Tethered Cord Syndrome (TCS) is a complex of neurologic symptoms that include pain, incontinence, musculoskeletal deformities, motor weakness, and sensory abnormalities resulting from abnormal stretch placed on the distal spinal cord by congenital or acquired factors.1
Primary TCS is associated with abnormal primary or secondary neurulation during spinal cord development. This can result in conditions such as myelomeningocele, split cord malformations, thickened filum terminale, and lumbosacral lipomas that may lead to TCS. Secondary TCS can occur in the setting of normal development following infection, surgery, trauma, irradiation, or tumor.2 In one series, secondary TCS was identified in as many as 30% of children who underwent surgery for primary spinal dysraphism.3
Epidemiology including risk factors and primary prevention
The true incidence of TCS is unknown. Due to folic acid supplementation during pregnancy and in our food supply, the number of people born with open neural tube defects and subtle errors of neurulation has decreased. In contrast, the diagnosis of closed or occult spinal dysraphism has risen steadily due to the incidental detection by MRI imaging and greater clinical awareness.3
Primary TCS may be caused by any number of anomalies during development. Primary canalization, or folding of the neural plate to form the neural tube, occurs around gestational days 18-28. This process starts at the midpoint of the spine and proceeds in both caudal and rostral directions. Abnormalities may develop if this process fails to complete, or if nearby mesenchymal cells invade the neural groove before complete fusion takes place. This can result in both myelomeningocele and other open neural tube defects, as well as the development of hamartomas or non-cancerous abnormal cell masses such as lipomas. Secondary neurulation defects may occur during canalization and fusion of the caudal cell mass (days 43-48) and result in split cord malformations or development of an abnormal filum terminale.5-7
The filum is a viscoelastic band that allows the conus medullaris to move during flexion and extension of the spine. It is believed that if the viscoelasticity of the filum is lost or compromised by fatty infiltration or abnormal thickening, then caudal tension and traction may cause undue stress upon the conus, resulting in TCS.3 The most distal two thirds of the filum terminale consists of a specific ratio of elastic and collagen proteins that has been shown to be abnormal in multiple studies that compare the structure of the filum from TCS patients to that obtained from control subjects. The filum from TCS patients also shows increased adipose, fibrosis, and loss of typical cell architecture.5
The dysfunction seen in TCS involves the gray matter of the distal cord and causes impairment of oxidative metabolism1 This impairment mimics the changes seen in hypoxic injuries to the spinal cord, and in fact, Yamada et al showed increased blood flow to the distal spinal cord after sectioning of the filum in TCS patients. While mild to moderate stretch is associated with transient decreases in metabolism, more prolonged stretch may lead to cell wall and mitochondrial membrane damage.5
Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)
The presentation of TCS can be highly variable from individual to individual due to the heterogeneity in underlying cause and differences in condition severity. Roughly 38.7 of every 100,000 births in the United States result in a diagnosis of TCS that can be identified in infancy due to cutaneous manifestations or associated structural or anorectal abnormalities.9 In later childhood and adulthood, pain and urinary symptoms tend to dominate the presentation.7
In recent years, the presence or absence of a clinical entity known as occult tethered cord syndrome has been widely debated. Proponents of this syndrome report patients with abnormal UDS but magnetic resonance imaging (MRI) that shows a normal conus position, sometimes with a thickened or fatty filum. A number of studies have been published that show surgical intervention may improve urinary symptoms in 60-97% of these children.3,5,13 However, these studies have been small, had no control arm, and had inconsistent or absent urodynamic data. A 2015 randomized controlled pilot study by Steinbok et al showed no difference between surgical and medically managed patients, but was underpowered to detect clinical significance and reported on only severe cases who had been symptomatic for approximately 5 years at time of surgical intervention.
