Electrophysiologic evaluation of intermittent sacral nerve dysfunction in lumbar spinal canal stenosis

Cerebrospinal fluid signal loss sign: assessment of a new radiological sign in lumbar spinal stenosis

PURPOSE

Sedimentation sign was reported to have high sensitivity and specificity for diagnosis of lumbar spinal stenosis (LSS). We aimed to determine cerebrospinal fluid signal loss (CSFSL) at the intervertebral disc levels in the sagittal plane using a numerical scoring system and to evaluate the diagnostic value of this method in differential diagnosis of LSS and non-specific low back pain (LBP) and compare it with SS.

MATERIALS AND METHODS

We included consecutive patients between 50 and 80 years old, with lumbar spinal MRI examination in our institution. These patients were divided into two groups as LSS and LBP, according to symptoms and radiological findings. CSFSL sign was evaluated for both groups by two radiologists independently, using MR images. Sensitivity and specificity of both signs were calculated.

RESULTS

A total of 406 patients (98 LSS and 308 non-specific LBP) were included. SS and CSFSL sign had a sensitivity of 90.8% and 82.7% and specificity of 75.4% and 84.1% in the whole cohort, respectively. When patients were grouped by dural sac cross-sectional areas (CSA), sensitivity and specificity of SS were 100% and 4.4%, 87.5% and 31.8%, and 41.7% and 76%, respectively, and sensitivity and specificity of CSFSL sign were 95.7% and 11.1%, 75% and 77.3%, and 16.7 and 92% for severe (CSA < 80 mm2), moderate (CSA: 80-100 mm2), mild (CSA: 100-120 mm2) radiologic stenosis, respectively. In moderate stenosis, accuracies of SS and CSFSL sign were 76.3% and 55.3%, respectively.

CONCLUSION

CSFSL sign might be used to distinguish LSS from LBP and unlike SS it is successful in moderate stenosis.

Priapism, a symptom of claudication of the cauda equina in spinal stenosis

Priapism is defined as a persistent penile erection in the absence of sexual arousal. This symptom has been documented in patients with spinal stenosis although it is considered a rare finding. The European Association of Urology guidelines on priapism [Salonia et al., 2014] list cauda equina syndrome and spinal stenosis as causative factors for ischemic priapism although the literature describing this phenomenon appears sparse. Priapism can be a rare symptom of lumbar spine stenosis/transient cauda equina compression. This presentation is complex and believed to be a parasympathetic mediated autonomic disorder. This article discusses the relationship between spinal stenosis, cauda equina syndrome and priapism using available literature. Greater awareness of this clinical finding may help clinicians in their clinical decision making. In patients with suspected cauda equina syndrome, subjective enquiry regarding the symptom priapism may add to the patients overall clinical picture.

Isolated intermittent neurogenic priapism: an unusual presentation in degenerative lumbar spinal stenosis

Priapism is a relatively uncommon clinical presentation. The well-recognised causes are sickle cell anaemia and the use of medications, such as vasoactive erectile agents. Infrequently, it could be the result of lumbar spinal stenosis. The authors reported an elderly man with 1-year history of isolated intermittent priapism aggravated by walking. MRI showed lumbosacral spondylosis with severe stenosis at the level of L4-L5. Total laminectomy of L4 and L5 was done, resulting in a rapid and complete resolution of symptom without recurrence during the follow-up time of 10 years.

Guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 15: electrophysiological monitoring and lumbar fusion

Based on the medical evidence provided by the literature reviewed, there does not appear to be support for the hypothesis that any form of intraoperative monitoring improves patient outcomes following lumbar decompression or fusion procedures for degenerative spinal disease. Evidence does indicate that a normal evoked EMG response is predictive for intrapedicular screw placement (high NPV for breakout). The presence of an abnormal EMG response does not, however, exclude intrapedicular screw placement (low PPV). The majority of clinically apparent postoperative nerve injuries are associated with intraoperative changes in SSEP and/or DSEP monitoring. For this reason, changes in DSEP/SSEP monitoring appear to be sensitive to nerve root injury. There is a high-false positive rate, however, and changes in DSEP and SSEP recordings are frequently not related to nerve injury. A normal study has been shown to correlate with the lack of a significant postoperative nerve injury. There is no substantial evidence to indicate that the use of intraoperative monitoring of any kind provides useful information to the surgeon in terms of assessing the adequacy of nerve root decompression at the time of surgery.

