Tethered cord syndrome in adults and children

Three-Dimensional Sonographic Evaluation of the Position of the Fetal Conus Medullaris at First Trimester

OBJECTIVE

The objective of this study was to assess the position of the conus medullaris (CM) at the first trimester 3D ultrasound in a cohort of structurally normal fetuses.

METHODS

This was a multicenter prospective study involving a consecutive series of structurally normal fetuses between 11 and 13 weeks of gestation (CRL between 45 and 84 mm). All fetuses were submitted to 3D transvaginal ultrasound using a sagittal view of the spine as the starting plane of acquisition. At offline analysis, the position of the CM was evaluated by 2 independent operators with a quantitative and a qualitative method: (1) the distance between the most caudal part of the CM and the distal end of the coccyx (CMCd) was measured; (2) a line perpendicular to the fetal spine joining the tip of the CM to the anterior abdominal wall was traced to determine the level of this line in relation to the umbilical cord insertion (conus to abdomen line, CAL). Interobserver agreement for the CCMd was evaluated. Linear regression analysis was used to determine the association between the CMCd and CRL, and a normal range was computed based on the best-fit model. The absence of congenital anomalies was confirmed in all cases after birth.

RESULTS

In the study period between December 2019 and March 2020, 143 fetuses were recruited. In 130 fetuses (90.9%), the visualization of the CM was feasible. The mean value of the CMCd was 1.09 ± 0.16 cm. The 95% limits of agreement for the interobserver variability in measurement of the CMCd were 0.24 and 0.26 cm. The interobserver variability based on the intra-class correlation coefficient (ICC) for the CCMd was good (ICC = 0.81). We found a positive linear relationship between the CCMd and CRL. In all these fetuses, the CAL encountered the abdominal wall at or above the level of the cord insertion.

CONCLUSION

In normal fetuses, the assessment of the CM position is feasible at the first trimester 3D ultrasound with a good interobserver agreement. The CM level was never found below the fetal umbilical cord insertion, while the CMCd was noted to increase according to the gestational age, confirming the "ascension" of the CM during fetal life.

Spinal shortening osteotomy for adult tethered cord syndrome evaluated by intraoperative ultrasonography

BACKGROUND

Spinal shortening osteotomy (SSO) reduces the tension indirectly in the spinal cord and minimizes perioperative complications. However, the most effective and safe length to which the spine can be shortened is still unknown. In our practice, we use somatosensory-evoked potentials, motor-evoked potentials, and intraoperative ultrasonography when performing SSO. This study aimed to introduce the clinical outcomes of our SSO technique for tethered cord syndrome (TCS) in adults.

METHODS

This retrospective study included 7 adult patients (2 males and 5 females) with TCS treated between December 2010 and December 2018. The average age and average preoperative duration were 40 and 5 years, respectively. All patients received SSO with somatosensory-evoked potentials, motor-evoked potentials, and ultrasonography. After surgery, all patients were followed for an average of 4 years.

RESULTS

The mean operation time was 328 (284-414) min for SSO. The mean blood loss was 828 ml (501-1252 ml). Postoperative bony fusion was confirmed in all patients. Postoperative computed tomography (CT) demonstrated an average of 16 mm (11-20 mm) of spinal column shortening, compared with preoperative CT. Clinical improvements were obtained in all 7 cases, and there was no case of exacerbation. An indicator of shortening is that the ultrasonography gives pulsation and relaxation of the spinal cord. There were no abnormalities observed while monitoring the spinal cord.

CONCLUSIONS

Spinal shortening should be done under somatosensory-evoked potentials, motor-evoked potentials, and intraoperative ultrasonography to obtain safe and sufficient shortening.

Secondary tethered cord syndrome in adult patients: retethering rates, long-term clinical outcome, and the effect of intraoperative neuromonitoring

BACKGROUND

The strategy for surgical treatment of tethered cord syndrome in pediatric patients is well established but still bares challenges for adult patients. This retrospective study was performed to assess the surgical outcome of adult patients with a secondary tethered cord syndrome and to evaluate the benefit of intraoperative neuromonitoring.

METHODS

Clinical charts of 32 consecutive adult patients who underwent in total 38 surgical untethering procedures at our facility between 2008 and 2018 were retrospectively analyzed. Epidemiological data, MRI scans, and postoperative results were evaluated.

