Tethered Cord Syndrome with Abnormal Gait
http://www.jabfm.org/cgi/content/full/16/4/345
Maritza DeLaRosa, MD, Vasantha Kondamudi, MD, Noah Kondamudi, MD and Sham Juratli, MD
From the Department of Family Practice (MD, VK, NK, SJ), The Brooklyn Hospital Center, Brooklyn, NY. Address reprint requests to Vasantha Kondamudi, MD, Department of Family Practice, The Brooklyn Hospital Center, Brooklyn, NY 11201
Parents frequently visit their family physicians with concerns of gait abnormality in their children. Minor musculoskeletal anomalies and normal age-related gait variation are the most frequent causes. Tethered cord syndrome is an uncommon pathologic entity that can be initially asymptomatic and subsequently manifest serious neurological sequelae. Prognosis depends on early recognition and prompt surgical correction for optimal outcome. We describe a case of a previously healthy 17-month-old child with abnormal gait who had tethered cord syndrome.
Case Report
A 2-year-old boy was brought to our Family Practice Center with the complaint of abnormal walk for the past 6 months. He had been getting his health maintenance at our center since birth. His great grandmother first expressed concern about the way he walked at age 17 months, but no abnormality was detected at that time. There were no other associated symptoms, including injury, fever, headaches, or weakness.
The prenatal history was remarkable for a maternal second-trimester chlamydial cervicitis that was treated with azithromycin. The child was born at 35 weeks’ gestation by spontaneous vaginal delivery to a 21-year-old mother, para 1,1,1,2. The postnatal period was uncomplicated.
His medical history was notable for a second-degree facial burn at 8 months of age. Social services excluded the possibility of child neglect. He was also evaluated for failure to thrive (height and weight less than 10th percentile) at age 1 year despite apparent good nutrition. At that time there were no serious pathologic findings found on his initial medical workup.
His immunizations were up-to-date, his developmental milestones were normal, and there was no family history of gait or feet abnormalities.
He was a thinly built (height and weight remained at less than the 10th percentile), active child with normal temperature and blood. Respiratory and cardiovascular findings were unremarkable. He had lumbar levoscoliosis, overlapping toes, and increased joint laxity caused by possible hypotonia. He had equal length of both extremities, full range of motion, and good ankle dorsiflexion. There were no sacral dimples, tags, nevi, lipomas, or hypertrichosis. He had normal cranial nerves, normal sensory system, normal power (grade 5), normal tone and reflexes, and good coordination. Genitourinary and rectal findings were normal. His gait was characterized by elevation of the left shoulder and left hip with normal stance and balance. A complete blood count and chemistry profile were normal.
Radiographs of the spine and pelvis showed L4 hemivertebra with sharp levoscoliosis. Spinal magnetic resonance imaging showed low-lying conus medullaris at L3, L4 hemivertebra with associated levoscoliosis. There were no intraspinal masses or lipomas. Findings of a renal sonogram and a voiding cystourethrogram were normal.
The pediatric neurologist confirmed the above findings and noted generalized hypotonia. The chromosomal analysis was normal. Operative findings confirmed a low-lying conus medullaris with stretching of the nerve roots. A thickened fatty filum terminale was also found, which was coagulated and cut, along with release of the tethered spinal cord.
The postoperative course was uneventful and the child at a 1-year follow-up examination had a completely normal gait.
Discussion
Tethered cord syndrome is a broadly used term for progressive neurological deterioration localized to lower spinal cord abnormalities (such as fibrous bands or adhesions, thickened filum terminale, diastematomyelia, or intradural lipoma), resulting in traction on the conus medullaris.1,2
The family physician can see patients with tethered cord syndrome at any age but most often during childhood. Symptoms and signs vary from being asymptomatic to severe lower extremity neurological deficits with bladder and bowel involvement.1 Inspection of the back reveals cutaneous stigmata (sacral dimples, hairy nevus, angiomas, or lipomas) in 70% of cases.3 Children can also have gait abnormalities resulting from scoliosis or asymmetric growth in the foot or leg associated with talipes cavus deformities.4 A few children complain of diffuse pain in lower extremities or urological symptoms4 (recurrent urinary tract infections, enuresis, dribbling, delayed toilet training). In contrast, adults usually complain of diffuse bilateral perianal-perineal pain (86% of cases) and urological symptoms (overflow or stress incontinence).
