ORIGINAL PAPER. Mehmet Selçuki & Ahmet Şükrü Umur & Yusuf Kurtulus Duransoy & Seymen Ozdemir & Deniz Selcuki

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1 DOI /s ORIGINAL PAPER Inappropriate surgical interventions for midline fusion defects cause secondary tethered cord symptoms: implications for natural history report of four cases Mehmet Selçuki & Ahmet Şükrü Umur & Yusuf Kurtulus Duransoy & Seymen Ozdemir & Deniz Selcuki Received: 12 January 2012 / Accepted: 28 January 2012 # Springer-Verlag 2012 Abstract Introduction The causes of tethered spinal cord are various. In order to release the tethering effect of these malformations, the surgical interventions must include removal of all tethering components, reconstruction of the neural tube and sectioning of tight filum terminale as well. Cases The cases reported in this paper have had an operation many years before for various developmental defects. After a certain period of time (5 10 years) of the first operation, the patients reapplied to the hospital with various symptoms of spinal cord tethering, either vertical or horizontal. Discussion At surgical intervention, it was noted that inappropriate surgical procedures caused retethering of the spinal cord in all patients. Postoperative period of all patients were uneventful. All patients declared relief in their symptoms. We would like to draw attention that untreated (or inappropriately treated) midline developmental defects will invariably cause syndrome of tethered cord. Consequently, prophylactic surgical untethering must be applied to all patients with developmental midline defects as soon as possible. Conclusion It looks that tethered cord symptoms invariably appear as enough negative influence accumulates as the time passes. Elapsed time may vary but unpleasant end result invariably arrives. While these cases with tethered spinal cord develop progressive neurological symptoms, prophylactic and M. Selçuki (*) : A. Ş. Umur : Y. K. Duransoy : S. Ozdemir Neurosurgery Department, Celal Bayar University, Medical School, 1403 sk 5/8 Alsancak, Izmir, Turkey mselcuki@yahoo.com D. Selcuki Neurology Department, Celal Bayar University, Medical School, Manisa, Turkey appropriate surgical intervention should be considered as early as possible. There is no acceptable rationale to wait for the appearance of tethered cord syndrome symptoms to perform surgical untethering of the spinal cord because of the probability of irreversibility of the symptoms (incontinence of urine in particular) of tethered spinal cord syndrome. Keywords Split cord. Tethered spinal cord. Scoliosis. Midline fusion defects Introduction During neurulation (either primary or secondary), the length of neural tissue and surrounding mesodermal tissues are equal to each other. However, at approximately 55 days of development, mesodermal tissues covering the neural tissue begin to grow faster than neural tissue and consequently neural tissue, spinal cord in particular, becomes shorter than surrounding tissues, i.e., spinal column. Should a developmental defect take place before this uneven growth begins, neural tissue sticks to the surrounding tissues and tethering of the spinal cord occurs as the neural tissue cannot ascend to the higher levels. Not only vertical tethering causes tethered cord syndrome but also lateral or posterior tethering of the spinal cord may also cause tethered cord syndrome symptoms. The main aim of the surgical procedures for developmental defects is to release tethering forces that have effect on spinal cord. However, this was not the case in the patients that we present here. In case 1, inappropriate resection of the cervical sac and a surgical intervention without having reconstruction of the neural placode done was performed, consequently resulted with adhesion of neural tissue to surrounding tissues. In case 2, lumbar myelomeningocele

