Sexual function in men with cauda equina lesions: a clinical and electromyographic study

OBJECTIVE: To investigate the effects of cauda equina lesions on sexual function in men. METHODS: Sexual function was investigated in 46 men with long standing cauda equina/conus medullaris lesions. All had clinical and radiological findings supporting the diagnosis. The validated Slovene translation of the international index of erectile function (IIEF) was used. The responses were scored and sexual dysfunction categorised as absent, mild, moderate, or severe. The number of patients receiving help for sexual dysfunction was noted. Neurological examination of the trunk and lower limbs, electromyographic (EMG) evaluation of the sacral reflex, and quantitative EMG of the external anal sphincter muscles were done. RESULTS: Severe sexual dysfunction was reported by 35% of patients, moderate dysfunction by 24%, and slight dysfunction by 26%; normal sexual function was reported by 15%. Orgasmic function was slightly more impaired than erectile function, and sexual desire slightly less. The patients' age, but no findings on clinical neurological or EMG examination, correlated with sexual function. Only five men had received medical attention for sexual dysfunction. CONCLUSIONS: There is significant sexual impairment in men with lesions of the cauda equina or conus medullaris. This is poorly correlated with neurological and EMG findings and has received insufficient medical attention.     

Bilateral vs. unilateral electromyographic examination of the external anal sphincter muscle.

AIM OF THE STUDY: In patients with cauda equina or conus medullaris lesions, bilateral electromyographic (EMG) examination of the subcutaneous external anal sphincter (EAS) muscles has been suggested. In spite of its circular shape, EAS should be considered as two separate semicircular muscles. The aim of the present study was to test the hypothesis that information obtained by bilateral examination of the EAS muscle outweighs inconvenience due to additional needle insertions. PATIENTS AND METHODS: A group of 67 patients with clinical and radiological data supportive of cauda equina or conus medullaris lesion was studied. From the subcutaneous EAS muscles motor unit potentials (MUPs) were sampled by the standard concentric EMG needle electrode, and an advanced EMG system with template operated multi-MUP analysis. Severity of EMG abnormalities was determined, and compared in 48 pairs of the left/right subcutaneous EAS muscles. RESULTS: In 18 patients, bilateral EMG abnormalities were found, in five of them asymmetry of involvement was demonstrated. Unilateral MUP abnormalities were found in 22 patients. The sensitivity of unilateral EMG analysis was 57% and of bilateral examination, 83%. CONCLUSION: In patients with suspected cauda equina lesions, as a rule, bilateral EMG of the subcutaneous EAS muscle is recommended.     

Standardization of anal sphincter electromyography: normative data.

OBJECTIVES: Electromyography (EMG) of the external anal sphincter (EAS) is important in the evaluation of conus/cauda lesions, the differential diagnosis of parkinsonism and anal incontinence. The aim of our study was to establish normative data in a sufficiently large group of healthy subjects, using a rigorously standardized examination technique. METHODS: Sixty-four subjects (aged 19-83 years) without pelvic or neurological disorders were included. Motor unit potentials (MUPs)/interference pattern (IP) samples were obtained from the EAS using multi-MUP and turn/amplitude analyses, respectively. The effect of age, gender, parity, and constipation on MUP/IP parameters was studied. For MUP parameters the lower/upper limits for mean values, and 'outlier' limits, and for IP parameters normal 'clouds' were calculated. RESULTS: From 112 muscles 15-30 MUPs were sampled. As no effect of evaluated factors on mean values could be demonstrated, common reference values were calculated. Lower/higher limits for mean values were: amplitude 148/661 microV, duration 3.2/7.8 ms, area 87/625 microVms, and number of phases 2. 3/3.7. 'Outlier' limits for individual MUPs were: amplitude 84/1315 microV, duration 1.6/13.8 ms, area 46/1222 microVms, number of phases 2/6. From 95 muscles 2706 IP samples were obtained. CONCLUSIONS: The presented normative data should allow valid quantitative EMG of the EAS muscle in patients.     