Skin manifestations are found in 50% cases, but feet deformities are rare.3 The patient might describe a history of urinary tract infections, enuresis, or abnormal micturition, since 20% of the patients will have a neurogenic bladder.5 Our patient did not have the skin stigmata that would have enabled earlier recognition of tethered cord syndrome. The only attributable clinical feature in our patient was levoscoliosis. Scoliosis can be a primary feature of tethered cord syndrome5 in 29% of cases.3 Sensory involvement can manifest as painless trophic skin ulcers in the feet or toes.6 Our patient had no lower limb skeletal or neurological abnormality except for overlapping toes.
Tethered cord refers to the abnormal fixation of the spinal cord observed in patients with dysraphism.2 Prolonged impaired mobility of the spinal cord and nerve roots stretches the spinal cord longitudinally, which potentially compromises the blood supply and causes ischemic damage to the neural tissues.5 Yamada et al7 described two groups of tethered cord patients, one with primary elongation of spinal cord producing excessive tension as described by Hoffman et al,8 and the other with structural lesions (tumors,9-12 myelomeningocele,13 scar formation,14 or a bony spicule15) that result in overstretching or restricting the spinal cord movement. Our patient had the primary tethered cord syndrome as described by Sarwar et al16 in that he was asymptomatic with no associated lower cord anomalies. No urodynamic evaluation was performed for our patient, but when it is performed, it can show detrusor hyperreflexia and bladder-sphincter dysergy.2,17 Our patient had no clinical evidence of bladder or bowel involvement. Loss of bladder or bowel control should trigger a thorough search for detecting spinal cord abnormality.
High incidence of long-tract signs has been observed in patients with diastematomyelia because the septum is located in the mid to high lumbar or thoracic cord.6 Symptoms usually develop gradually, except when initiated by a sudden blow to the back or fall on the buttocks.6 Hyperreflexia associated with motor dysfunction or the Babinski sign can be found in 10% to 17% of patients with tethered cord syndrome.18 Exacerbation of the neurological deficits or deterioration during growth spurts with relative increased cord tethering is typical of this disorder.17
An embryologic developmental defect has long been considered to play a role in spinal cord tethering.19 Barson20 has shown that the conus lies at the level of L1-2 disk by 2 months of age. More rapid growth of the vertebral canal than that of the spinal cord results in the ascension of the spinal cord. This process starts in the 8th to 9th week of fetal age and ceases at the postnatal age of 3 years.21 The cervical cord moves 1.8 to 2.8 cm with the neck flexion and extension. A very active patient with a phase of rapid growth might thus become more symptomatic at an earlier stage.19
Biochemically tethered cord syndrome can be regarded as a metabolic dysfunction of the spinal cord. The steady traction of the neurons causes impairment of the oxidative metabolism that has been shown to improve after surgical untethering.22
Tethered cord syndrome should be considered in the differential diagnosis of patients who have any lower extremity deformities or subtle neurological abnormalities. Any cutaneous sign of occult spinal dysraphism, even in a neurologically intact child, justifies a thorough neurological assessment to facilitate early detection of any upper motor neuron signs. Patients with imperforate anus should be considered for screening for spinal dysraphism, because both conditions can coexist23
The initial evaluation of potential tethered cord should include a thorough neurological examination and appropriate imaging studies. Spina bifida occulta or sacral abnormality is found in 90 of the patients with tethered cord syndrome,24,25 whereas only a few children with incidental radiologic findings of spina bifida occulta have cord tethering.19 Radiographs might show associated vertebral anomalies, such as bifid vertebrae, laminar defects, sacral agenesis, and hemivertebra, in approximately 90% of cases.26 Hemivertebra in our patient was an strong indicator to look for associated spinal anomalies. Spinal dysraphism is the commonest anomaly associated with hemivertebrae and is reported to occur in 15% to 25% of cases.27
Sonography might be helpful in young children for evaluating spinal dysraphism in the absence of spina bifida.28 Magnetic resonance imaging has excellent specificity and sensitivity.29 Urodynamic studies are recommended in most cases of spinal dysraphism.18 The most common imaging and operative finding of tethered cord syndrome are known to be an elongated spinal cord below the L2 level and thick filum terminale (>2 mm).19,28
Management of patients with tethered cord syndrome is controversial. Studies have shown that the potential for reversal of upper motor neuron symptoms can be poor once neurological signs or orthopedics deformities are detected,30 and prophylactic untethering is advocated.7,30 A low-lying conus on imaging studies does not translate into symptoms of tethered cord syndrome, and not all patients with tethered cord actually develop tethered cord syndrome.31 Many neurosurgeons advocate careful follow-up with close surveillance for the development of upper motor neuron signs to determine the need and timing of surgical untethering.2
Surgical intervention in our patient resulted in recovery of his gait, and his neurological status remained completely normal.