2 (mmc), it is noted that the neural placode was adhered to the surface layer with its entire surface, which is considered as neural placode was not reconstructed and massive adhesion has occurred instead of linear cling. In case 3, split cord malformation type I, it is determined that only bony spur was removed and dural sheath, dorsal medial roots, and thick filum terminale were left untouched, which does not contribute relieving tethering effect of split cord malformation. In the last case, case 4, L4 mmc had the same reason that the spinal cord should be tethered as in case 2. Unfortunately, although there is not enough data about the previous operations of the cases because of the reasons listed above in a case orderly base, all of the surgical interventions that applied to the cases were considered as inappropriate as far as the inadequate attempts of untethering of the spinal cord concerned. If these maneuvers have not been done appropriately during the first operation, the tethering of spinal cord either continues or newly formed tethering starts effect on spinal cord as if it has not been released previously and symptoms of tethered cord syndrome appear. Thus, we considered such patients as untreated spinal cord tethering patients and thought that they may contribute to natural history of tethered spinal cord. In this paper, four patients are presented with different midline developmental defects (Table 1). Cases Cases are presented as listed in Table 1 Case 1 This 28-year-old male patient applied to our neurology department with the chief complaint of weakness in both arms and legs. He described a clinical table of quadriparesis and urinary incontinence. Incontinence began 2 years before as urgency leak but progressed to complete incontinence. In the history, he had a neck operation when he was 2 year old. He did not have a discharge report so we could not determine the surgical intervention that he had previously. As he is noted, postoperative period was uneventful until he was 26 years old. During the last 2 years, he experienced progressive weakness in both arms first and legs and urine incontinence was added to this table as the time passes. Although he was fine at the beginning of the symptoms and was able to play soccer with his friends, at the time of hospital application, he was already bedridden and could hardly achieve standup position with considerable external support provided by his parents. His magnetic resonance (MR) images revealed that the previous surgical intervention was done for cervical mmc (Fig. 1a). However, inappropriate surgical intervention caused postero-lateral adhesion and tethering of the spinal cord itself. Urodynamic study revealed neurogenic hipocompliant bladder with hyperreflexive contractions during Table 1 Summary of four patients is shown in the table Gender MRI Developmental defect New symptoms Duration of symptoms Post-op result of 2nd op Post-op result 1st op Patient Age Age at first op 1 HU 28 2 Uneventful Quadriparesis 18 Months Good Cervical mmc M Posterior tethering of spinal cord at the site of previous operation Fair Lumbar mmc M Vertical tethering of the spinal cord. Neural placode got stuck at the site of mmc and epidermoid mass at a lower level. 2 MCE 5 10/365 Uneventful Incontinence 18 Months, incontinence began after toilet training at 3.5 years of age F Dural sheath of bony spur and two halves of spinal cord in different dural sheaths 6 Months Good L2 3 split cord malformation type 1 3 HA 11 1 Uneventful Scoliosis, developed in three months and progressed 15 degrees in 45 days Fair L4 mmc F Neural placode got stuck at the site of previous operation, with all of its surface 4 ND 8 15/365 Uneventful Incontinence 18 Months, incontinence began after establishment of toilet training at age four The interesting point is that the symptoms regarding the cord tethering appeared long after the previous surgical intervention. Elapsed time may vary but unpleasant end result invariably arrives

support and was discharged to physical rehabilitation center with clean intermittent catheterization for his urinary incontinence. He declared better sensation from his legs and arms.

3 support and was discharged to physical rehabilitation center with clean intermittent catheterization for his urinary incontinence. He declared better sensation from his legs and arms. Case 2 This 5-year-old male patient was born with lumbar mmc. He had mmc repair operation soon after birth. As his parents noted, postoperative period was uneventful. He did not need a cerebrospinal fluid shunting procedure. He gained toilet training when he was 3.5 years old. He could hardly walk with parents' support. Five years after the previous operation, he began to walk distorted and began not to hold his urine and this problem progressed to be a full urinary incontinence in 18 months. He was unable to walk, even with considerable support, at the time he applied to hospital. His MR images revealed that neural placode was adhered to the previous site of surgical intervention, most probably due to not reconstructed neural placode, which was adhered to the operation site with its entire surface (Fig. 2a, arrow) and an epidermoid mass (Fig. 2b, arrows)distaltothe previous operation site. SSEP revealed total conduction block at lumbar and thoracic levels. Urodynamic studies showed neurogenic bladder with decreased capacity and hyperreflexive contractions during filling phase. During reoperation, the unreconstructed neural placode was noticed and repaired, adhesions to surrounding tissues dissected and releasing of the spinal cord was accomplished. During early postoperative period, total urinary incontinence turned to be an urgency leak. He declared relaxation of her legs muscles just before she was discharged. Fig. 1 a Posteriorly tethered spinal cord after previous inappropriate surgical intervention 26 years ago. b After untethering process, released spinal cord can be noticed filling phase. Spinal somatosensorial-evoked potential (SSEP) study showed total blockade of conduction at cervical level. At reoperation, adhesions of tethered spinal cord to dorsal layers were dissected and after reconstruction of the neural placode, the dura mater was closed (Fig. 1b). At postoperative tenth day, he was able to stand up with minor Case 3 This 11-year-old female patient applied with the chief complaint of bending of her spine. She had an operation because of split cord malformation type I when she was 1 year old. Postoperative period was uneventful. Six months before the admission, she was 10.5 years old, her mother noted bending of her spine while she was taking bath. As the angle of bending increased, she applied to our neurosurgery clinic. At that time, the neurological examination was normal and the Cobb angle was 35 with a bending to spinal column to left. As she was operated on because of split cord malformation type I, 10 years ago, we decided to follow-up the angle of scoliosis at certain intervals. However she reapplied 2 months later because of the increase of bending in her spine. This time, the angle of scoliosis was measured as 45. Her MR images revealed split cord malformation type I at L2 level. Although there was no visible bony spur in between, remained dural sheath of bony spur and thick filum terminale were noted, which means spinal cord is still under the effect of tethering (Fig. 3, arrow). During reoperation, the sheath of bony spur was removed, dorsal midline roots were sectioned, and thick filum