Electrical stimulation and multichannel EMG recording for identification of functional neural tissue during cauda equina surgery

Electrical stimulation of structures within the surgical field was used to identify functional neural elements during 25 cauda equina operations. EMG responses from anterior thigh, posterior thigh, and anal sphincter muscles were recorded simultaneously using a multichannel signal averager. During nine operations, stimulation of a presumed filum terminale or other tissue produced clear EMG responses, prompting modification of surgical procedures. In one patient, this resulted in preservation of a flattened spinal cord which resembled a band of scar tissue. Some EMG responses were restricted to a single muscle group; these neural structures would probably not have been identified if only a single-channel EMG recording was used. Visual examination alone was not adequate for identifying functional neural elements, or for determining whether atretic-appearing nerve roots were functional. Electrical stimulation with multichannel EMG recording facilitates the preservation of functional neural elements and the optimization of surgical results in cauda equina surgery.     

Gastric and small intestinal dysfunction in spinal cord injury patients

Fynne L, Worsøe J, Gregersen T, Schlageter V, Laurberg S, Krogh K. Gastric and small intestinal dysfunction in spinal cord injury patients.
Acta Neurol Scand: 2012: 125: 123–128.
© 2011 John Wiley & Sons A/S. Background – Many patients with spinal cord injury (SCI) suffer from constipation, abdominal pain, nausea, or bloating, and colonic transit times are prolonged in most. Gastric and small intestinal dysfunction could contribute to symptoms but remain to be described in detail. Also, it is obscure whether the level of SCI affects gastric and small intestinal function. Aim – To study orocecal transit time and gastric emptying (GE) in patients with SCI. Methods – Nineteen patients with SCI (7 ♀, median age 54 years) and 15 healthy volunteers (9 ♀, median age 32 years) were included. All were referred because of neurogenic bowel problems. Eleven patients had low SCI (located at conus medullaris or cauda equina) affecting only the parasympathetic nerves to the left colon and eight had high SCI (above Th6) affecting parasympathetic and sympathetic innervation. Subjects ingested a small magnetic pill that subsequently was tracked by the Motility Tracking System – MTS‐1 (Motilis, Lausanne, Switzerland). Results – Orocecal transit time was longer than normal both in individuals with high lesions (P < 0.01) and in individuals with low lesions (P < 0.01). Individuals with high lesions had slower GE than those with conal/cauda equina lesions (P < 0.05). Basic contractile frequencies of the stomach and small intestine were unaffected by SCI. Conclusion – Surprisingly, upper gastrointestinal transit is prolonged in subjects with SCI suffering from bowel problems, not only in subjects with cervical or high thoracic lesions but also in subjects with conal/cauda equina lesions. We speculate that this is secondary to colonic dysfunction and constipation.     

Colonic transit time, sphincter EMG, and rectoanal videomanometry in multiple system atrophy.

Both constipation and fecal incontinence are prominent lower gastrointestinal tract (LGIT) dysfunctions that occur frequently in multiple system atrophy (MSA). We investigated the mechanism of constipation and fecal incontinence in MSA. Colonic transit time (CTT), sphincter electromyography (EMG), and rectoanal videomanometry were performed in 15 patients with MSA (10 men, 5 women; mean age, 63.5 years; mean duration of disease, 3 years; decreased bowel frequency [< 3 times a week] in 9; difficulty in expulsion in 11; fecal incontinence in 3) and 10 age-matched healthy control subjects (7 men and 3 women; mean age, 62 years; decreased bowel frequency in 2; mild difficulty in expulsion in 2; fecal incontinence in none). Compared to the control subjects, MSA patients had significantly prolonged CTT in the rectosigmoid segment and total colon. Sphincter EMG showed neurogenic motor unit potentials in none of control subjects but in 93% of MSA patients. At the resting state, MSA patients showed a lower anal squeeze pressure (external sphincter weakness) and a smaller increase in abdominal pressure on coughing. During rectal filling, MSA patients showed smaller amplitude in phasic rectal contraction, which was accompanied by an increase in anal pressure that normally decreased, together with leaking in 3 patients. During defecation, most MSA patients could not defecate completely and had larger postdefecation residuals. MSA patients had weak abdominal strain, smaller rectal contraction on defecation, and larger anal contraction on defecation (paradoxical sphincter contraction on defecation), although these differences were not statistically significant. These findings in MSA patients were similar to those in Parkinson's disease patients in our previous study, except for the sphincter denervation and weakness in MSA. Constipation in MSA most probably results from slow colonic transit, decreased phasic rectal contraction, and weak abdominal strain, and fecal incontinence results from weak anal sphincter due to denervation. The responsible sites for these dysfunctions seem to be both central and peripheral nervous systems that regulate the LGIT.     

