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A split cord malformation with paresis of the unilateral lower limb: case report
A Split Cord Malformation with Paresis of the Unilateral Lower Limb: Case Report Kenichi Sato, M.D., Yasuko Yoshida, M.D., Reizo Shirane, M.D., and Takashi Yoshimoto, M.D. Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendei, Japan
Sato K, Yoshida Y, Shirane R, Yoshimoto T. A split cord malformation with paresis of the unilateral lower limb: case report. Surg Neurol 2002;58:406 –9. BACKGROUND
We report a rare case of split cord malformation. CASE DESCRIPTION
A female neonate presented with split cord malformation (SCM) manifesting as right lower limb paresis. Myelomeningocele and meningocele were found in the lumbosacral region at birth. Magnetic resonance imaging (MRI) demonstrated division of the spinal cord into two hemicords below the T5 level. The right hemicord formed a hemimyelomeningocele and the left hemicord terminated in the low-lying conus. Three-dimensional computed tomography (3D CT) showed extensive vertebral body abnormalities. The hemimyelomeningocele was repaired 1 day after birth, and septectomy and the repair of the meningocele were performed when the patient was 1 year old. The patient has been followed up as an outpatient, and has residual right lower limb paresis. CONCLUSION
SCM can be associated with multiple spinal abnormalities. MRI and 3D-CT are useful for identifying such abnormalities and planning the surgical treatment. © 2002 by Elsevier Science Inc. KEY WORDS
Magnetic resonance imaging, split cord malformation, threedimensional computed tomography.
plit cord malformation (SCM) is the general term for malformations involving two spinal cords, including diplomyelia and diastematomyelia. Pang in 1992 [9,10] classified SCM into two broad groups: Type I, which consists of two hemicords, each contained within its own dural tube and separated by a rigid osseocartilagenous median septum, and Type II, which consists of two hemicords
S
Address reprint requests to: Kenichi Sato, Department of Neurosurgery, Tohoku University Graduate School of Medicine, Seiryo-Machi, Aoba-Ku, Sendei, Japan. Received August 30, 2001; accepted July 19, 2002. 0090-3019/02/$–see front matter PII S0090-3019(02)00897-2
housed in a single dural tube separated by a nonrigid fibrous median septum. Here, we report a case of SCM associated with multiple spinal anomalies, including low-lying conus, meningocele, hemimyelomeningocele, and syrinx, which manifested as right lower limb paresis at birth.
Case Report A female neonate was delivered spontaneously at full term. Two separate mass lesions and abnormal hypertrichosis were found in the lumbosacral region. The rostrally sited mass located at the L3 level was 2 cm in diameter and was covered by skin. The caudally sited mass located at the S1 level was 4 cm in diameter and covered by a thin translucent membrane, and had cerebrospinal fluid leaking from it. She had clubfoot and decreased response to painful stimuli below the L1 level on the right, and suffered from bladder dysfunction (Figure 1). There were no morphologic or neurologic abnormalities in the left lower limb. Coronal magnetic resonance imaging (MRI) revealed that the spinal cord had divided into two hemicords below the T5 level (Figure 2a). The right hemicord terminated in a hemimyelomeningocele at the S1 level, and the left hemicord became the low-lying conus. The spinal cord above the split portion was swollen with syrinx. Axial MRI showed two hemicords, each containing a syrinx, in one dural tube (Figure 2b). Sagittal MRI revealed that the inner part of the rostrally sited mass lesion presented isointense to the CSF and did not contain any of the spinal cord, so the rostral lesion was thought to be a meningocele (Figure 2c, also see Figure 2b-2). Three-dimensional computed tomography (3D CT) showed scoliosis, extensive incomplete neural arches, vertebral body abnormalities © 2002 by Elsevier Science Inc. 360 Park Avenue South, New York, NY 10010 –1710
Split Cord Malformation
Photograph showing two masses in the median thoracolumbar region. The rostrally sited mass is covered by skin, and the caudally sited mass is covered by a thin translucent membrane, and has cerebrospinal fluid leaking from it. Abnormal hypertrichosis between the two masses is recognized. There is clubfoot on the right.