Implications
Tethered cord syndrome should be considered in patients with gait disturbance. Its manifestations are subtle and consequences are severe, yet it is eminently treatable. Although most patients evaluated by a family physician have minor musculoskeletal problems, searching for a treatable cause is prudent and rewarding.
Received for publication February 6, 2003. Revision received February 6, 2003.
References
1. Schmidt DM, Robinson B, Jones DA. The tethered spinal cord. Etiology and clinical manifestations. Orthop Rev 1990; 19: 870-6[Medline]
2. Cornette L, Verpoorten C, Lagae L, et al. Tethered cord syndrome in occult spinal dysraphism: timing and outcome of surgical release. Neurology 1998; 50: 1761-5.[Abstract]
3. Pang D, Wilberger JE. Comparison of childhood and adult tethered cord syndrome. J Neurosurg 1982; 57: 40.
4. Haslam R. Tethered cord syndrome. In: Behrman RE, Kliegman RM, Nelson WE, Vaughan VC III, editors. Nelson textbook of pediatrics. 14th ed. Philadelphia: Saunders, 1992: 1536-7.
5. Yamada S, Zinke D, Sanders, D. Pathophysiology of tethered cord syndrome. J Neurosurg 1981; 54: 494-503.[Medline]
6. Tethered spinal cord. Lancet 1986; 2: 549-50.[Medline]
7. Yamada S, Jacono RP, Andrake T, Mandybur G, Yamada BS. Pathophysiology of tethered cord syndrome. Neurosurg Clin N Am April 1995; 311-23.
8. Hoffman HJ, Hendrick EB, Humphreys RP. The tethered spinal cord: its protean manifestations, diagnosis, and surgical correction. Childs Brain 1976; 2: 145-55.[Medline]
9. Bassett RC. The neurologic deficit associated with lipomas of the cauda equine. Ann Surg 1950; 131: 109-16.
10. Naldich TP, McLone DG. Congenital pathology of the spine and the spinal cord. In Tavares JN, Ferrucci JT, editors. Neuroradiology and radiology of the head and neck: diagnosis-imaging-intervention. Philadelphia: JP Lippincott, 1988: 1-28.
11. Rogers HM, Long DM, Chou SN, French LA. Lipomas of the spinal cord and cauda equina. J Neurosurg 1971; 34: 349-54.[Medline]
12. Sokoloff L, Reivich M, Kennedy C, et al. The [14C]deoxyglucose method for the measurement of local cerebral glucose utilization: theory, procedure, and normal values in the conscious and anesthetized albino rat. J Neurochem 1977; 28: 897-916.[Medline]
13. Lassamann LP, James CM. Meningocoele manqué. Childs Brain 1977; 3: 1-11.[Medline]
14. James CM, Lassermann LP. Spinal dysraphism. The diagnosis and treatment of progressive lesions in spina bifida occulta. J Bone Surg 1962; 44: 828-40.
15. Guthkelch AN, Hoffman GT. Tethered spinal cord in association with diastematomyelia. Surg Neurol 1981; 15: 352-4.[Medline]
16. Sarwar M, Virapongse C, Bhimani S. Primary tethered cord syndrome: a new hypothesis of its origin. AJNR Am J Neuroradiol 1984; 5: 235-42.[Abstract]
17. Yamada S. Tethered cord syndrome. In: Pang D, editor. Disorders of the pediatric spine. New York: The Raven Press, 1995; 159-73.
18. Yoneyama T, Fukui J, Ohtsuka K, Komatsu H, Ogawa A. Urinary tract dysfunctions in tethered spinal cord dysfunction: improvement after surgical untethering. J Urol 1985; 133: 999-1001.[Medline]
19. Youmans JR. Neurological surgery: a comprehensive reference guide to the diagnosis and management of neurosurgical problems. Vol 3. Philadelphia: Saunders, 1982: 3: 1237-346.