Comparison of quantitative techniques in anal sphincter electromyography.

Data comparing results and utility of different quantitative electromyographic (EMG) techniques are limited. In the present study, we analyzed the EMG signal from the external anal sphincter (EAS) muscle using three techniques of motor unit potential (MUP) analysis, and a technique of interference pattern (IP) analysis. We examined 56 patients with damage to the cauda equina or conus medullaris, and 64 control subjects. Using manual-MUP and multi-MUP analysis about 20 MUPs, using a single-MUP technique about 10 MUPs, and using turn/amplitude (T/A) analysis about 20 IP samples were obtained. The sensitivities of these techniques in distinguishing neuropathic from control muscles were calculated. The single-MUP technique detected 63%, manual-MUP 57%, and multi-MUP analysis 62% of neuropathic muscles, and MUP parameters obtained by each of these differed significantly from the other. The sensitivity of T/A analysis of IP was 29%. Our results confirm the need for separate MUP normative data for each of the MUP analysis techniques, and favor them over the IP analysis technique. The normative data presented for the EAS muscle should improve and promote quantitative EMG in patients.     

Sacral Nerve Stimulation for Treatment of Intractable Pain Associated with Cauda Equina Syndrome

Sacral nerve stimulation (SNS) is an effective treatment for bladder and bowel dysfunction, and also has a role in the treatment of chronic pelvic pain. We report two cases of intractable pain associated with cauda equina syndrome (CES) that were treated successfully by SNS. The first patient suffered from intractable pelvic pain with urinary incontinence and fecal incontinence after surgery for a herniated lumbar disc. The second patient underwent surgery for treatment of a burst fracture and developed intractable pelvic area pain, right leg pain, excessive urinary frequency, urinary incontinence, voiding difficulty and constipation one year after surgery. A SNS trial was performed on both patients. Both patients'' pain was significantly improved and urinary symptoms were much relieved. Neuromodulation of the sacral nerves is an effective treatment for idiopathic urinary frequency, urgency, and urge incontinence. Sacral neuromodulation has also been used to control various forms of pelvic pain. Although the mechanism of action of neuromodulation remains unexplained, numerous clinical success reports suggest that it is a therapy with efficacy and durability. From the results of our research, we believe that SNS can be a safe and effective option for the treatment of intractable pelvic pain with incomplete CES.     

Predictive value of clinical characteristics in patients with suspected cauda equina syndrome

Background and purpose:  Overlooking a potential diagnosis of cauda equina syndrome (CES) can result in severe long-term neurologic deficits. There is a growing trend to order urgent magnetic resonance imaging (MRI) scans of the lumbar spine in any patient presenting with signs suspicious for CES. A substantial number of these MRI scans do not show cauda compression. The purpose of this study is to assess whether clinical characteristics can predict MRI-confirmed cauda compression.
Methods:  We retrospectively studied 58 consecutive cases of suspected CES who presented at our hospital's emergency room.
Results:  Eight of 58 patients had cauda compression on MRI. When measured, MRI + CES patients (6) had more than 500 ml urinary retention. Moreover, when these patients had at least two of the following characteristics: bilateral sciatica, subjective urinary retention or rectal incontinence symptoms, MRI was more probable to demonstrate cauda compression with an OR of 48.00, 95% (CI 3.30–697.21), which was also significant ( P of 0.04). The presence of other symptoms or signs alone was not significantly different between both groups.
Conclusion:  In our series, urinary retention of more than 500 ml alone or in combination with two or more specific clinical characteristics were the most important predictors of MRI confirmed cauda compressions.     