RESULTS

The retethering rate in our patient cohort was 16%. Main complaints were maximal pain (82%), bladder dysfunction (79%), paresthesia (68%), and weakness in the lower extremities (68%). Forty-eight months after surgery, patients' symptoms generally improved, with an average level of pain of 19.1% (95% CI, 5.7-32.5%), paresthesia 28.7% (95% CI, 12.6-44.8%), weakness in the lower extremities 27.7% (95% CI, 11.1-44.4%), and bladder dysfunction 60.2% (95% CI, 41.6-78.7%). The use of neuromonitoring appears to have a positive impact on patient weakness (OR = 0.07; 95% CI, 0.01-0.68) and paresthesia (OR = 0.03; 95% CI, 0.00-2.18). This benefit is less clear for the retethering rate (OR = 0.45; 95% CI, 0.06-3.26) or the overall clinical outcome (OR = 0.70; 95% CI, 0.14-3.45). The presence of a preoperative Chiari syndrome, syringomyelia, or scoliosis had no relevant influence on the retethering rate.

CONCLUSIONS

Our data confirms that untethering surgery in adult patients is relatively safe and has a reasonable chance of clinical improvement of pain, paresthesia, and weakness in the lower extremities. The use of intraoperative monitoring has a positive influence on the improvement of preoperative paralysis.

Spinal column shortening versus revision detethering for recurrent adult tethered cord syndrome: a preliminary comparison of perioperative and clinical outcomes

OBJECTIVE

Recurrent tethered cord syndrome (TCS), believed to result from tension on the distal portion of the spinal cord, causes a constellation of neurological symptoms. Detethering surgery has been the traditional treatment for TCS. However, in cases of recurrent TCS, there is a risk of new neurological deficits developing, and subsequent retethering is difficult to prevent. Spinal column shortening has been proposed as an alternative technique to reduce the tension on the spinal cord without incurring the morbidity of revision surgery on the spinal cord. The authors compared the perioperative outcomes and morbidity of patients who were treated with one or the other procedure.

METHODS

The medical records of 16 adult patients with recurrent TCS who were treated between 2005 and 2018 were reviewed. Eight patients underwent spinal column shortening, and 8 patients underwent revision detethering surgery. Patient demographics, clinical outcomes, and perioperative factors were analyzed. The authors include a video to illustrate their technique of spinal column shortening.

RESULTS

Within the spinal column shortening group, no patients experienced any complications, and all 8 patients either improved or stabilized with regard to lower-extremity and bowel and bladder function. Within the revision detethering group, 2 patients had worsening of lower-extremity strength, 3 patients had worsening of bowel and bladder function, and 1 patient had improvement in bladder function. Also, 3 patients had wound-related complications. The median estimated blood loss was 731 ml in the shortening group and 163 ml in the revision detethering group. The median operative time was 358 minutes in the shortening group and 226 minutes in the revision detethering group.

CONCLUSIONS

Clinical outcomes were comparable between the groups, but none of the spinal column shortening patients experienced worsening, whereas 3 of the revision detethering patients did and also had wound-related complications. Although the operative times and blood loss were higher in the spinal column shortening group, this procedure may be an alternative to revision detethering in extremely scarred or complex wound revision cases.

Clinical Notes on Chiari Malformation

Chiari malformations (CMs) are variant structural setup of cerebellum and brain stem at the craniovertebral junction. Normally the cerebellum and parts of the brain stem lie above the foramen magnum. When the part of the cerebellum and/or brainstem protrudes into the upper spinal canal through foramen magnum, it is defined as CM. Chiari malformations may develop when part of the skull is smaller than normal or misshapen, due to which the cerebellum herniates into spinal canal through foramen magnum. This compresses the cerebellum and brainstem affecting functions controlled by these parts and blocks the flow of cerebrospinal fluid that surrounds and cushions the brain and spinal cord. Chiari malformation may cause sensory loss, ataxia, weakness, nystagmus, spastic limbs to name a few. Thus, various morbid and mortal neurologic disorders result from CM. Therefore, sound and thorough knowledge of CM and its variant anatomy are essential for diagnosis and management of neurologic disorders. Therefore, review study has been carried out for updating and consolidating the knowledge of all the variations of CMs. Literature search was carried out using databases, SciELO, ScopeMed, MEDLINE, PubMed, and Wiley Online Library. Papers containing original data were selected and secondary references retrieved from bibliographies. Various terms related to CMs were used for net surfing. The knowledge will be of immense importance to neurologists and neurosurgeons to diagnose and treat the CMs and decrease the mortality associated with CM and to radiologists for correctly interpreting the magnetic resonance imaging.

