Evaluation of children and young adults with tethered spinal cord syndrome. Utility of spinal and scalp recorded somatosensory evoked potentials

Lumbosacral posterior meningocele in adult patient: a case report

Spinal dysraphism is the incomplete fusion of the neural arch, which can be seen as an occult or open neural tube defect. Meningoceles are a form of open neural tube defect characterized by cystic dilatation of the meninges containing cerebrospinal fluid without the involvement of neural tissue. Neurosurgical intervention is necessary in the newborn period since survival in advancing ages is often impossible. Therefore, meningoceles are rarely reported in adulthood. Here, we discussed a case of a 23-year-old female who presented with a meningocele in the lumbosacral area since birth, which had not been operated on. Surgical management and intraoperative findings are also discussed.

Determination of tibial somatosensory evoked potentials predicts detrusor sphincter dyssynergia in children with neurogenic bladder dysfunction

INTRODUCTION

Tibial somatosensory evoked potentials (SEP) are used to identify the neurological status and tethered cord (TC) in patients with spina bifida (SB). Its significance in contributing to the interpretation of urodynamics to determine bladder status is unknown. This study aimed to determine the correlation between SEP and urodynamics in children with SB.

MATERIAL AND METHODS

SEP and urodynamic results, for differential diagnosis of TC, were evaluated. SEP scores were correlated with urodynamic findings. SEP results were scored from 1 to 6, with 1, denoting a favorable score and 6, an unfavorable score. Age, gender, detrusor, and sphincter activities in urodynamics were noted. Results were analyzed using the χ² test and logistic regression analysis. Receiver operating characteristic (ROC) curve was formed to get a valid threshold for the SEP score to predict the urodynamic condition.

RESULTS

There were 44 SB patients for whom SEP was done for differential diagnosis of TC. Fifteen patients who did not meet the inclusion criteria were excluded from the study. SB aperta was present in 17 patients and occulta in 12, respectively. The patients had a mean age of 6.6 ± 3.2 years. There were 13 boys and 16 girls. A strong correlation was found between high SEP scores and detrusor sphincter dyssynergia (p < 0.001). A SEP score over 3.5 was found to be 93% sensitive and 73% specific to predict this correlation. There was no relationship between detrusor activity and SEP scores (p = 0.18).

DISCUSSION

Tibial SEP is an important noninvasive adjunct tool for the diagnosis of TC in patients with SB. Urodynamic studies are the gold standard in the evaluation of bladder status in neurogenic bladder dysfunction due to SB. Detrusor sphincter dyssynergia may be regarded as a sign of severe spinal cord injury in these patients.

CONCLUSION

Our findings suggest that in children with neurogenic bladder, high SEP scores may predict the presence of detrusor sphincter dyssynergia but not the status of detrusor function while providing pathophysiological evidence for neural injury.

Electrodiagnostic findings of retethering in children with spinal dysraphism

PURPOSE

Retethering of the cord can occur after the initial untethering surgery. Typical neurological manifestations indicative of cord tethering are often difficult to determine in pediatric patients. Patients who had a primary untethering operation are likely to present with some degree of neurological deficits from a previous tethering event, and urodynamic studies (UDSs) and spine images are frequently abnormal. Therefore, more objective tools to detect retethering are needed. This study sought to delineate the characteristics of EDS of retethering, and therefore, could support the diagnosis of retethering.

METHODS

Among 692 subjects who had an untethering operation, data from 93 subjects who had been suspected of retethering clinically were retrospectively extracted. The subjects were divided into two groups, a retethered group, and a non-progression group, according to whether or not surgical interventions had been performed. Two consecutive EDSs, clinical findings, spine magnetic resonance imaging scans, and UDSs before the development of new tethering symptoms were reviewed and compared.

RESULTS

In the electromyography (EMG) study, the appearance of abnormal spontaneous activity (ASA) in new muscles was prominent in the retethered group (p < 0.01). The loss of ASA was more pronounced in the non-progression group (p < 0.01). Specificity and sensitivity of EMG for retethering were 80.4 and 56.5%, respectively. In the nerve conduction study, the two groups did not show differences. The size of fibrillation potential was not different between the groups.

