Tethered cord syndrome: A study of 35 patients

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier’s archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright Author's personal copy Journal of Taibah University Medical Sciences (2012) 7(1), 23–28 Taibah University Journal of Taibah University Medical Sciences www.jtaibahunimedsc.net www.sciencedirect.com Clinical Study Tethered cord syndrome: A study of 35 patients Khalid I. Khoshhal, ABOS a, Waleed R. Murshid, FRCS (SN) b,*, Essam A. Elgamal, FRCS (SN) c, Mustafa A.M. Salih, M.D d a Department of Orthopedics, College of Medicine, Taibah University, Almadinah Almunawwarah, Saudi Arabia Department of Surgery, College of Medicine, Taibah University, Almadinah Almunawwarah, Saudi Arabia c Division of Neurosurgery, Department of Surgery, College of Medicine, King Saud University, Riyadh, Saudi Arabia d Division of Pediatric Neurology, Department of Pediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia b Received 7 May 2012; revised 21 June 2012; accepted 30 June 2012 KEYWORDS Child; Neural tube defect; Presentation; Spinal dysraphism; Saudi Arabia; Tethered cord syndrome Abstract Objectives: Tethered cord syndrome (TCS) is a stretch-induced functional disorder of the spinal cord in which the caudal part is anchored by an inelastic structure. The majority of cases are related to spinal dysraphism. The presentations differ according to the underlying pathological condition and age, with pain, cutaneous signs, orthopedic deformities and neurological deficits being the commonest. Our aim was to determine the presentations in Saudi patients and to study the natural history of untreated late presenting cases. Methods: This was a retrospective study of 35 consecutive Saudi patients with TCS seen at a single institution over a period of 7 years. The frequency and presentation of each type of spinal dysraphism and the natural history of untreated, late-presenting cases were studied. Results: The most frequent spinal dysraphism associated with TCS was lipomeningomyelocele in 12 patients (34.3%), followed by TCS secondary to myelomeningocele in 8 patients (22.8%). Dermal sinus was found in 5 patients, diastematomyelia in 4 patients, meningocele in 3 patients and thick filum terminale in 3 patients. Thirteen patients out of 19 patients over 2 years of age (68.4%), presented with progressive neurological deficits. Conclusion: Patients suspected of having TCS must be referred and treated by the age of 2 years, or soon after diagnosis, as they are likely to develop progressive neurological deficits if untreated. Normal radiology in the presence of clinical features of cord tethering should not exclude the diagnosis of TCS. ª 2012 Taibah University. Production and hosting by Elsevier Ltd. All rights reserved. * Corresponding author. Address: Professor of Neurosurgery, Consultant Neurosurgeon, College of Medicine, Taibah University, Almadinah Almunawwarah, Saudi Arabia. E-mail address: [email protected] (W.R. Murshid). Peer review under responsibility of Taibah University. Production and hosting by Elsevier Introduction Tethered cord syndrome (TCS) is an increasingly recognized clinical disorder, which is usually identified in childhood and is defined as a stretch-induced functional disorder of the spinal cord with its caudal part anchored by an inelastic structure.1–3 The disproportionate longitudinal growth between the vertebral column and the tethered spinal cord results in stretching of the conus medullaris and nerve roots. The accepted cause 1658-3612 ª 2012 Taibah University. Production and hosting by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jtumed.2012.07.005 Author's personal copy 24 K.I. Khoshhal et al. of TCS is spinal cord traction, which leads to anatomic and metabolic disorders that are responsible for the clinical presentation.4 Fixation of the spinal cord can occur congenitally (primary TCS) or in association with other intraspinal pathologies or postoperative scarring (secondary TCS).5 Most cases are related to spinal dysraphism. The age at presentation of TCS ranges from early childhood to the 80s.6 The symptoms related to a congenital tethered cord occur most commonly in childhood, but