Electromyography of the anal sphincter: Which muscle to examine?

Electromyographic examination of the deeper external anal sphincter (EAS) muscle is far more uncomfortable than of the subcutaneous muscle, so we tested the need for its examination. We compared the findings in 85 paired examinations of ipsilateral subcutaneous and deeper EAS muscles in 67 patients with a cauda equina lesion. When the other muscle was normal, the deeper or subcutaneous muscle was pathological in 18% or 13% of pairs, respectively. In addition, the subcutaneous EAS muscle was usually more severely affected than the deeper EAS muscle. Thus, examination of the deeper EAS muscle did not increase the sensitivity of MUP analysis significantly, and did not seem clinically necessary.     

What is the optimum methodology for the clinical measurement of resting anal sphincter pressure?

There are conflicting recommendations from consensus groups with regard to the assessment of resting anal sphincter pressure. Our aims were to evaluate and compare the performance of three recognized techniques for the clinical measurement of resting anal sphincter pressure. METHODS: In each of 54 patients presenting for anorectal manometry, and suffering from constipation or fecal incontinence, three different techniques for assessment of resting anal pressure were undertaken, namely stationary, stationary pull-through and slow pull-through techniques. Resting anal sphincter pressures were compared between groups and between techniques. RESULTS: Mean resting anal sphincter pressure was lower with stationary, compared with stationary pull-through and slow pull-through, techniques (P < or = 0.002). Resting pressure was higher for constipation than incontinence regardless of technique used (P < 0.00001). The techniques were highly correlated with each other (P < 0.0001). The stationary pull-through technique conferred a minor advantage in the discrimination between constipation and incontinence. The stationary technique required significantly less time for completion (P < 0.0001). CONCLUSION: Resting anal sphincter pressure varies according to the specific technique employed, yet each technique is valid. The stationary pull-through technique confers a minor advantage in clinical discrimination of patients, but the stationary technique is more time-efficient. Standardized anal sphincter testing should be established to enable inter-laboratory comparisons.     

Rectal hyposensitivity: evaluation of anal sensation in female patients with refractory constipation with and without faecal incontinence.

Rectal hyposensitivity (RH) is commonly found in patients with intractable constipation, faecal incontinence or both. Anal sensation may also be blunted in these conditions. We aimed to determine whether RH is associated with anal hyposensitivity, which may reflect a combined viscero-somatic neuropathy. One hundred and fifty-eight female patients with chronic constipation underwent physiological investigation including rectal sensation to volumetric balloon distension, and distal anal mucosal sensation to electrostimulation. Data were also obtained from 32 healthy female volunteers. Anal mucosal electrosensory thresholds were significantly higher in patients compared with volunteers (median: 2.4 mA, range: 0.4-19.6 vs 1.1 mA, range: 0.1-4.2, respectively), although the patient group was older (P < 0.0001), but there was no difference (P = 0.572) in the incidence of blunted anal sensation between those with normal rectal sensation (n = 113, 20% abnormal) and RH (n = 45, 24% abnormal). Irrespective of rectal sensory function, there was a strong association between symptom duration (P = 0.012) and anal hyposensitivity. One-fifth of constipated female patients had evidence of diminished anal sensation. However, the presence of RH was not associated with an increased frequency of anal hyposensitivity, thereby suggesting that different aetiopathogenic mechanisms underlie the development of anal and rectal hyposensitivity. Further studies in carefully selected, homogenous patient populations are necessary to elucidate these mechanisms.     