CONCLUSIONS

To provide support for a clinician's decision on retethering, EDS could be an advantageous tool with high specificity when the results are compared to previous EDS results. Routine follow-up EDS post-operatively is recommended as a baseline for comparison at the time when retethering is clinically suspected.

Dynamic MRI in the Evaluation of Atlantoaxial Stability in Pediatric Down Syndrome Patients

BACKGROUND/AIMS

Down syndrome is the most common inherited disorder. Some patients develop atlantoaxial instability. Existing screening guidelines were developed prior to availability of MRI. We present predictors for deficit using dynamic MRI of the craniocervical junction.

METHODS

A retrospective review of Down syndrome patients from 2001 to 2015 was carried out. Patients were considered symptomatic if they had clinical deficits or signal change on MRI. Measurements were taken at the atlantoaxial junction and structural abnormalities noted. Analysis was performed with SPSS.

RESULTS

A total of 36 patients were included. Patients averaged 93 months of age with a follow-up of 57 months. No asymptomatic patients developed myelopathy during follow-up. During dynamic imaging, symptomatic patients had greater changes in space available for the cord (SAC) (5.2 vs. 2.7 mm; p < 0.001) and atlantodental interval (ADI) (2.8 vs. 1.3 mm; p = 0.04). These patients were also more likely to have a bony anomaly (50 vs. 13%; p = 0.03).

CONCLUSION

This study characterizes the range of motion seen on dynamic MRI and provides parameters that can be used to distinguish patients at risk for neurologic injury. Changes greater than 3 mm in ADI or 5 mm in SAC during dynamic MRI or any bony abnormality warrants further investigation. Patients without these features may be able to avoid an unnecessary intervention.

Magnetic resonance imaging in the prone position and the diagnosis of tethered spinal cord

OBJECTIVE Tethered cord syndrome (TCS) is a neurosurgical disorder with varied clinical manifestations believed to result from vascular compromise due to stretch forces on the spinal cord. Conventional supine MRI findings may include a low-lying conus medullaris, thickened or fat-infiltrated filum terminale, or lipoma; however, imaging sensitivity and specificity for tethered cord can be low. The purpose of this study was to evaluate the utility of prone MRI in the diagnosis of tethered and retethered spinal cord. METHODS Medical records were reviewed in 41 patients who underwent surgical release of tethered cord and in whom preoperative prone MRI sequences were available. Patients were divided into Group 1 (new TCS diagnosis) and Group 2 (recurrent TCS after previous untethering). Absolute conus ventral motion and motion as a percentage of canal width between supine and prone positions was measured in these 2 groups via sagittal T2-weighted sequences; these groups were compared with 30 consecutive patients (Group 3) who were classified as the normal control group. RESULTS The mean ventral motion was as follows: Group 1 (absolute: 0.5 ± 0.5 mm [range 0-2.4 mm]; canal percentage: 3.7% ± 3.9% [range 0%-16.3%]); Group 2 (absolute: 0.4 ± 0.7 mm [range 0-2.6 mm]; canal percentage: 2.2% ± 3.7% [range 0%-14.0%]); and Group 3 (absolute: 3.4 ± 1.3 mm [range 1.4-5.6 mm]; canal percentage: 22.0% ± 7.2% [range 10.5%-36.1%]). Whereas 38/41 surgically treated patients with TCS had diminished (< 10% canal width) ventral motion on preoperative MRI, 30/30 controls had > 10% canal width motion. Sensitivity and specificity were thereby calculated as 92.7% and 100%, respectively. CONCLUSIONS In the present series, prone imaging is found to be a sensitive and specific tool, and the authors believe it may have a role as supportive evidence in the diagnosis of tethered and retethered spinal cord.

Intraoperative neurophysiology in tethered cord surgery: techniques and results

INTRODUCTION

Intraoperative neurophysiologic monitoring (IOM) is nowadays extensively used to minimize neurological morbidity in tethered cord surgery. Our goal is to describe and discuss the standard IOM techniques used during these surgical procedures and to summarize our clinical experience using a multimodal IOM approach.