Disease progression over time is widely variable due to the underlying etiology of tethering. Unfortunately, more research needs to be done to look at the rate of progression. It is clear that some patients do have a relatively benign course and as many as 20% in some series may even improve without surgical treatment.5,13 However, Pang et al demonstrated a 30-40% progression rate over 10 years for asymptomatic individuals with TCS due to lipoma. Even after surgical detethering, patients remain at risk for retethering and progression of symptoms. Some studies with partial lipoma resection show this to be as high as 65% of all patients.6
Specific secondary or associated conditions and complications
Urinary incontinence tends to be one of the two most common symptoms of TCS, and other urinary dysfunction such as over or underactive bladder, change in bladder capacity, increased post void residual volumes, decreased bladder compliance, and detrusor-sphincter dyssynergia have all been reported in the literature. Urodynamic study (UDS) is the most reliable method to evaluate these abnormalities. Meyrat et al proposed a scoring system for urodynamic performance that has been validated by Kim et al that shows that UDS score at 6 months after spinal cord untethering surgery may be a good long-term predictor of bladder dysfunction.10-12
Pain also tends to be a common complaint amongst children and adults with TCS. This pain tends to occur in either the low back, perineal region, or in a nondermatomal distribution in the lower extremities. It has been described as constant and intense, frequently worsened with flexion/extension activities of the spine. In addition, the pain can be new in onset after a direct traumatic injury to the spinal cord, pregnancy, or exercise.7,14
Orthopedic deformities may also occur along with TCS. Scoliosis is a common finding in greater than 10% of patients. Curvature may be present at birth, but in 2016 Barutcuoglu et al reported on a series of 18 patients, many of whom presented with late-onset left sided thoracic curvature (average Cobb angle 31.6) and compensatory lumbar curve (Barutcuoglu). Review of the national Kids’ Inpatient Database, which tracks 7.4 million pediatric hospital admissions across the country between 2000-2009, showed co-occurring scoliosis in 16.7% of patients undergoing surgery for TCS.16 Other orthopedic deformities commonly reported include leg length deformity and foot deformities.
Other symptoms that may be reported with TCS include neurogenic bowel dysfunction of varying degrees, leg numbness and weakness, and changes in tone with both hyporeflexia and decreased tone and hyperreflexia with spasticity being reported. Adults may also report sexual dysfunction.7
TCS has been linked to several associated congenital abnormalities including:
- Cutaneous manifestations
- Hairy patch
- Lumbosacral mass
- Caudal tail
- Orthopedic/vertebral abnormalities
- Anorectal/urogenital malformations
- Omphalocele, exstrophy, imperforate anus, spinal defect [OEIS]
- Vertebral defect, anal defect, tracheo-esophageal defect, renal defect [VATER]2
There have also been some reports of Chiari malformation associated with TCS, suggesting a yet unexplained genetic etiology.17
Complications associated with TCS vary based on the underlying clinical presentation, but may include urinary tract infection (UTI) due to urologic dysfunction, skin breakdown due to insensate skin, gait abnormalities, progressive pain, worsening scoliosis, and even syrinx development adjacent to the caudal attachment to the filum terminale.14
2. ESSENTIALS OF ASSESSMENT
The clinician obtains a prenatal, birth, and postnatal history and questions the patient about any back or leg pain, urine or bowel incontinence, sensory or motor change. The pain is often characterized as being constant, intractable, and aggravated by movement. Sensory loss is usually patchy and does not follow a dermatomal pattern. Motor weakness may be subtle and in only one muscle group. The patient may have a history of increased falls, decreased endurance, or decreased ambulation distance.
A past medical history should include questions of any orthopedic deformities (hemivertebrae, leg length discrepancy, pes cavus, equinus deformity), scoliosis, and toe walking.
A family history of first- and second-degree relatives is taken to determine if there is a genetic pattern.
The patient’s spine is observed and palpated for abnormalities and scoliosis. The lumbosacral spine and coccygeal area are inspected for cutaneous manifestations (hairy patch, hemangioma, dimple, lumbosacral mass, or caudal tail). A thorough neurologic examination consisting of sensory (pinprick and light touch at each dermatome) and motor examinations (manual motor testing), deep tendon reflexes, and gait assessment is obtained. The clinician examines feet for pes cavus and equinus deformities and the legs for leg length discrepancies and spasticity.
Sensory loss tends to be in a nonsegmental distribution. Variable deep tendon reflexes and tone are found. There may be asymmetric motor weakness and atrophy. The clinician should compare previous examinations if possible.
A functional history is taken to determine a decrease in independence or new use of an assistive device. Prior function previous to onset of symptoms is asked, with focus on transfers and mobility.
In children, achievement of developmental milestones (independence with sitting, standing, walking, and toilet training) are asked. Inquiries should also be made about any possible loss of milestones previously attained.
Radiographic findings must always be taken in context with the clinical symptoms when making the diagnosis of TCS, but a number of different imaging modalities may be utilized to help with evaluation and surgical planning.
Scoliosis films may be used to detect progression in the cobb angle as a symptom of tethered cord syndrome.
A plain spine x-ray can be helpful to detect spina bifida occulta.