While the degree of scoliosis got worse very rapidly during the preoperative period, steady state of the angle after the operation let us hope that the angle of scoliosis may at least be stable.

4 a b Childs Nerv Syst terminale was sectioned. Early postoperative course was uneventful. At follow-up examination, 1 month after the operation, we did not note improvement of the angle of scoliosis, but the angle was same with preoperative degree. While the degree of scoliosis got worse very rapidly during the preoperative period, steady state of the angle after the operation let us hope that the angle of scoliosis may at least be stable. Case 4 This 8-year-old female patient admitted to the hospital with the chief complaint of difficulty in walking and incontinence. She had a lumbar mmc operation soon after her birth. Postoperative period of first operation was uneventful. She has gained toilet training when she was 3.5 years old. However, her walking difficulty began about 18 month ago and she began to experience incontinence as well. Her neurological examination was almost normal, except mild weakness of her both legs. Her MR images revealed an adhered neural placode to L3 level with its entire surface to dorsal border of operative field (Fig. 4). During the second operation, the neural placode was separated from the tissues that it adhered, reconstruction of placode was done, and thick filum terminale was sectioned. Early postoperative period was uneventful. At the time of discharge, at the tenth postoperative day, she began to partially control her bladder and declared that she could control her legs better than preoperative period. Discussion Fig. 2 a Inappropriately managed mmc. Neural placode has adhesion to surrounding tissue with its entire surface (arrow). b Inappropriate surgical intervention caused epidermoid mass as well (arrow) Fig. 3 After having bony spur removed 26 years ago, thick filum terminale, and dural sheath of bony spur (arrow) kept tethering effect of the maldevelopment alive While the faster growth of spinal column as compared to the spinal cord begins at about the 55th gestational day, incomplete either primary or secondary neurulation causes adhesion of neural tissue to the surrounding tissues. In a study that investigated the level conus medullaris in first week of birth in either mature or premature babies, the level of conus medullaris in 98% was found to be at L2 level, which is very close to the level with adults. The remainder 2% were reportedly sick babies with Down's syndrome. In that paper, the authors concluded that while the ascent of conus medullaris has already been almost completed by the time of birth, then it means that if there is spinal cord tethering due to any kind of midline developmental defect, the adverse effects of cord tethering is present at time of birth [1]. Yamada et al. reported in their 1981 paper that tethering causes relative ischemia in the part of tethered spinal cord and this relative ischemia causes cumulative negative effect in mitochondrial energy production. The clinical symptoms related to the tethered cord syndrome appear as the enough amount of negative influence accumulates, which is indisputably a matter of time [2]. There are sporadic reports of natural