in many patients, the diagnosis is not established until adulthood.2 The presentation may also differ according to the underlying pathology, with back and leg pain, cutaneous signs, orthopedic deformities, muscle weakness, urinary dysfunction and neurological deficits being the most common.7–10 Other manifestations include gait deterioration, foot deformities, progressive scoliosis, and sphincter incontinence.11 Young children may have skeletal growth deformities, such as a leg-length discrepancy. Adolescent or young adult patients often complain of unexplained long-term back pain.12–14 The findings at physical examination may be unimpressive or include a combination of lower and upper motor neuron abnormalities, in addition to one or more of the cutaneous signs associated with occult spinal dysraphism, such as an abnormal tuft of hair in the lumbosacral area (‘fawn tail’), fatty masses associated with lipomeningomyelocele or perhaps deep dimples or sinus tracts, or small angiomatous-appearing birthmarks in the mid-lumbar area.15 The diagnosis can be difficult due to the subtleness of the signs and symptoms, which may be easily overlooked.8 Spinal ultrasound in neonates and magnetic resonance imaging (MRI) in older children allow ready diagnosis of TCS and will almost always reveal the cause.13,15 In infants, a high-resolution ultrasound examination can also be a good screening test. Radiological abnormalities such as low lying conus medullaris, lumbosacral lipoma, filum terminale lipoma, or thick filum terminale are the keys for the diagnosis of TCS.16 Surgical untethering should be considered upon appearance of upper motor neuron signs or progression of lower motor neuron signs. In cases of myelomeningocele, low-lying conus is commonly seen without clinical evidence of cord tethering; therefore, radiographic imaging cannot be the sole basis for the diagnosis.11 At the same time, normal radiology should not exclude TCS. In general, to avoid irreversibility, prompt diagnosis and surgical untethering must be done in patients who have the greatest chance of restoration of neurological function and return to their optimal occupational capacities.14,17 The aim of this study was to shed some light on the natural history of TCS, and to determine the common presentation of TCS in Saudi Arabia where many of the patients present later than those seen in industrialized countries. The other aim was to improve awareness, between those who take care of susceptible patients like neurosurgeons, orthopedics, urologist and pediatricians so that patients are referred for the definitive care earlier, for a much better long-term outcome of the treatment.18 Materials and methods We conducted a retrospective study of 35 consecutive Saudi patients with TCS who were seen and managed at King Khalid University Hospital, College of Medicine, King Saud University, Riyadh, Saudi Arabia, over a period of 7 years (1997– 2003). Patients with primary myelomeningocele were excluded. The frequency and presentation of each type of spinal dysra- Figure 1: MRI, T2-weighted image (A), and T1-weighted image (B) of a patient with lipomyelomeningocele of the lower lumbar region, showing a low-lying cord at the level of L3-L4 with spina bifida involving lower lumbar and sacral spine. Note intra- and extra-spinal lipoma (arrow). Author's personal copy Tethered cord syndrome: A study of 35 patients Table 1: Types of spinal dysraphism associated with tethered cord syndrome (TSC). Type of spinal dysraphism No. of patients Percentage Lipomyelomeningocele 12 TCS secondary to myelomeningocele 8 Dermal Sinus 5 Diastematomyelia 4 Thick filum terminale 3 Meningocele 3 Total 35 34.3 22.8 14.3 11.4 8.6 8.6 25 had progressive lower limb weakness and the other three presented with difficulty in walking. The patients with diastematomyelia (Figure 2) had mild symptoms, and TCS was diagnosed in three of them when they were less than 6 months of age (Table 2). One of the three patients with thick filum terminale (Figure 3) presented with progressive symptoms at the age of 4 years, and three of the eight patients with dermal sinus manifested severe symptoms at, or after, the age of 2 years. Discussion 100 phism