1
involving the upper thoracic to the sacral level, and abnormal hypertrophic laminae at the thoracic level (Figure 3). The hemimyelomengocele was repaired 1 day after birth because of the risk of ulceration and infec-
Surg Neurol 407 2002;58:406 –9
tion. Incision of the dural tube exposed the right hemicord, composed of neural placode (Figure 4a), and the left hemicord (Figure 4b). The conus end of the left hemicord could not be seen in the surgical field. The hemimyelomeningocele was repaired. Removal of the septum and repair of the meningocele were performed prophylactically 1 year later when the patient was able to withstand the invasive procedure. Laminectomy was performed from T3 to T8. Abnormal hypertrophic laminae were removed and two hemicords and a fibrous median septum were seen at the thoracic level. This fibrous septum was removed (Figure 4c). Intraoperatively a hole that opened into the dural tube appeared, but a fibrous band and herniated nerve roots, which might tether the spinal cord, were not found in the meningocele. The meningocele was repaired. The postoperative course was uneventful with no further neurologic deficits. At the follow-up the patient continues to do well, with residual lower limb weakness and bladder dysfunction.
Discussion There is a general consensus that all SCMs originate from one basic ontogenetic error occurring around
(a) Coronal T1-weighted MR image showing total division of the spinal cord below the T5 level with hemimyelomeningocele in the right hemicord. (b) Axial T1-weighted MR image. Two hemicords are housed in one dural tube and each hemicord has a syrinx (b-1). The rostrally sited mass does not seem to contain any of the spinal cord (b-2). (c) Sagittal MR image. The rostrally sited mass connects with the dural tube and its inner part is isointense to CSF.
2
408 Surg Neurol 2002;58:406 –9
Three-dimensional CT scan showing scoliosis, extensive incomplete neural arches, vertebral body abnormalities involving the upper thoracic to the sacral levels, and abnormal hypertrophic laminae at the thoracic level.
3
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Sato et al
the time when the primitive neuroenteric canal closes [3,5,8,10,12]. This basic error is the formation of an accessory neuroenteric canal through the midline embryonic disc that maintains communication between the yolk sac and amnion, and enables continued contact between the ectoderm and endoderm within the canal. In this case, the left hemicord terminates with hemimyelomeningocele and the right low-lying conus. It is possible that hemicords undergo primary neurulation after the formation of the hemi-neural plates. And the neurulation process in each hemicord, normal or abnormal, may be independent of its counterpart and be subject to the same teratogenic error as in the common variety of open myelomeningocele and low-lying conus. The most common neurologic symptoms are delayed tethered cord syndrome, found in about 85% of cases of SCM [5]. Asymmetric symptoms in the lower limbs caused by asymmetric hemicords, associated hemimyelomeningocele, are important for differentiation from other diseases causing tethered cord syndrome [5,8]. Because most cases of SCM are associated with extensive vertebral body abnormalities, SCM should be suspected in patients with extensive vertebral abnormalities, and incompatibility between the vertebral body abnormality and the vertebral levels of the neurologic symptoms [2,4,9,12]. SCM without other malformations is rare, so investigation of the whole central nervous system is recommended [7,11]. In this case, MRI was useful for demonstrating the associated nervous system anomalies as well as for
Intraoperative photographs showing (a) placode of the right hemicord (arrowhead), (b) the left hemicord (arrow), and (c) hemicords after the removal of the fibrous septum.