5 history of untreated midline developmental defects [3, 4]. Although there are no real natural historical reports of all kind of midline developmental defects, in a study that investigated the natural outcome of occult spina bifida, the authors concluded that the surgical intervention for either untethering or repair of the maldevelopment should be achieved as soon as possible [4]. In another study that tried to investigate the natural history of the babies with myelomeningocele, the authors reported that the early surgical intervention is much more helpful for bladder functions as compared to the delayed repair [5]. Difficulty in gathering untreated midline developmental defect cases makes it hard to draw a concrete conclusion about the natural history of the disease. Sporadic but important as well, the papers about the natural history suggested the early surgical untethering of the spinal cord. In this context, not only untreated cases of midline developmental defects are noteworthy but also the inappropriately operated cases constitute a considerable amount of cases in whom the natural history of the disease can be analyzed. In this paper, we presented four cases of inappropriately operated for various kinds of midline developmental defects. In fact, although the patients were operated on for their malformations, adequate untethering could be achieved in none of them. While untethering could not be achieved, in other words, it means that tethering of the cord continued as it originally was, and kept its own natural way through its own history. One of our patients is improperly operated on split cord malformation, one of them did not have untethered thick filum terminale, one of them is a myeleomeningocele with a wide neural placode surface and did not have repair and reconstruction, and finally last but not least, is a cervical myelomeningocele whose sac was resected without reconstructing the neural placode and the adhesions to the surrounding tissue were cleared. The untethered fila may retether and symptoms of tethered cord may appear. Yong et al. reported that 8.6% of the untethered fila patients develop symptomatic retethering after sometime [6]. We did not encounter retethering of filum terminale in the so-called primary tethered fila (filum terminale with a normal appearance) patients. Retethering is higher, expectedly, in sectioned fatty fila terminalia as reported by Ogiwara et al. [7]. However, our cases, although a small series, did not develop retethering, instead they have not untethered at all. This is a major point why these cases were selected to study natural history of the tethered cord syndrome. This series of patients can be considered as not treated tethered cord patients because of the inappropriate surgical interventions and can be a good example for natural history of the spinal cord tethering. All patients did well for a period of time. Cervical myelomeningocele patient did well for as long as 26 years, and at the end, he was bedridden at the age of 28. Untethered or not properly untethered spinal cords behave in the same manner and although such patients may keep going asymptomatic on their own way, the elapsed time may vary but unpleasant outcome invariably arrives. From a different point of view, after these four cases, we thought that inadequate neurosurgical training may be a reason for these inappropriate surgical interventions. Adequate training either during neurosurgical residency or during internship of the medical students is of prime importance to avoid redundant delays and wrong operative procedures in repair of such developmental malformations. Conclusion Fig. 4 Although skin lesion has been removed soon after birth, untethering procedure has not been completed (arrow), which, in turn, ends up with incontinence and walking disturbances 1. It looks that tethered cord symptoms invariably appear as enough negative influence accumulates as the time passes. Elapsed time may vary but unpleasant end result invariably arrives. 2. While these cases with tethered spinal cord develop progressive neurological symptoms, prophylactic and appropriate surgical intervention should be considered as early as possible. 3. There is no acceptable rationale to wait for the appearance of tethered cord syndrome symptoms to perform surgical untethering of the spinal cord because of the probability of irreversibility of the

6 symptoms (incontinence of urine in particular) of tethered spinal cord syndrome. References 1. Şahin F, Selçuki M, Zenciroğlu A, Ünlü A, Yılmaz F, Maviş N, Sarıbaş S (1997) Level of conus medullaris in term and preterm neonates. Fetal Neonatal 77(1): Yamada S, Zinke DE, Sanders D (1981) Pathophysiology of tethered cord syndrome. J Neurosurg 54: Koyanagi I, Iwasaki Y, Hida K, Abe H, Isu T, Akino M (1997) Surgical treatment supposed natural history of the tethered cord with occult spinal dysraphism. Child's Nerv Syst 13: Phuong LK, Schoeberl KA, Raffel C (2002) Natural history of tethered cord in patients with meningomyelocele. Neurosurgery 50 (5): Tarcan T, Onol FF, Ilker Y, Alpay H, Simşek F, Ozek M (2006) The timing of primary neurosurgical repair significantly affects neurogenic bladder prognosis in children with myelomeningocele. J Urol 176(3): Yong RL, Bach-Habrock T, Vaughan M, Kestle JR, Steinbok P (2011) Symptomatic retethering of the spinal cord after section of a filum terminale. Neurosurgery 68(6): Ogiwara H, Lyszczarz A, Alden TD, Bowman RM, McLOne DG, Tomita T (2011) Retethering of transected fatty filum terminales. J Neurosurg Pediatr 7(1):42 46

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