmental lesion, but rather of the low position of the conus medullaris (e.g., in tethered cord syndrome).