and the natural history of untreated late presenting cases were studied for the progression of signs and symptoms. Results A total of 35 patients with TCS were included with 16 males and 19 females, giving a ratio of 1:1.2. The patients’ ages ranged from 2 months to 11 years (mean, 2.96 years), with one patient outside this range, presenting at the age of 43 years. The most frequent spinal dysraphism associated with TCS was lipomeningomyelocele (Figure 1) in 12 patients (34.3%). The other types of spinal dysraphism that were associated with TCS in the current study are listed in Table 1. Progressive neurological deficits were seen in 13 out of 19 patients (68.4%) aged 2 years or older. Of the 12 patients with lipomeningomyelocele, eight (66.7%) presented with a lump on the back, and four patients (33.3%) with progressive neurological deterioration. Six of the eight (75%) patients with TCS secondary to myelomeningocele presented with neurogenic bladder; three The term ‘filum terminale syndrome’ was first used by Garceau in 1953 in describing three patients.19 Two decades later, in 1976, Hoffman and colleagues coined the term ‘tethered spinal cord’ to describe the symptoms of their patients with an elongated spinal cord and a thick filum terminale.20 Yamada et al.4 in 1981 broadened the stretch-induced functional disorder to include patients with other anomalies, such as myelomeningocele, lipoma, lipomeningomyelocele, diastematomyelia, meningocele, and dermoid sinus. Recently, Yamada and Won2 described three categories of TCS. The first was lumbosacral cord anchored by an inelastic filum, and the second category included caudal as well as many sacral myelomeningoceles. The third category was divided into two groups; the first was paraplegia associated with lipomeningomyelocele and myelomeningocele, apparently with no functional lumbosacral neurons. No neurologic benefit is expected from surgery in this group. The second group included asymptomatic patients with an elongated cord and a thick filum. These patients require close observation for subtle symptoms, particularly incontinence, which if untreated might quickly become irreversible. Figure 2: (A) MRI T2-weighted image showing a low-lying cord and a diastematomyelia (arrow). (B) Computerized tomography, axial view showing the bony diastematomyelia, and spina bifida (arrow). Author's personal copy 26 K.I. Khoshhal et al. Table 2: Clinical presentation of tethered cord syndrome in different conditions.a Presentation Lipomyelomeningocele Back lump Kyphoscoliosis Back and leg pain Back tenderness Lower limb weakness Nocturnal enuresis Fecal incontinence Myelomeningocele Hydrocephalus Neurogenic bladder Lower limb weakness Back pain Walking difficulty Pressure sores <2 years 8 1 1 1 1 2 3 1 3 2 2 1 3 1 1 1 1 1 1 2 Diastematomyelia Tuft of hair Gibbus Neurogenic bladder Back scar 2 1 1 Meningocele Meningocele Kyphosis Renal anomalies Lower limbs deformity Urinary incontinence Tuft of hair UMN manifestations >8 years 1 1 1 Dermal sinus Subcutaneous abscess Meningitis Back pain and tenderness Walking difficulty Urine incontinence UMN manifestations Thick filum terminale Kyphosis Imperforate anus Horseshoe kidney Urinary incontinence Walking difficulty 2–8 years 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Total % 12 10 1 1 1 1 1 1 100 83 8.3 8.3 8.3 8.3 8.3 8.3 8 5 6 3 1 3 1 100 62.5 75 37.5 12.5 37.5 12.5 5 1 2 1 1 3 1 100 20 40 20 20 60 20 4 2 1 1 1 100 50 25 25 25 3 2 100 66.6 33.3 33.3 33.3 33.3 3 1 1 1b 1b 1b 1b 1b 100 33.3 33.3 33.3 33.3 33.31 33.3 33.3 Abbreviations: UMN, upper motor neuron. a More than one clinical presentation may be present in the same patient. b This patient was 43 years old. The most frequent spinal dysraphism associated with TCS in this study was lipomeningomyelocele (34.3%), followed by TCS secondary to myelomeningocele, which constituted 22.8% of cases and was more prevalent than the 3–15% reported in the literature.21,22 The presenting symptoms in this series were similar to those described by Herman et al.12: weakness, deterioration in gait, scoliosis, orthopedic deformities, and urinary incontinence. It has also been recommended that any infant with a mid-line lumbar