神经电生理监测技术在圆锥马尾病变手术中的应用

目的探讨神经电生理监测技术在圆锥马尾病变手术中应用价值。方法回顾性分析110例圆锥马尾病变患者临床资料,其显微外科手术均在神经电生理监测下进行,感觉诱发电位(somatosensory evoked potential,SEP)和运动诱发电位(motor evoked potential,MEP)监测脊髓功能,肌电图(electromyography,EMG)确定肿瘤切除范围。结果显微镜下病变全切除92例(83.6%),次全或大部分切除18例(16.4%)。术后随访1~58个月,神经系统查体及JOA评分发现脊髓神经功能改善102例(92.8%),无变化4例(3.6%),下降4例(3.6%)。对病变切除前与切除后SEP潜伏期和波幅以及MEP潜伏期进行自身比较,脊髓神经功能改善和下降患者电生理监测指标改变差异有统计学意义(P0.05),脊髓神经功能无变化患者相关监测指标改变差异无统计学意义(P0.05),神经电生理监测指标的变化与术后脊髓神经功能改善情况基本相吻合。结论术中神经电生理监测可以实时了解脊髓神经功能的完整性,结合显微神经外科技术可以明显提高圆锥马尾病变的全切率,减少术后并发症,提高手术疗效及安全性。     

Neurourologic findings in conus medullaris and cauda equina injury

Fifty-seven patients with documented conus medullaris and cauda equina injury underwent neurourologic evaluation consisting of cystometrography (CMG), perineal floor electromyography (EMG), and bethanechol chloride supersensitivity testing (BST). The bulbocavernosus reflex was normal in only 16% of the patients, and perineal sensation and muscle stretch reflexes were absent or significantly diminished in 77%. The predominant CMG finding was detrusor areflexia (93%). Neuropathic EMG changes were noted in 67% and a positive BST response in 95% of the cases. Statistical analysis showed significant correlations between (1) a compromised bulbocavernosus reflex and perineal floor neuropathy (.01 less than P less than .05) and (2) sex of the patient and incidence of urinary incontinence among subjects with perineal floor neuropathy (P less than .01). The major neurourologic features in these patients (1) An absent or substantially diminished bulbocavernosus reflex, (2) detrusor areflexia on CMG, (3) neuropathic perineal EMG changes, and (4) a positive BST response.     

Cauda equina syndrome caused by Tarlov's cysts--case report

Perineural Tarlov cysts located on lumbo-sacral roots can be a cause of cauda equina syndrome. OBJECTIVES: 1) To draw attention to the fact that multiple Tarlov lumbo-sacral perineural cysts can produce serious movement disturbances. 2) To document the usefulness of the magnetic resonance imaging in noninvasive diagnosis of perineural cysts. CASE DESCRIPTION: A male patient, 80 years of age, suffered from progressive weakness of lower limbs, which caused an increasing drop of the feet. The disease began in August 2000, following a long journey by train. The patient additionally complained of urinary incontinence as result of sneezing, coughing or fast walking. The urologist did not find prostatic gland hypertrophy. An examination by the internist revealed atheromatous myocardiopathy in circulation failure stage. Magnetic resonance imaging showed multiple perineural cysts up to 15 mm in diameter on lumbo-sacral roots. This clinical picture, supported by the magnetic resonance imaging allowed to recognize cauda equina syndrome caused by Tarlov lumbo-sacral perineural cysts. DISCUSSION: This case is a reminder, that part of perineural cysts, particularly multiple, can be a cause of nerve roots injury, and their lumbo-sacral location can produce cauda equina syndrome. As reported by Zarski and Leo, Tarlov cysts were cause of 7.3% of pain syndrome cases 2 patients in the study group showed lower limb claudication. Magnetic resonance imaging of patients with back pain, performed by Paulsen, Call and Murtagh, revealed that Tarlov cysts occurred in 4.6% of patients, but only 1% had the symptoms connected with the presence of those cysts. In available Polish literature no report has been found referring to fixed cauda equina syndrome which was caused by multiple cysts revealed through the magnetic resonance imaging of spinal canal. Only Zarski and Leo, discussing the correlation between the clinical and radicographic picture, described transient cauda equina syndrome in two patients who, beside Tarlov cysts, were also found to have intervertebral lumbosacral disc herniation. Tarlov was the first to describe well documented cauda equina syndromes caused by cysts on the lumbo-sacral roots. It is necessary to emphasize the established role of magnetic resonance of spinal canal in the diagnosis of perineural cysts on the lumbo-sacral roots as well as other anatomical anomalies of cerebrospinal fluid spaces. Despite the fact that cauda equina syndrome in the case reported here was a serious complication of multiple Tarlov cysts in the lumbo-sacral region, a surgical treatment was not undertaken; in such cases this treatment should be the chosen procedure. CONCLUSION: Multiple perineural Tarlov cysts in lumbo-sacral region, without disc herniation or other cause of vertebral canal stenosis, can produce cauda equina syndrome.     