20. Barson AJ. The vertebral level of termination of the spinal cord during normal and abnormal development. J Anat 1970; 106: 489-97.[Medline]
21. Reimann AF, Anson BJ. Vertebral level of termination of the spinal cord with report of a case of sacral cord. Anat Rec 1944; 88: 127-38.
22. Pang D, Casey K. Use of anal sphincter pressure monitor during operations on the sacral spinal cord and nerve roots. Neurosurgery 1983; 13: 562-8.[Medline]
23. Long FR, Hunter JV, Mahboubi S, Kalmus A, Templeton JM Jr. Tethered cord and associated vertebral anomalies in children and infants with imperforate anus: evaluation with MR imaging and plain radiography. Radiology 1996; 200: 377-82.[Abstract/Free Full Text]
24. Anderson FM. Occult spinal dysraphism: a series of 73 cases. Pediatrics 1975; 55: 826-35.[Abstract/Free Full Text]
25. Fitz CR, Harwood-Nash DC. The tethered conus. Am J Roentgenol Radium Ther Nucl Med 1975; 125: 515-23.[Medline]
26. Warder DE, Oakes WJ. Tethered cord syndrome: the low lying and normally positioned conus. Neurosurgery 1994; 34: 597-600.[Medline]
27. Shahcheragi GH, Hobbi MH. Patterns and progression in congenital scoliosis. J Pediatr Orthop 1999; 19: 766-75.[Medline]
28. Naidich T, Fernbach SK, McLone DG, Shkolnik A. Sonography of the caudal spine and back in congenital abnormalities in children. AJR Roentgenol Am J Radiol 1984; 142: 1229-42.
29. Szelay EA, Roach JW, Smith H, Maravilla K, Partain CL. Magnetic resonance imaging of the spinal cord in spinal dysraphisms. J Pediatr Orthop 1987; 7: 541-5.[Medline]
30. Holtzman RN, Stein BM. The tethered spinal cord. New York: Thieme-Stratton, 1985.
31. Sostrin RD, Thompson JR, Rouhe SA, Hasso AN. Occult spinal dysraphism in the geriatric patients. Radiology 1977; 125: 165-9.[Abstract]
Maritza DeLaRosa, MD, Vasantha Kondamudi, MD, Noah Kondamudi, MD and Sham Juratli, MD
From the Department of Family Practice (MD, VK, NK, SJ), The Brooklyn Hospital Center, Brooklyn, NY. Address reprint requests to Vasantha Kondamudi, MD, Department of Family Practice, The Brooklyn Hospital Center, Brooklyn, NY 11201
Parents frequently visit their family physicians with concerns of gait abnormality in their children. Minor musculoskeletal anomalies and normal age-related gait variation are the most frequent causes. Tethered cord syndrome is an uncommon pathologic entity that can be initially asymptomatic and subsequently manifest serious neurological sequelae. Prognosis depends on early recognition and prompt surgical correction for optimal outcome. We describe a case of a previously healthy 17-month-old child with abnormal gait who had tethered cord syndrome.
Case Report
A 2-year-old boy was brought to our Family Practice Center with the complaint of abnormal walk for the past 6 months. He had been getting his health maintenance at our center since birth. His great grandmother first expressed concern about the way he walked at age 17 months, but no abnormality was detected at that time. There were no other associated symptoms, including injury, fever, headaches, or weakness.
The prenatal history was remarkable for a maternal second-trimester chlamydial cervicitis that was treated with azithromycin. The child was born at 35 weeks’ gestation by spontaneous vaginal delivery to a 21-year-old mother, para 1,1,1,2. The postnatal period was uncomplicated.
His medical history was notable for a second-degree facial burn at 8 months of age. Social services excluded the possibility of child neglect. He was also evaluated for failure to thrive (height and weight less than 10th percentile) at age 1 year despite apparent good nutrition. At that time there were no serious pathologic findings found on his initial medical workup.
His immunizations were up-to-date, his developmental milestones were normal, and there was no family history of gait or feet abnormalities.