Mechanical relationship of filum terminale externum and filum terminale internum: is it possible to detether the spinal cord extradurally?

INTRODUCTION

Intradural transection of the filum terminale (FTI) is often used to treat tethered cord syndrome. Recently, some have proposed that the extradural part of the filum terminale (FTE) can be sectioned with equal results but with fewer complications. Therefore, the present cadaveric study aimed to evaluate the anatomical foundation of such procedures.

METHODS

A posterior lumbosacral approach was performed on five fresh-frozen cadaveric specimens to expose both the FTI and FTE. Tension was then applied to the FTE and observations and measurements made of any movement of the FTI. Other morphological measurements (e.g., length, diameter) of the FTI and FTE were also made.

RESULTS

Although very minimal movement of the FTI was seen in the majority of specimens following tension on the FTE, no specimen was found to have more cranial movement of the conus medullaris or cauda equina. The mean length and diameter of the FTI was 52.2 and 0.38 mm, respectively. The mean length and diameter of the FTE was 77 and 0.60 mm, respectively. The force necessary to move the FTI with tension applied to the FTE had a mean of 0.03 N. The average distance that the FTI moved with distal FTE tension was 1.33 mm. All specimens had a thecal sac that terminated at the S2 vertebral level. And no specimen had a low-lying conus medullaris, cutaneous stigmata of occult spinal dysraphism, or grossly visible adipose tissue in either the FTI or FTE.

CONCLUSIONS

Based on our studies, tension placed on the FTE has very little effect on the FTI and no obvious effect on the conus medullaris or cauda equina. Therefore, isolated transection of the FTE for a patient with tethered cord syndrome is unlikely to have significant effect. To our knowledge, this is the first study to quantitate the distal forces needed on the FTE to move the FTI.

Urodynamic outcomes of detethering in children: experience with 46 pediatric patients

AIM

Tethered cord syndrome (TCS) manifests with neurological and urological complaints. Surgical detethering is the main treatment for TCS. Children with urological symptoms are required objective pre- and postoperative evaluations in order to predict urological outcome. The aims of this study are to investigate the effects of detethering procedure on the urodynamic tests and to determine the relationship between the changes of urodynamic tests and the patients' age and gender.

MATERIAL AND METHODS

The data of urodynamic tests in 46 pediatric patients, who underwent surgery for TCS, were retrospectively evaluated. Bladder capacity, post-voiding residual urine volume, maximum intravesical pressure, and bladder compliance of each patient were measured in preoperative period and at the third month after surgery. These parameters were statistically compared, and the correlations of these parameters with age, gender, and etiology of the TCS were also investigated.

RESULTS

Bladder capacity and post-voiding residual urine volume were decreased and maximum intravesical pressure and bladder compliance were increased after surgery for TCS. The decrease in bladder capacity was significant in patients older than 10 years (p < 0.05). The increase in maximum intravesical pressure was also positively correlated with age (p < 0.05). But the increase in bladder compliance was negatively correlated with age (p < 0.05).

CONCLUSION

Bladder capacity, post-voiding residual urine volume, and bladder compliance are mainly affected by surgery in patients with TCS. From the urological viewpoint, children older than 10 years are most likely to benefit from surgery for TCS.

Elderly-onset degenerative "lumbar spondylotic myelopathy" in a patient with a low-placed spinal cord successfully treated by laminotomy: a case report

The authors report a rare case of elderly-onset "lumbar spondylotic myelopathy" occurred on a low-placed spinal cord compressed at multiple levels with thickened ligamenta flava. A posterior decompression surgery could alleviate neurological symptoms successfully instead of untethering of the spinal cord, a widely accepted surgery for tethered cord.

Outcomes of tethered cord repair with a layered soft tissue closure

BACKGROUND

Previous studies have demonstrated the benefit of releasing symptomatic tethered cords; however, complications such as seroma, cerebrospinal fluid leak, and infection continue to plague these patients. We propose that composite tissue closure of tethered cord repairs yields superior outcomes and that a collaborative effort between neurosurgery and plastic surgery may result in enhanced structural and functional results.