Malignant peripheral nerve sheath tumor of the cauda equina with craniospinal metastasis

Intradural spinal malignant peripheral nerve sheath tumors (MPNST) are extremely rare, with only 20 adult patients reported to our knowledge, and only four primary tumors arising from the cauda equina. A 49-year-old man presented with back pain, constipation, and lower extremity weakness and was found to have a large intradural lesion involving the cauda equina. Imaging of the rest of his neuraxis revealed additional small left temporal lobe, cervical, and thoracic lesions. The patient underwent laminectomy for tumor debulking and biopsy, as gross total resection was not possible due to envelopment of the cauda equina. Histopathology revealed a MPNST with high cellularity, elevated proliferative indices, and nerve fascicle invasion. After the debulking, the patient reported improvement in his symptoms. However, 6 weeks later, the patient began having severe headaches, and his left temporal lobe lesion was found to have increased significantly in size, requiring craniotomy for palliative resection. The authors report the first adult patient with sporadic spinal MPNST with craniospinal metastasis to our knowledge. Imaging of the entire neuraxis is recommended for initial workup of these lesions, which are capable of intradural spread. The best treatment approach is unclear, but total surgical resection should be attempted, barring infiltration and engulfment of the nerve roots or widespread dissemination.     

Slowed motor conduction in lumbosacral nerve roots in cauda equina lesions: a new diagnostic technique.

New techniques have been developed for the electrophysiological assessment of patients with suspected cauda equina lesions using transcutaneous spinal stimulation (500-1500 V: time constant 50 microseconds) to measure motor latencies to the external and sphincter and puborectalis muscles from L1 and L4 vertebral levels. These latencies represent motor conduction in the S3 and S4 motor roots of the cauda equina between these levels. Similarly motor latencies can be recorded from spinal stimulation to the anterior tibial muscles (L4 and L5 motor roots). Transrectal stimulation of the pudendal nerves is used to measure the pudendal nerve terminal motor latency. In 32 control subjects, matched for age and sex, mean motor latencies from L1 and L4 spinal stimulation were 5.5 +/- 0.4 ms and 4.4 +/- 0.4 ms (mean + SD). In the 10 patients with cauda equina disease including ependymoma, spinal stenosis, arachnoiditis and trauma, these latencies were 7.2 +/- 0.8 ms and 4.6 +/- 0.9 ms, a significant increase in the L1 latency. The L1/L4 latency ratios to the puborectalis muscle were 1.36 +/- 0.09 in control subjects and 1.72 +/- 0.13 in cauda equina patients. Pudendal nerve terminal motor latencies were normal in eight of the 10 patients with cauda equina disease. The single fibre EMG fibre density in the external and sphincter muscle (normal, 1.5 +/- 0.16) was increased in patients with cauda equina lesions (1.73 +/- 0.28), but was increased more than two standard deviations from the mean only in three patients. This increase in fibre density was not of diagnostic value since it was also found in two of the four patients with low back pain. Slowing of motor conduction in the cauda equina is thus a useful indication of damage to these intraspinal motor roots. These investigations can be used in the selection of patients for myelography, and to follow progress in patients managed conservatively.     