He was a thinly built (height and weight remained at less than the 10th percentile), active child with normal temperature and blood. Respiratory and cardiovascular findings were unremarkable. He had lumbar levoscoliosis, overlapping toes, and increased joint laxity caused by possible hypotonia. He had equal length of both extremities, full range of motion, and good ankle dorsiflexion. There were no sacral dimples, tags, nevi, lipomas, or hypertrichosis. He had normal cranial nerves, normal sensory system, normal power (grade 5), normal tone and reflexes, and good coordination. Genitourinary and rectal findings were normal. His gait was characterized by elevation of the left shoulder and left hip with normal stance and balance. A complete blood count and chemistry profile were normal.
Radiographs of the spine and pelvis showed L4 hemivertebra with sharp levoscoliosis. Spinal magnetic resonance imaging showed low-lying conus medullaris at L3, L4 hemivertebra with associated levoscoliosis. There were no intraspinal masses or lipomas. Findings of a renal sonogram and a voiding cystourethrogram were normal.
The pediatric neurologist confirmed the above findings and noted generalized hypotonia. The chromosomal analysis was normal. Operative findings confirmed a low-lying conus medullaris with stretching of the nerve roots. A thickened fatty filum terminale was also found, which was coagulated and cut, along with release of the tethered spinal cord.
The postoperative course was uneventful and the child at a 1-year follow-up examination had a completely normal gait.
Discussion
Tethered cord syndrome is a broadly used term for progressive neurological deterioration localized to lower spinal cord abnormalities (such as fibrous bands or adhesions, thickened filum terminale, diastematomyelia, or intradural lipoma), resulting in traction on the conus medullaris.1,2
The family physician can see patients with tethered cord syndrome at any age but most often during childhood. Symptoms and signs vary from being asymptomatic to severe lower extremity neurological deficits with bladder and bowel involvement.1 Inspection of the back reveals cutaneous stigmata (sacral dimples, hairy nevus, angiomas, or lipomas) in 70% of cases.3 Children can also have gait abnormalities resulting from scoliosis or asymmetric growth in the foot or leg associated with talipes cavus deformities.4 A few children complain of diffuse pain in lower extremities or urological symptoms4 (recurrent urinary tract infections, enuresis, dribbling, delayed toilet training). In contrast, adults usually complain of diffuse bilateral perianal-perineal pain (86% of cases) and urological symptoms (overflow or stress incontinence).
Skin manifestations are found in 50% cases, but feet deformities are rare.3 The patient might describe a history of urinary tract infections, enuresis, or abnormal micturition, since 20% of the patients will have a neurogenic bladder.5 Our patient did not have the skin stigmata that would have enabled earlier recognition of tethered cord syndrome. The only attributable clinical feature in our patient was levoscoliosis. Scoliosis can be a primary feature of tethered cord syndrome5 in 29% of cases.3 Sensory involvement can manifest as painless trophic skin ulcers in the feet or toes.6 Our patient had no lower limb skeletal or neurological abnormality except for overlapping toes.
Tethered cord refers to the abnormal fixation of the spinal cord observed in patients with dysraphism.2 Prolonged impaired mobility of the spinal cord and nerve roots stretches the spinal cord longitudinally, which potentially compromises the blood supply and causes ischemic damage to the neural tissues.5 Yamada et al7 described two groups of tethered cord patients, one with primary elongation of spinal cord producing excessive tension as described by Hoffman et al,8 and the other with structural lesions (tumors,9-12 myelomeningocele,13 scar formation,14 or a bony spicule15) that result in overstretching or restricting the spinal cord movement. Our patient had the primary tethered cord syndrome as described by Sarwar et al16 in that he was asymptomatic with no associated lower cord anomalies. No urodynamic evaluation was performed for our patient, but when it is performed, it can show detrusor hyperreflexia and bladder-sphincter dysergy.2,17 Our patient had no clinical evidence of bladder or bowel involvement. Loss of bladder or bowel control should trigger a thorough search for detecting spinal cord abnormality.