cutaneous abnormality, such as a hemangioma, lipoma, hair patch or dimple, be evaluated to rule out tethering of the spinal cord.13 The slow rate of clinical deterioration usually contributes to the delayed recognition of TCS in patients with myelomeningocele. The preexisting neurological impairments also make subtle neurological changes difficult to detect. Detailed neurological, orthopedic and urological (urodynamic studies) examination and a heightened awareness of the possibility of tethered cord will lead to earlier detection. Therefore, patients should be followed-up by a multidisciplinary team consisting of specialists from neurosurgery, orthopedic surgery and urology. It is a misconception that myelomeningocele is a static lesion and that active problems are confined to childhood. The inherent complications require early detection and intervention and justify a follow up protocol for life in susceptible patients if additional handicaps are to be prevented.23 Surprisingly, in 18–54% of TCS patients the conus medullaris is at the normal level.24–27 The diagnosis of TCS can be difficult in patients with a fatty filum terminale and conus at Author's personal copy Tethered cord syndrome: A study of 35 patients 27 The possibility of re-tethering after the initial operation has generated much attention. Various suggestions and techniques for minimizing the incidence of re-tethering have been proposed, but none has proved to be completely effective or superior.15 Certain high-risk patients should be evaluated prospectively for TCS. Nogueira et al.29 recommended that all patients with VACTERL syndrome (Vertebral abnormality, Anal imperforation, Cardiac malformation, TracheoEsophageal fistula, Renal abnormalities, Limb deformities, OMIM No. 192350) should be evaluated prospectively for TCS. Mitsuka et al.18 recommended that if a twin or sibling of an affected person has appropriate symptoms with stigmata of spinal dysraphism, he or she should undergo investigations early. Conclusion Figure 3: Sagittal MRI scan T2-weighted image showing a tethered cord secondary to thick filum terminale. a normal level, especially in the absence of the typical clinical features of the syndrome. Therefore, a patient who has the signs and symptoms of tethered cord in the presence of normal radiology should be referred to a specialized center to confirm or exclude the diagnosis. Despite its frequent asymptomatic course, the diagnosis of a congenital lumbosacral lipoma, and more general of a closed spinal dysraphism, implies a periodic, multidisciplinary follow-up for life.28 Yamada and Lonser14 listed magnetic resonance imaging clues to aid the diagnosing TCS: (1) thick filum terminale (>2 mm in diameter) or the presence of structures that suggest the lack of viscoelasticity (e.g. a fibroadipose filum terminale, obliteration of the subarachnoid space suggesting adhesion around the caudal spinal cord or nerve roots, a dermoid or epidermoid mass, myelomeningocele, or lipomeningomyelocele); (2) an elongated spinal cord; (3) posterior displacement of the conus medullaris with the filum pressing against the thecal lining at or near the L5 lamina seen on sagittal and axial sections, which is a constant finding. A capacious sacral subarachnoid space is not uncommon. In patients who were asymptomatic during childhood, but developed symptoms of TCS after adolescence, the only imaging finding may be a posteriorly displaced conus medullaris and filum terminale.14 A patient’s lower urinary tract should also be evaluated. Urodynamic studies are sensitive indicators of lower tract compromise when interpreted properly. When available, this would be the preferred examination. Follow-up urodynamic studies are often the first indicator of retethering effects, perhaps before the patient is aware of any changes in function and certainly before any changes can be found in the neurological system.15 This study of the natural history of TCS showed that 68.4% of patients over 2 years of age developed progressive neurological deficits. Hence, TCS patients must be referred and treated by the age of 2 years, or soon after the diagnosis in late presenters. 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