Split Cord Malformation
identifying SCM. 3D CT was superior for investigating the structure of the abnormal hypertrophic laminae and vertebral body abnormalities, and provided useful information for the laminotomy. Previous investigators have shown the usefulness of CT myelography for detecting SCM [4,6,9], but we did not use that in the present case, because myelography is invasive and carries a risk of spinal cord damage by needle puncture or possible bleeding from abnormal vessels associated with the suspected spinal cord abnormality [10]. Therefore, we assumed that the combination of MRI and 3D CT could provide sufficient information for surgical planning. Tethered cord syndrome associated with SCM is usually caused by the septum, so should be treated by septectomy; and this procedure results in resolution or improvement of the neurologic symptoms caused by the tethered cord [1,2,4 –9,11,12]. Patients with asymptomatic SCM may have neurologic symptoms triggered by trauma or overextension of the spine, so prophylactic septectomy is recommended [9,11]. The timing of the operation should be considered carefully, since almost all patients are neonates or infants. Recent reports have concluded that surgery for SCM seems to be effective, particularly for preventing neurologic deterioration, but is not effective in treating neuroorthopedic deterioration [8]. Our patient presented with right lower limb paresis at birth, which could be classified as a neuro-orthopedic syndrome. Septectomy for such cases is not so urgent, contrary to previous indications [4,9], and is not the first priority of treatment, especially in neonates because of the extensive lesions associated with other pathologies and the difficulty of obtaining preoperative information. In conclusion, we report a case of split cord malformation associated with multiple spinal anomalies. The combination of MRI and 3D CT is useful for identifying spinal anomalies and planning the surgical treatment. REFERENCES 1. Ander UB, Harkness WFJ, Hayward RD. Split cord malformations of the lumber region. Pediatr Neurosurg 1997;26:17–24. 2. Anzai T, Kato I, Shirane R, Ogawa A, Yoshimoto T. [A case of diastematomyelia with meningomyelocele.] No Shinkei Geka 1992;20:261–5 (Jpn). 3. Emura T, Asashima M, Hasgizume K. An experimental animal model of split cord malformation. Pediatr Neurosurg 2000;33:283–92. 4. Ersahin Y, Demitras E, Mutluer S, Tosun AR, Saydam S. Split cord malformations: report of three unusual cases. Pediatr Neurosurg 1996;24:155–9.
Surg Neurol 409 2002;58:406 –9
5. Ersahin Y, Mutlur S, Kokaman S, Demitras E. Split cord malformation in children. J Neurosurg 1998;88:57– 65. 6. Katoh M, Hida K, Iwasaki Y, Koyanagi I, Abe H. A split cord malformation. Childs Nerv Syst 1998;14:398 – 400. 7. Koyama S, Sekido K, Yamaguchi K. [Two cases of diastematomyelia: its evaluation with MR imaging.] No Shinkei Geka 1989;17:393– 8 (Jpn). 8. Kumar R, Bansal KK, Chhabra DK. Split cord malformation (SCM) in paediatric patients. Neurol India 2001;49:128 –33. 9. Pang D. Split cord malformation: Part II: Clinical syndrome. Neurosurgery 1992;31:481–500. 10. Pang D, Dias MS, Ahab-Barmada M. Split cord malformation: Part I: a unified theory of embryogenesis for double spinal cord malformation. Neurosurgery 1992; 31:451– 80. 11. Prasad VS, Senger RL, Sahu BP, Immaneni D. Diastematomyelia in adults. Modern imaging and operative treatment. Clin Imaging 1995;19:270 – 4. 12. Totori-Donati P, Rossi A, Cama A. Spinal dysraphism: a review of neurological features with embryological correlations and proposal for a new classification. Neuroradiology 2000;42:471–91. COMMENTARY
Sato et al report an uncommon case of split cord malformation. The patient was a newborn who was born with a multiple myelomeningocele sacs, at L2 and S1, with unilateral lower limb weakness (asymmetric motor involvement). MRI showed two hemicords below the level of T5, which share the same meninges. Three-dimensional CT showed extensive vertebral anomalies as well. The myelomeningocele was repaired the next day. The authors found that MRI and 3D CT provided useful information for surgical planning. The MRI provided a good-quality view of the deranged anatomy of the hemicords, hydromyelia, and Type II split cord malformation. Three-dimensional CT added information about the bony anomalies. it has been a valuable addition to our practice as well. As the authors point out, a low-lying spinal cord is not necessarily the same as a tethered cord, although these terms have been used interchangeably. Resection of the septum is not always the first-line treatment, as least in newborns. The authors state that the rostral sac was a meningocele. In my experience, what may appear to be a meningocele on MRI always retains some neural elements or fibers—a pure meningocele is extremely rare. I congratulate the authors on their excellent surgical planning and good results. Yoon S. Hahn, M.D. Department of Neurosurgery University of Illinois at Chicago Chicago, Illinois