METHODS

This is a retrospective study comprised of consecutive patients with tethered cord syndrome by 2 neurosurgeons and 2 plastic surgeons between 1994 and 2008 at a single institution. All consecutive patients who underwent tethered cord release by neurosurgery and subsequent composite tissue closure with fascial and musculofascial flaps by plastic surgery were included. Data were collected by retrospective chart review and analyzed using parametric methods.

RESULTS

A total of 86 consecutive patients were included in this study, with follow-up ranged from 12 to 144 months (average follow-up, 29 months). There were no statistical differences in follow-up time, comorbidities, or surgeon when comparing hospital readmission or reoperation. There was no statistical difference in complications when comparing the different flap closures. We had a 1.2% infection rate, a 4.7% readmission rate, and a 3.5% reoperation rate.

CONCLUSION

We believe that local soft tissue rearrangement improves the closure by providing an additional layer of vascularized tissue between the skin and the spinal cord. We believe our series represents a significant sample size compared with those previously reported for an experience that achieves multilayered soft tissue closure after tethered cord repair. Our results support the idea that neurosurgeons should consider consultation of plastic surgeons when treating patients with tethered cord syndrome surgically.

A comparative study of histopathological analysis of filum terminale in patients with tethered cord syndrome and in normal human fetuses

BACKGROUND

The structural changes in filum terminale (FT) may be responsible for tethered cord syndrome (TCS) in children. Although the histological changes in FT related to TCS are well-known, there is no comparative study of the changes which occur in TCS and normal fetal FT samples. The aims of this study are to compare the histological changes which occurred in FT samples of TCS and in fetuses, and to point out these changes.

METHODS

During the last 2 years, 14 cases of TCS were operated on, the FT was cut and the spinal cord was released. Among them, 6 samples of FT were obtained for histopathological examination. Moreover, 1 FT from an adult cadaver and 4 samples from fetal FT were obtained for the same examination.

RESULTS

While adipose tissue, fibrosis, hyalinization, and meningothelial proliferation were observed in FT samples of TCS, none of these findings were observed in fetal samples. Elastic fibers were present in all TCS specimens and the adult cadaver, but were not observed in fetuses. Peripheral nerves, ganglion cells and ependymal cells were observed in fetal FT samples.

CONCLUSION

These changes probably begin at birth.

Spinal cord traction, vascular compromise, hypoxia, and metabolic derangements in the pathophysiology of tethered cord syndrome

OBJECT

The definition of tethered cord syndrome (TCS) relies mainly on radiological criteria and clinical picture. The presence of a thickened filum terminale and a low-lying conus medullaris in symptomatic patients is indicative of TCS. The radiological definition of TCS does not take into account cases that involve a normal-lying conus medullaris exhibiting symptoms of the disease.

METHODS

The authors performed a MEDLINE search using the terms "tethered cord" and "pathophysiology." The search returned a total of 134 studies. The studies were further filtered to identify mostly basic research studies in animal models or studies related to the biomechanics of the filum terminale and spinal cord.

RESULTS

Spinal cord traction and the loss of filum terminale elasticity are the triggers that start a cascade of events occurring at the metabolic and vascular levels leading to symptoms of the disease. Traction on the caudal cord results in decreased blood flow causing metabolic derangements that culminate in motor, sensory, and urinary neurological deficits. The untethering operation restores blood flow and reverses the clinical picture in most symptomatic cases.

CONCLUSIONS

Although classically defined as a disease of a low-lying conus medullaris, the pathophysiology of TCS is much more complex and is dependent on a structural abnormality, with concomitant altered metabolic and vascular sequelae. Given the complex mechanisms underlying TCS, it is not surprising that the radiological criteria do not adequately address all presentations of the disease.

Tethered cord syndrome in identical twins

The diagnosis of tethered cord syndrome (TCS) without typical conus medullaris symptoms and the radiological features such as a low set conus medullaris or dysraphic malformation is difficult. We report 11 year old identical twin brothers with TCS associated with the conus at the normal level. Their presenting symptom was progressive leg pain and both patients underwent surgical interruption of the filum terminale. The pain recurred in one patient treated surgically only after symptom became worse but resolved immediately in the other sibling treated promptly. We indicate the importance of early diagnosis and treatment of TCS to obtain excellent long-term outcome despite the absence of a low set conus or specific symptoms. Furthermore, when a twin or sibling of an affected person has neurological symptoms and the cutaneous signature of spinal dysraphism, radiological examination should be performed to establish the cause.