Electrophysiology of radiculopathies

The anatomy, pathophysiology, and clinical evaluation of radiculopathies are discussed. Defining whether root injury is present and which roots are involved can be difficult but critical for patient management. In conjunction with clinical and radiological information, studies that establish physiological abnormalities of roots should be helpful and important. Clinical neurophysiological studies for radiculopathies are performed frequently but have yet to achieve a universally accepted role in the evaluation of these patients. Electrophysiological techniques for the evaluation of radiculopathies are reviewed. Needle electromyography is the best established of these procedures but has the disadvantage of requiring injury to motor fibers of both a certain degree and distribution. Nerve conduction studies may rarely be abnormal in radiculopathies but are needed to be certain other conditions that may produce similar symptoms and signs are not present. H reflexes and F waves probably have roles in the evaluation of radiculopathies but published reports about F waves in radiculopathies have been marred by inadequate methodology. There is evidence based on large series of patients that somatosensory evoked potentials can be helpful for evaluating patients with multilevel injury such as spinal stenosis, patients where electrophysiological studies may have their greatest clinical utility. Further work using either electrical stimulation with needles or magnetic stimulation of roots seems warranted. The demonstration of meaningful electrophysiological changes with activities that reproduce radicular symptoms may be a promising experimental approach. Available information does not necessarily answer critical questions about the role of electrophysiology in patients with radiculopathies. This cannot be done using analyses based on current ideas about evidence based medicine given the absence of a 'gold standard' for defining radiculopathies as well the absence of blinded studies. The available information provides strong arguments for further investigations evaluating different clinical neurophysiological techniques in the same patient, and for evaluating the value of these techniques by concentrating on their clinical import.

Decompressive surgery for typical lumbar spinal stenosis

Between 1991 and 1992, 103 consecutive patients (average age, 65 years) underwent decompressive surgery for treatment of typical lumbar spinal stenosis. Clinical results at 1-year followup revealed that four patients had revision surgery. At 2- to 5-years followup, there were no additional revision surgeries. Two patients underwent revision surgery for a deep infection, and two underwent revision surgery for a superficial infection. Outcome results showed that 77 patients completed the questionnaire, 15 were lost to followup and 11 died. Postoperative results showed that 64 of 77 patients had no or mild pain, 72 of 77 patients stated that they were satisfied or somewhat satisfied with their overall results of surgery, and 73 of 77 were satisfied with pain relief. Younger patients had greater improvement in function and a greater reduction in severity scores. However, satisfaction was similar in both groups. Survivorship results (failure was revision surgery) showed at the end of 4 years, a patient had a 95% chance of not having revision surgery. Statistically, there was no association between outcome and cofactors such as scoliosis, spondylolisthesis, number of levels decompressed, discectomy, or smoking. Satisfaction rates for older patients were similar to patients younger than 65 years although physical function scores and severity scores were less.

Spinal cord monitoring: current state of the art

The intraoperative application of evoked potential and electromyographic (EMG) monitoring has increased significantly over the last 2 decades. Cranial nerve monitoring is widely accepted and used by otologists, neurologic surgeons, and ophthalmologists. Direct and indirect techniques for assessing the peripheral nervous system are used by plastic and orthopedic surgeons when performing intraoperative nerve grafting. Myriad techniques and applications for monitoring the spinal cord and peripheral nervous system have been developed, evaluated, and used by orthopedic and neurologic surgeons involved in spinal surgery.

Recruitment curve of the soleus H reflex in patients with neurogenic claudication

The diagnosis of neurogenic claudication (NC) remains uncertain when no definite signs of radicular lesions are found in electrophysiological testing. However, the functional deficit could be demonstrated during the brief time in which the patients complain of pain and weakness in the muscles of the lower limbs after walking. We have used electrophysiological testing of the H reflex and the F wave to document the transient functional derangement expected to occur at the radicular level in patients with NC after walking. We examined the recruitment curve of the soleus H reflex, and the chronodispersion of the posterior tibial nerve F wave, at rest and after a walking exercise that triggered their symptoms in 10 patients with NC, with no positive electrophysiological findings of radicular lesion. The same studies were performed in 5 age-matched healthy volunteers, used as control subjects, who were asked to walk for 30 min. At rest before walking, no abnormalities were found in any of the patients. After walking, the H wave showed a transient increase in its threshold with respect to that of the M wave in 7 patients (70%). Such abnormality lasted for a mean period of 7 min. In 2 of these patients there was also an increase in the F-wave chronodispersion. Our data suggest that nerve conduction is transiently blocked in large myelinated fibers at a radicular level in patients with NC after walking. Partial interruption of the H-reflex circuit could be one of the pathophysiological mechanisms underlying NC.

Lumbar spinal stenosis causing intermittent priapism

The current report concerns the unusual symptom of intermittent priapism, or what may be termed 'involuntary penile erection', associated with proven degenerative lumbar spinal stenosis. Seven patients who were treated for intermittent claudication and spontaneous priapism during walking were studied in terms of clinical presentation, imaging findings, and some electrophysiological testing. Varying degrees of walking and standing tolerance with these unusual symptoms appeared to be correlated with cauda equina constriction as was seen by radiological imaging. Although not statistically valid, external urethral sphincter evoked electromyography suggested the possibility of monitoring the unusual symptom during walking. Surgical spinal decompression is recommended to alleviate this symptom and the claudication.