MRI is the current gold standard for diagnosis. The images usually show a low-lying cord below the level of L1-2 and a thickened filum terminale with a diameter greater than 2mm.5 Some authors have also recommended proceeding to prone MRI in cases of high suspicion with negative supine MRI findings. It is postulated that a tethered cord will be identified in a more posterior position using this technique. However, even using this technique, sensitivity may be as low as 62% and interrater reliability as low as 69%.5
If the patient has had previous surgery for a spinal dysraphism, the area of scar will show a tethered cord. Once again, the clinician must look at the constellation of presenting symptoms and correlate them with radiographic findings. Thus, MRI is used for planning of surgery rather than diagnosis in most cases with prior known surgical intervention due to spinal dysraphism. But the clinician must rule out other causes for the neurological symptoms, such as syrinx, herniated nucleus pulposus, infection, tumor, etc. CT scans are also frequently obtained for better bony imaging and surgical planning.
Due to the absence of a bony arch in spina bifida patients and the lack of lumbar ossification, ultrasound may be used in infants of less than 4-5 months to prevent exposure to radiation and sedation.10 In one series of infants presenting with anorectal malformation, the sensitivity and specificity of ultrasound compared to MRI was as high as 80% and 89%, respectively. This yielded a negative predictive value as high as 97%, but a positive predictive value of only 47%. As such, it is recommended that symptomatic children screened by ultrasound in infancy have an MRI later on in life.18
Supplemental assessment tools
Urodynamic studies diagnose urologic dysfunction or detect worsening of dysfunction. The urodynamic studies show abnormalities before clinical urologic symptoms appear. These abnormalities include: hyperreflexia, external detrusor-sphincter dyssynergia, decreased sensation, decreased compliance, and hypocontractile detrusor.6
As mentioned previously, Meyrat et al has published an objective, validated UDS scale for use in children with tethered cord syndrome. The scale looks at bladder volume, expressed as percentage of predicted and graded on a 0 (normal) to 5 (<20% predicted) scale; compliance graded on a 0 (>25% or normal) to 4 (<10%) scale; detrusor activity on a 0 to 5 scale; and vesico-sphincter synergy on a 0 to 3 scale; for a maximum score of 17, with larger score being more abnormal. Children in the control group showed a score of 3.5 ± 2.1 compared to 8.9 ± 4.7 in the case mix.11 Kim et al showed that the scores at 6 months following surgery were predictive of urologic outcomes for at least 2 years following surgery.
In only the last few years, routine neurophysiologic monitoring utilized during tethered cord surgeries in Canada have led to another possible supplemental assessment tool. TCS patients, when compared to controls undergoing spinal surgery for scoliosis, tend to have a prolonged P37 peak in their somatosensory evoked potentials (SSEP). The P37 peak represents the arrival of sensory information from the limb to the somatosensory cortex. Similar prolongation has been noted previously in demyelinating lesions, such as multiple sclerosis. TCS patients had an average peak P37 prolongation of 17.2 ± 0.65 msec vs 14.8 ± 1.3 msec in controls, and following cord detethering showed an immediate shift toward the normal range of 16.1 ± 0.52 msec.19
Early predictions of outcomes
There is not much data on TCS outcomes. Lew et al. reported the rate of retethering in surgical series to be 5-50%.7 However, these percentages may not be generalizable. The risk of retethering decreases after adult stature is reached and growth has stopped, and may also be dependent upon surgical technique used.6
The physiatrist asks if help is needed within the home to maintain the patient’s independence or to help care for the patient. Questions about stairs and access at home and school are asked if mobility has changed.
Social role and social support system
Social support systems are an important aspect of dealing with new disabilities after TCS. Support groups through the Spina Bifida Association of America target those with congenital spinal dysraphisms.
3. REHABILITATION MANAGEMENT AND TREATMENTS
Available or current treatment guidelines
There are no established practice guidelines in the literature.
At different disease stages
Therapy and pain management may be tried before surgery if the patient does not have neurological symptoms. Patients with low back pain and leg pain may benefit from therapy that does not focus on flexion to the spine. Aquatherapy is a good start for patients. It eliminates gravity and gradual resistance may be added to build endurance and strength. Pain management techniques including medications typically used for neuropathic pain, opiates, intrathecal pain pumps, and spinal cord stimulators have been used.
Patients should also be queried and monitored for bowel and bladder dysfunction. These may be managed in typical fashion for neurogenic bowel and bladder. Rehabilitation physicians may help direct use of laxatives, stool softeners, and suppositories for neurogenic bowel regimens. For the neurogenic bladder, use of timed voids, catheterization, chemodenervation, or pharmacologic use of alpha blockers, beta3 adrenergic blockers, tricyclic antidepressants, or anticholinergics may be used depending on the individual dysfunction. Urologic consultation may be warranted.