MATERIAL AND METHODS

Neurophysiological mapping of the conus-cauda is performed through direct stimulation of these structures and bilateral recording from segmental target muscles. While mapping identifies ambiguous neural structures, their functional integrity during surgery can be assessed by monitoring techniques only, such as somatosensory evoked potentials (SEPs), transcranial motor-evoked potentials (MEPs) from the limb muscles and anal sphincters, and the bulbocavernosus reflex (BCR).

RESULTS

Between 2002 and 2012, we performed 48 surgical procedures in 47 patients with a tethered cord secondary to a variety of spinal dysraphisms. The monitorability rate was 84 % for SEPs, 97 % for limb muscle MEPs, 74 % for the anal sphincter MEPs, and 59 % for the BCR. In all patients but one, SEP, MEP, and BCR remained stable during surgery. Postoperatively, two out of 47 patients presented a significant-though transient-neurological worsening. In six patients, an unexpected muscle response was evoked by stimulating tissue macroscopically considered as not functional.

CONCLUSIONS

Mapping techniques allow identifying and sparing functional neural tissue and vice versa to cut nonfunctional structures that may contribute to cord tethering. Monitoring techniques, MEP and BCR in particular, improve the reliability of intraoperative neurophysiology, though these may require a higher degree of neuromonitoring expertise. IOM minimizes neurological morbidity in tethered cord surgery.

Management of recurrent adult tethered cord syndrome

Recurrent tethered cord syndrome (TCS) can lead to significant progressive disability in adults. The diagnosis of TCS is made with a high degree of clinical suspicion. In the adult population, many patients receive inadequate care unless they are seen at a multidisciplinary clinic. Successful detethering procedures require careful intradural dissection and meticulous wound and dural closure. With multiple revision procedures, vertebral column shortening has become an appropriate alternative to surgical detethering.

Adult tethered cord syndrome mimicking lumbar disc disease

OBJECT

This paper reports four tethered cord cases who initially applied with lumbar disk disease symptoms.

MATERIALS AND METHODS

All of them were investigated by magnetic resonance imaging (MRI) and somatosensory evoked potential (SSPE). In two patients, MRI revealed thick and fatty filum terminale, while in remaining two, the filum terminale appeared as normal in thickness. SSEP revealed pathological conduction values in all, and it was the main indicator for surgical sectioning in patients especially with normal MRI investigations. All patients had benefit from the surgical sectioning of the fila terminalia with either thick and fatty or normal appearance.

CONCLUSION

A particular patient with lumbar disc disease symptoms having normal MRI should also be investigated for tight filum terminale. If there is no pathological appearance in MRI investigation (both in regard to disc herniation and thick and fatty filum terminale), SSEP investigation should be done to check whether a conduction block or delay is present, indicating cord tethering.

Adult tethered cord syndrome in patients with postrepair myelomeningocele: an evidence-based outcome study

OBJECT

As patients with myelomeningocele age, tethered cord syndrome (TCS) in adults with postrepair myelomeningocele has become more common. The authors have structured an evidence-based review of the literature for the purpose of addressing the following questions. (1) How is the diagnosis made? (2) What is the natural history that occurs in adults with postrepair myelomeningocele and TCS? (3) What are the criteria for operative intervention? (4) What is the functional outcome for patients with postrepair myelomeningocele?

METHODS

A computerized search of the National Library of Medicine of the English-language literature published from 1966 to 2003 was performed. Articles pertaining to the clinical aspects and management of postrepair myelomeningocele in adults, TCS in adults resulting from closed defects, and pediatric patients with postrepair myelomeningocele were reviewed. No Level 1 or 2 data were located; however, the search yielded Level 3 and 4 evidence in the literature in which the clinical syndrome, underlying pathology, and the imaging and electrophysiological evaluation for TCS in adults are discussed.