C5b-9 TERMINAL COMPLEX ACTIVATION IN CHRONIC INFLAMMATORY DEMYELINATING NEUROPATHY

Aim of the Study : Amplify neurological balance in patients with recent vertebral spinal cord disease to establish the extension and gravity of damage on anterior horn cells, motor and sensory roots and the presence of entrapment neuropathies.
Materials and Methods: Fourteen consecutive patients (13 males and 1 female), mean age: 42.9 years (range 24–65), an interval of time from lesion>1 and < 3 months with cervical lesions in nine cases and lumbosacral lesions in five cases. Central and peripheral nervous system and/or systemic diseases preceding trauma were excluded. Besides neurological evaluations and vertebral NMR/CT, standard EMG were performed: motor (M) and sensory (S) nerve conductions (NC), F-wave study, and extensive muscular needle study differentiated in relation to cervical or lumbosacral side of lesion.
Results: In cervical traumas 5 subjects showed complete medullar transversal lesion (C8-T1 in 4 cases, C7 in 1 case) and 4 subjects incomplete lesion. EMG data: show amplitude CMAP in 5 subjects, MNC reduction in 4 patients, F-Wave absence in 1 case. Normal SNC in 7 cases. No observed relation between gravity of clinical palsy and EMG alterations. At needle examination frequently presence of alterations often also over and under clinical level spinal cord lesion. In lumbar trauma we verified 3 cases with complete medullar palsy and 2 cases cauda equina syndrome as clinical aspects. EMG data: extreme MNC alterations in 2 of 3 cases with medullar palsy (normal in 1 case). In 2 cases with cauda equina syndrome we observed strict concordance between clinical and EMG aspects.
Conclusions: EMG can usefully propose as systematically associated investigation in patients with post-traumatic spinal cord diseases in order to define the localization and the gravity of neurological lesion and the contribution of lower motor neuron lesion to clinical palsy.     

Saddle sensation is preserved in a few patients with cauda equina or conus medullaris lesions1

Although saddle sensory deficit seems the most useful clinical sign in the diagnosis of a cauda equina or conus medullaris lesion, findings of previous studies were controversial. The aim of the present study was to try to resolve this issue. The data from the author's series of patients with clinical, electrodiagnostic and radiological findings compatible with a cauda equina lesion were reviewed. Of the 117 patients in the series, 11 (10 men) did not have a saddle sensory deficit. These 11 patients had less severe sacral dysfunction than the others, and none of them needed urgent surgical intervention. They all had electromyographic (EMG) signs of a significant motor fibre lesion, and in seven men the sacral (penilo‐cavernosus) reflex was clinically abnormal. The study revealed normal saddle sensation in approximately 10% of patients with cauda equina or conus medullaris lesions. Dissociation between preserved touch sensation and abnormal EMG findings, as well as dissociation between preserved touch sensation and a non‐elicitable penilo‐cavernosus reflex might be explained by preservation of the thinner sensory nerve fibres, which are more resistant to compression. Although, saddle sensory loss seems to identify patients who might benefit from urgent spinal imaging and surgery, further diagnostic evaluation is also indicated in patients with normal saddle sensation, particularly due to the increased frequency of spinal tumours found in this subgroup.     

Cauda equina syndrome secondary to long-standing ankylosing spondylitis

Fourteen patients with cauda equina syndrome secondary to long-standing ankylosing spondylitis are described. The roughly symmetrical neurological deficits were very slowly progressive and began long after the onset of the spondylitis, usually well after the rheumatological symptoms had stopped. Eventually every patient had cutaneous sensory loss in the fifth lumbar and sacral dermatomes. All patients developed urinary sphincter disturbances of a lower motor neuron type. There was prominent loss of rectal sphincter tone, and all but 2 patients had bowel complaints, including incontinence and severe constipation. Seven patients had mild to moderate weakness in the lumbosacral myotomes. Seven patients had pain in the rectum or lower limbs. Electromyographic abnormalities were consistent with multiple lumbosacral radiculopathies. Myelography and computed tomographic scanning of the lumbosacral spine showed characteristic enlargement of the caudal sac and dorsal arachnoid diverticula that had eroded the laminae and spinous processes. Recognition of this syndrome, coupled with computed tomographic scanning of the lower spinal canal, allows one to omit myelography, a procedure that is difficult because of the associated spine abnormalities. Surgical intervention should be avoided.