Surgical repair with tethered cord release is done for patients with neurological symptoms to improve or stabilize the symptoms. During the tethered cord release, neurological monitoring of the lower sacral nerve roots and spinal cord are done through the use of somatosensory evoked potentials (SSEP) and electromyography. However, surgery is not without risk. Complication rates in the literature average approximately 7.2% of cases, and occur more frequently in children over the age of 10. The most common types of complication encountered after tethered cord release surgery are leakage of cerebrospinal fluid (CSF), urinary tract infections, pulmonary complications, and neurologic deterioration.16 Every surgical procedure has a risk of retethering that may be dependent on surgical technique and underlying etiology, and it has been suggested that likelihood of symptom improvement is also dependent on these factors .16,20 A detailed discussion with the neurosurgeon is done prior to surgical intervention.
In TCS, physiatrists are involved in identification and management. Once tethered cord release is performed, patients are evaluated by physiatry to identify new deficits and recommend treatment. At times, patients do have worsening deficits and should be evaluated for inpatient rehabilitation to provide a comprehensive team approach towards their recovery.
A urologic evaluation should be performed to determine if the patient has new or changed neurogenic bladder symptoms. Neurogenic bowel function is assessed and bowel program begun based on individual needs. Patients should be placed on bowel medications that decrease the need for intense Valsalva maneuvers. Family and/or a designated caregiver learns the bowel and bladder management. It is not until adolescence and adulthood that the patient is also independently trained.
Patients and family must be educated on skin integrity and the need for frequent weight shifts. For those patients who have new sensory deficits in the perineal area, a sitting program will be initiated to prevent skin breakdown. The sitting program consists of gradually increasing daily sitting time to train the newly insensate skin to accept pressure.
A patient’s mobility may be affected to the degree that new assistive devices may be required, or a wheelchair and cushion evaluation may be necessary.
Coordination of care
TCS is best identified and managed within the multidisciplinary clinic setting. The team consists of physiatry, neurosurgery, urology, orthopedic surgery, nursing, social work, and physical therapy.
Patient & family education
Education depends on the extent of deficits with TCS. The patient and family will be educated on neurogenic bowel and bladder management and prevention of skin breakdown. The signs and symptoms of retethering (pain, sensory loss, muscle weakness, changes in bowel or bladder habits) are also taught so that the patient and family may recognize the symptom complex and seek evaluation promptly.
There are no specific standardized outcome measures for TCS.
Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills
Many times, subtle findings such as foot deformities or abnormalities of gait may clue the physician into the diagnosis of tethered cord syndrome.
New onset pain or bowel and bladder difficulties in a growing child or an adult after trauma or pregnancy should prompt consideration of TCS.
Additionally, tethered cord syndrome is an important differential consideration in atypical pain presentations that are not dermatomal in origin.
4. CUTTING EDGE/EMERGING AND UNIQUE CONCEPTS AND PRACTICE
5. GAPS IN THE EVIDENCE-BASED KNOWLEDGE
Gaps in the evidence-based knowledge
The gaps in evidence-based knowledge include the true incidence of TCS, genetic predeterminence, timing of surgical intervention in symptomatic and asymptomatic patients, and lack of outcome studies.
- Huang S-L, Peng J, Yuan G-L, Ding X-Y, He X-J, Lan B-S. A new model of tethered cord syndrome produced by slow traction. Sci Rep. 2015;5:9116. doi:10.1038/srep09116.
- Agarwalla PK, Dunn IF, Scott RM, Smith ER. Tethered cord syndrome. Neurosurg Clin N Am. 2007;18(3):531-547. doi:10.1016/j.nec.2007.04.001.
- Geyik M, Geyik S, Şen H, et al. Urodynamic outcomes of detethering in children: experience with 46 pediatric patients. Childs Nerv Syst. March 2016. doi:10.1007/s00381-016-3053-y.
- Bui CJ, Tubbs RS, Oakes WJ. Tethered cord syndrome in children: a review. Neurosurg Focus. 2007;23(2):E2. doi:10.3171/foc.2007.23.2.2.
- Tu A, Steinbok P. Occult tethered cord syndrome: a review. Childs Nerv Syst. 2013;29(9):1635-1640. doi:10.1007/s00381-013-2129-1.
- Pang D, Zovickian J, Wong S-T, Hou YJ, Moes GS. Surgical treatment of complex spinal cord lipomas. Childs Nerv Syst. 2013;29(9):1485-1513. doi:10.1007/s00381-013-2187-4.
- Hertzler DA, DePowell JJ, Stevenson CB, Mangano FT. Tethered cord syndrome: a review of the literature from embryology to adult presentation. Neurosurg Focus. 2010;29(1):E1. doi:10.3171/2010.3.FOCUS1079.