High incidence of long-tract signs has been observed in patients with diastematomyelia because the septum is located in the mid to high lumbar or thoracic cord.6 Symptoms usually develop gradually, except when initiated by a sudden blow to the back or fall on the buttocks.6 Hyperreflexia associated with motor dysfunction or the Babinski sign can be found in 10% to 17% of patients with tethered cord syndrome.18 Exacerbation of the neurological deficits or deterioration during growth spurts with relative increased cord tethering is typical of this disorder.17
An embryologic developmental defect has long been considered to play a role in spinal cord tethering.19 Barson20 has shown that the conus lies at the level of L1-2 disk by 2 months of age. More rapid growth of the vertebral canal than that of the spinal cord results in the ascension of the spinal cord. This process starts in the 8th to 9th week of fetal age and ceases at the postnatal age of 3 years.21 The cervical cord moves 1.8 to 2.8 cm with the neck flexion and extension. A very active patient with a phase of rapid growth might thus become more symptomatic at an earlier stage.19
Biochemically tethered cord syndrome can be regarded as a metabolic dysfunction of the spinal cord. The steady traction of the neurons causes impairment of the oxidative metabolism that has been shown to improve after surgical untethering.22
Tethered cord syndrome should be considered in the differential diagnosis of patients who have any lower extremity deformities or subtle neurological abnormalities. Any cutaneous sign of occult spinal dysraphism, even in a neurologically intact child, justifies a thorough neurological assessment to facilitate early detection of any upper motor neuron signs. Patients with imperforate anus should be considered for screening for spinal dysraphism, because both conditions can coexist23
The initial evaluation of potential tethered cord should include a thorough neurological examination and appropriate imaging studies. Spina bifida occulta or sacral abnormality is found in 90 of the patients with tethered cord syndrome,24,25 whereas only a few children with incidental radiologic findings of spina bifida occulta have cord tethering.19 Radiographs might show associated vertebral anomalies, such as bifid vertebrae, laminar defects, sacral agenesis, and hemivertebra, in approximately 90% of cases.26 Hemivertebra in our patient was an strong indicator to look for associated spinal anomalies. Spinal dysraphism is the commonest anomaly associated with hemivertebrae and is reported to occur in 15% to 25% of cases.27
Sonography might be helpful in young children for evaluating spinal dysraphism in the absence of spina bifida.28 Magnetic resonance imaging has excellent specificity and sensitivity.29 Urodynamic studies are recommended in most cases of spinal dysraphism.18 The most common imaging and operative finding of tethered cord syndrome are known to be an elongated spinal cord below the L2 level and thick filum terminale (>2 mm).19,28
Management of patients with tethered cord syndrome is controversial. Studies have shown that the potential for reversal of upper motor neuron symptoms can be poor once neurological signs or orthopedics deformities are detected,30 and prophylactic untethering is advocated.7,30 A low-lying conus on imaging studies does not translate into symptoms of tethered cord syndrome, and not all patients with tethered cord actually develop tethered cord syndrome.31 Many neurosurgeons advocate careful follow-up with close surveillance for the development of upper motor neuron signs to determine the need and timing of surgical untethering.2
Surgical intervention in our patient resulted in recovery of his gait, and his neurological status remained completely normal.
Implications
Tethered cord syndrome should be considered in patients with gait disturbance. Its manifestations are subtle and consequences are severe, yet it is eminently treatable. Although most patients evaluated by a family physician have minor musculoskeletal problems, searching for a treatable cause is prudent and rewarding.
Received for publication February 6, 2003. Revision received February 6, 2003.
References
1. Schmidt DM, Robinson B, Jones DA. The tethered spinal cord. Etiology and clinical manifestations. Orthop Rev 1990; 19: 870-6[Medline]
2. Cornette L, Verpoorten C, Lagae L, et al. Tethered cord syndrome in occult spinal dysraphism: timing and outcome of surgical release. Neurology 1998; 50: 1761-5.[Abstract]
3. Pang D, Wilberger JE. Comparison of childhood and adult tethered cord syndrome. J Neurosurg 1982; 57: 40.
4. Haslam R. Tethered cord syndrome. In: Behrman RE, Kliegman RM, Nelson WE, Vaughan VC III, editors. Nelson textbook of pediatrics. 14th ed. Philadelphia: Saunders, 1992: 1536-7.
5. Yamada S, Zinke D, Sanders, D. Pathophysiology of tethered cord syndrome. J Neurosurg 1981; 54: 494-503.[Medline]
6. Tethered spinal cord. Lancet 1986; 2: 549-50.[Medline]
7. Yamada S, Jacono RP, Andrake T, Mandybur G, Yamada BS. Pathophysiology of tethered cord syndrome. Neurosurg Clin N Am April 1995; 311-23.