CONCLUSIONS

Analysis of the available data indicates the following. (1) A lower lesion level predisposes patients to symptomatic tethering; moreover, orthopedic and urological deterioration will occur in the majority of these patients. (2) Tethered cord release should be considered for adult patients with postrepair myelomeningocele when clinical symptoms, imaging studies, urodynamics, and somatosensory evoked potentials are consistent with TCS. (3) Prompt, aggressive untethering surgery within 5 years of symptom onset, along with long-term follow up to check for delayed retethering, is recommended. The overall outcome for patients with postrepair myelomeningocele may not be as good as the outcome for adults with closed dysraphism.

The initial treatment of meningocele and myelomeningocele lesions in adulthood: experiences with seven patients

This is a retrospective study of patients having undergone surgical treatment of spina bifida cystica (SBC) lesions in adulthood. The objectives were to assess the clinical, radiological, and surgical characteristics of SBC lesions in adults. There is almost no study assessing these characteristics. Seven adult male patients with SBC lesions, ages between 20 and 23 (mean 21.1), had their primary evaluations between 1995 and 1999 in the Military Hospital, Yzmir, and Gülhane Military Medical Academy, Ankara. A temporary cerebrospinal fluid leak in the patient with the thoracic lesion and a temporary partial urinary incontinence in the patient with the lumbosacral lesion occurred. The most common preoperative complaint was low back pain. This improved in three of four patients (75%) but did not disappear. Although it is rare, an adult with an untreated SBC is a possible entity. These lesions should be included in the differential diagnosis of dorsal midline lesions in adults. Even though they appear as a simple spinal meningocele clinically, preoperative MR imaging and CT are necessary and helpful in the precise diagnosis and surgical planning.

Evoked potential abnormalities in postoperative patients with biliary atresia

The somatosensory evoked potentials from the lower extremities were measured postoperatively in 15 patients with biliary atresia to investigate whether they were free of neurologic dysfunction. Because long-standing cholestasis causes progressive neuropathy due to malabsorption of vitamin E, the serum vitamin E, D, and A levels were also examined to evaluate the fat-soluble vitamin status. The cerebral evoked potentials to posterior tibial nerve stimulation were recorded in all 15 patients as well as in 45 controls, but spinal evoked potentials examined at the level of the cauda equina could not be recorded in five patients more than 8 years of age with long-standing icterus. The remaining 10 patients exhibited spinal evoked potentials as observed in the controls, but the mean neural conduction velocity at the cauda equina was significantly lower than that of the 45 controls (42.0 +/- 5.1 m/s vs 52.3 +/- 6.8 m/s, P = .0002). The serum vitamin E, D, and A levels were within the normal range in 13, 9, and 1 of 15 patients, respectively. These results suggest that the patients with long-term follow-up are still at risk of developing neural disturbances even with normal serum vitamin E status.

Spinal somatosensory evoked potentials in patients with tethered cord syndrome

We studied the electrophysiological changes occurring in six patients with tethered cord syndrome. Evidence of spinal malformations was provided by magnetic resonance imaging. The functional assessment of the spinal cord was performed by analysing both spinal and cortical somatosensory evoked potentials. The evoked electrospinogram was recorded from the thoracic and lumbosacral spinous processes. The N22 lumbosacral potential was selectively affected, being rostrocaudally displaced and reduced in amplitude or even absent in patients with neurological signs indicating a segmental lower cord lesion. Inter-peak somatosensory evoked potentials latency was normal in all cases, suggesting that ascending axonal potentials in the dorsal column fibres may be synchronized. Segmental potentials of the lumbosacral response, originating from the post-synaptic activity of dorsal horn interneurons, are selectively affected in this syndrome resulting from the rostrocaudal displacement of the spinal cord due to tethering. Our findings in the clinical field are consistent with previous experimental evidence indicating a different sensitivity of the gray vs. white matter to progressive stretching.

Childhood back pain: diagnostic evaluation of an unusual case

Low back pain is uncommon in children. The case of a 5-year-old boy presenting with back pain that proved to be caused by a metastatic primitive neuroectodermal tumor is presented and the evaluation of such patients is discussed.