- Yamada S, et al. Pathophysiology of Tethered cord syndrome and similar complex disorders. Neurosurg Focus 2007; 23: E6 1-10.
- Callie A. M. Atta, et al. Global birth prevalence of spina bifida by folic acid fortification status: A systematic review and meta-analysis. American Journal of Public Health. 2016; 106: 1(e24-e34).
- Geyik M, Alptekin M, Erkutlu I, et al. Tethered cord syndrome in children: a single-center experience with 162 patients. Childs Nerv Syst. 2015;31(9):1559-1563. doi:10.1007/s00381-015-2748-9.
- Meyrat BJ, Tercier S, Lutz N, Rilliet B, Forcada-Guex M, Vernet O. Introduction of a urodynamic score to detect pre- and postoperative neurological deficits in children with a primary tethered cord. Childs Nerv Syst. 2003;19(10-11):716-721. doi:10.1007/s00381-003-0829-7.
- Kim SW, Ha JY, Lee YS, Lee HY, Im YJ, Han SW. Six-month postoperative urodynamic score: a potential predictor of long-term bladder function after detethering surgery in patients with tethered cord syndrome. J Urol. 2014;192(1):221-227. doi:10.1016/j.juro.2014.02.2549.
- Steinbok P, MacNeily AE, Hengel AR, et al. Filum section for urinary incontinence in children with occult tethered cord syndrome: A randomized, controlled pilot study. J Urol. 2016;195(4P2):1183-1188. doi:10.1016/j.juro.2015.09.082.
- Klekamp J. Tethered cord syndrome in adults. J Neurosurg Spine. 2011;15(3):258-270. doi:10.3171/2011.4.SPINE10504.
- Barutçuoğlu M, Selçuki M, Umur AS, Mete M, Gurgen SG, Selcuki D. Scoliosis may be the first symptom of the tethered spinal cord. Indian J Orthop. 2016;50(1):80-86. doi:10.4103/0019-5413.173506.
- Shweikeh F, Al-Khouja L, Nuño M, Johnson JP, Drazin D, Adamo MA. Disparities in clinical and economic outcomes in children and adolescents following surgery for tethered cord syndrome in the United States. J Neurosurg Pediatr. 2015;15(4):427-433. doi:10.3171/2014.9.PEDS14241.
- Glenn C, Cheema AA, Safavi-Abbasi S, Gross NL, Martin MD, Mapstone TB. Spinal cord detethering in children with tethered cord syndrome and Chiari type 1 malformations. J Clin Neurosci. 2015;22(11):1749-1752. doi:10.1016/j.jocn.2015.05.023.
- van den Hondel D, Sloots C, de Jong THR, Lequin M, Wijnen R. Screening and treatment of tethered spinal cord in anorectal malformation patients. Eur J Pediatr. Surg. Off. J. Austrian Assoc. Pediatr. Surg. [et al] = Zeitschrift für Kinderchirurgie. 2016;26(1):22-28. doi:10.1055/s-0035-1563673.
- Leung V, Pugh J, Norton JA. Utility of neurophysiology in the diagnosis of tethered cord syndrome. J Neurosurg Pediatr. 2015;15(4):434-437. doi:10.3171/2014.10.PEDS1434.
- Goodrich DJ, Patel D, Loukas M, Tubbs RS, Oakes WJ. Symptomatic retethering of the spinal cord in postoperative lipomyelomeningocele patients: a meta-analysis. Childs Nerv Syst. 2016;32(1):121-126. doi:10.1007/s00381-015-2839-7.
- Filippidis AS, Kalani MY, Theodore N, Rekate HL. Spinal cord traction, vascular compromise, hypoxia, and metabolic derangements in the pathophysiology of tethered cord syndrome. Neurosurg Focus. 2010;29(1):E9. doi:10.3171/2010.3.FOCUS1085.
- Giddens JL, Radomski SB, Hirshberg ED, Hassouna M, Fehlings M. Urodynamic findings in adults with the tethered cord syndrome. J Urol. 1999;161(4):1249-1254. http://www.ncbi.nlm.nih.gov/pubmed/10081879. Accessed April 11, 2016.
- Lew SM, Kothbauer KF. Tethered cord syndrome: an updated review. Pediatr Neurosurg. 2007;43(3):236-248. doi:10.1159/000098836.
Original Version of the Topic:
Stacy M. Stark, DO. Tethered Cord Syndrome. Publication Date:2012/08/07
Rajashree Srinivasan, MD
Nothing to Disclose
Angela Vrooman, DO
Nothing to Disclose