8. Hoffman HJ, Hendrick EB, Humphreys RP. The tethered spinal cord: its protean manifestations, diagnosis, and surgical correction. Childs Brain 1976; 2: 145-55.[Medline]
9. Bassett RC. The neurologic deficit associated with lipomas of the cauda equine. Ann Surg 1950; 131: 109-16.
10. Naldich TP, McLone DG. Congenital pathology of the spine and the spinal cord. In Tavares JN, Ferrucci JT, editors. Neuroradiology and radiology of the head and neck: diagnosis-imaging-intervention. Philadelphia: JP Lippincott, 1988: 1-28.
11. Rogers HM, Long DM, Chou SN, French LA. Lipomas of the spinal cord and cauda equina. J Neurosurg 1971; 34: 349-54.[Medline]
12. Sokoloff L, Reivich M, Kennedy C, et al. The [14C]deoxyglucose method for the measurement of local cerebral glucose utilization: theory, procedure, and normal values in the conscious and anesthetized albino rat. J Neurochem 1977; 28: 897-916.[Medline]
13. Lassamann LP, James CM. Meningocoele manqué. Childs Brain 1977; 3: 1-11.[Medline]
14. James CM, Lassermann LP. Spinal dysraphism. The diagnosis and treatment of progressive lesions in spina bifida occulta. J Bone Surg 1962; 44: 828-40.
15. Guthkelch AN, Hoffman GT. Tethered spinal cord in association with diastematomyelia. Surg Neurol 1981; 15: 352-4.[Medline]
16. Sarwar M, Virapongse C, Bhimani S. Primary tethered cord syndrome: a new hypothesis of its origin. AJNR Am J Neuroradiol 1984; 5: 235-42.[Abstract]
17. Yamada S. Tethered cord syndrome. In: Pang D, editor. Disorders of the pediatric spine. New York: The Raven Press, 1995; 159-73.
18. Yoneyama T, Fukui J, Ohtsuka K, Komatsu H, Ogawa A. Urinary tract dysfunctions in tethered spinal cord dysfunction: improvement after surgical untethering. J Urol 1985; 133: 999-1001.[Medline]
19. Youmans JR. Neurological surgery: a comprehensive reference guide to the diagnosis and management of neurosurgical problems. Vol 3. Philadelphia: Saunders, 1982: 3: 1237-346.
20. Barson AJ. The vertebral level of termination of the spinal cord during normal and abnormal development. J Anat 1970; 106: 489-97.[Medline]
21. Reimann AF, Anson BJ. Vertebral level of termination of the spinal cord with report of a case of sacral cord. Anat Rec 1944; 88: 127-38.
22. Pang D, Casey K. Use of anal sphincter pressure monitor during operations on the sacral spinal cord and nerve roots. Neurosurgery 1983; 13: 562-8.[Medline]
23. Long FR, Hunter JV, Mahboubi S, Kalmus A, Templeton JM Jr. Tethered cord and associated vertebral anomalies in children and infants with imperforate anus: evaluation with MR imaging and plain radiography. Radiology 1996; 200: 377-82.[Abstract/Free Full Text]
24. Anderson FM. Occult spinal dysraphism: a series of 73 cases. Pediatrics 1975; 55: 826-35.[Abstract/Free Full Text]
25. Fitz CR, Harwood-Nash DC. The tethered conus. Am J Roentgenol Radium Ther Nucl Med 1975; 125: 515-23.[Medline]
26. Warder DE, Oakes WJ. Tethered cord syndrome: the low lying and normally positioned conus. Neurosurgery 1994; 34: 597-600.[Medline]
27. Shahcheragi GH, Hobbi MH. Patterns and progression in congenital scoliosis. J Pediatr Orthop 1999; 19: 766-75.[Medline]
28. Naidich T, Fernbach SK, McLone DG, Shkolnik A. Sonography of the caudal spine and back in congenital abnormalities in children. AJR Roentgenol Am J Radiol 1984; 142: 1229-42.
29. Szelay EA, Roach JW, Smith H, Maravilla K, Partain CL. Magnetic resonance imaging of the spinal cord in spinal dysraphisms. J Pediatr Orthop 1987; 7: 541-5.[Medline]
30. Holtzman RN, Stein BM. The tethered spinal cord. New York: Thieme-Stratton, 1985.
31. Sostrin RD, Thompson JR, Rouhe SA, Hasso AN. Occult spinal dysraphism in the geriatric patients. Radiology 1977; 125: 165-9.[Abstract]