Tethered cord after spina bifida aperta: a longitudinal study of somatosensory evoked potentials

Progressive neurological deterioration may occur after meningomyelocele repair. Magnetic resonance imaging almost invariably demonstrates a conus medullaris in an abnormally low position, whether neurological symptoms develop or not. Surgery of a secondary tethered cord is indicated when progression of neurological symptoms is documented. We performed a longitudinal study of posterior tibial nerve somatosensory evoked potentials (SSEPs) in children and adolescents after neonatal meningomyelocele repair. All patients were able to walk. Declining or negative posterior tibial nerve SSEPs were recorded in 15 patients; 14 of these had clinical signs of a secondary tethered cord. After surgery of the tethered cord, the SSEPs improved in 8 of 10 patients. Posterior tibial nerve SSEPs may contribute to the diagnosis of secondary tethered cord. After untethering, the evoked potentials demonstrate recovery of spinal cord function and might help to delineate prognosis.

Tethered cord syndrome in myelodysplasia: correlation between level of lesion and height at time of presentation

The purpose of this study was to determine whether the onset of tethered cord syndrome is related to the level of the myelomeningocele (MMC) (sacral, low lumbar, high lumbar or thoracic) and the height and age of the patient at time of presentation. Of 163 patients followed, 18 underwent corrective surgery for symptomatic tethered cord syndrome. The level of lesion at time of presentation correlated highly with height and age. The mean height and age for each level at the time of surgery were: sacral 134.5cm, 9.3 years; low lumbar: 124cm, 9.9 years; high lumbar: 108cm, 4.9 years; thoracic: 92.4cm, 4.7 years. The author concludes that the sensorimotor level of patients with MMC is a useful clue in predicting the onset of symptoms related to tethered cord syndrome.

Review of tethered cord syndrome with a radiological and anatomical study: case report

The primary tethered cord syndrome has been documented mainly in children and adolescents but also in adults, and patients may present with backache, neuromuscular skeletal changes such as club-foot, scoliosis, muscular atrophy, disturbances of gait, or dysfunction of bladder and rectum, or a combination of these conditions. The cadaveric case presented describes plain film radiographic and anatomical findings of spina bifida occulta at the first and second sacral levels, and an enlarged spinous process of the fifth lumbar vertebra, in a 78 year old male cadaver with a tethered spinal cord terminating at the first sacral level. During life, this man had not undergone surgery for tethered spinal cord.

Tethered cervical spinal cord. Case report

A case of congenital tethered cervical spinal cord is presented in a young adult. Metrizamide computerized tomography was the most useful imaging technique for identifying the tethered spinal cord. Intraoperative somatosensory evoked potentials correlated well with clinical improvement following surgery.

Development of lumbar spinal cord and cortical evoked potentials after tibial nerve stimulation in the pre-term newborns: effects of gestational age and other factors

Pre-term neonates are at increased risk for neurological dysfunction. Several investigators have found scalp recorded somatosensory evoked potential studies (SSEPs) after median nerve stimulation useful in the evaluation of newborn infants with asphyxiation and the effects of other adverse prenatal and perinatal factors. In order to evaluate the entire developing neuraxis, we undertook SSEPs after tibial nerve stimulation (PTN-SSEP) in pre-term neonates. Using bilateral simultaneous stimulation, potentials were recorded from the following sites: PF-spT6 (N5), spL1-spT6 (N16), spC7-Fpz (N27), Cz' (1 cm behind the vertex)-Fpz (P55). In all newborns studied, the N5 and N16 were reliably recorded. The N5 appeared relatively independent of the length of the newborns. The N16 correlated inversely with length. The N27 and P55 were recorded in 52% and 65% of the newborns, respectively. N27 inversely correlated modestly with length. The P55 was independent of most factors and probably reflects variable rates of cerebral myelination, neuronogenesis, varying states of alertness, and possibly subclinical encephalopathies. These results demonstrate the feasibility of obtaining such data in pre-term newborns.