Sato K, Yoshida Y, Shirane R, Yoshimoto T. A split cord malformation with paresis of the unilateral lower limb: case report. Surg Neurol 2002;58:406 –9. BACKGROUND
We report a rare case of split cord malformation. CASE DESCRIPTION
A female neonate presented with split cord malformation (SCM) manifesting as right lower limb paresis. Myelomeningocele and meningocele were found in the lumbosacral region at birth. Magnetic resonance imaging (MRI) demonstrated division of the spinal cord into two hemicords below the T5 level. The right hemicord formed a hemimyelomeningocele and the left hemicord terminated in the low-lying conus. Three-dimensional computed tomography (3D CT) showed extensive vertebral body abnormalities. The hemimyelomeningocele was repaired 1 day after birth, and septectomy and the repair of the meningocele were performed when the patient was 1 year old. The patient has been followed up as an outpatient, and has residual right lower limb paresis. CONCLUSION
SCM can be associated with multiple spinal abnormalities. MRI and 3D-CT are useful for identifying such abnormalities and planning the surgical treatment. © 2002 by Elsevier Science Inc. KEY WORDS
Magnetic resonance imaging, split cord malformation, threedimensional computed tomography.
plit cord malformation (SCM) is the general term for malformations involving two spinal cords, including diplomyelia and diastematomyelia. Pang in 1992 [9,10] classified SCM into two broad groups: Type I, which consists of two hemicords, each contained within its own dural tube and separated by a rigid osseocartilagenous median septum, and Type II, which consists of two hemicords
S
Address reprint requests to: Kenichi Sato, Department of Neurosurgery, Tohoku University Graduate School of Medicine, Seiryo-Machi, Aoba-Ku, Sendei, Japan. Received August 30, 2001; accepted July 19, 2002. 0090-3019/02/$–see front matter PII S0090-3019(02)00897-2
housed in a single dural tube separated by a nonrigid fibrous median septum. Here, we report a case of SCM associated with multiple spinal anomalies, including low-lying conus, meningocele, hemimyelomeningocele, and syrinx, which manifested as right lower limb paresis at birth.
Case Report A female neonate was delivered spontaneously at full term. Two separate mass lesions and abnormal hypertrichosis were found in the lumbosacral region. The rostrally sited mass located at the L3 level was 2 cm in diameter and was covered by skin. The caudally sited mass located at the S1 level was 4 cm in diameter and covered by a thin translucent membrane, and had cerebrospinal fluid leaking from it. She had clubfoot and decreased response to painful stimuli below the L1 level on the right, and suffered from bladder dysfunction (Figure 1). There were no morphologic or neurologic abnormalities in the left lower limb. Coronal magnetic resonance imaging (MRI) revealed that the spinal cord had divided into two hemicords below the T5 level (Figure 2a). The right hemicord terminated in a hemimyelomeningocele at the S1 level, and the left hemicord became the low-lying conus. The spinal cord above the split portion was swollen with syrinx. Axial MRI showed two hemicords, each containing a syrinx, in one dural tube (Figure 2b). Sagittal MRI revealed that the inner part of the rostrally sited mass lesion presented isointense to the CSF and did not contain any of the spinal cord, so the rostral lesion was thought to be a meningocele (Figure 2c, also see Figure 2b-2). Three-dimensional computed tomography (3D CT) showed scoliosis, extensive incomplete neural arches, vertebral body abnormalities © 2002 by Elsevier Science Inc. 360 Park Avenue South, New York, NY 10010 –1710
Split Cord Malformation
Photograph showing two masses in the median thoracolumbar region. The rostrally sited mass is covered by skin, and the caudally sited mass is covered by a thin translucent membrane, and has cerebrospinal fluid leaking from it. Abnormal hypertrichosis between the two masses is recognized. There is clubfoot on the right.
1
involving the upper thoracic to the sacral level, and abnormal hypertrophic laminae at the thoracic level (Figure 3). The hemimyelomengocele was repaired 1 day after birth because of the risk of ulceration and infec-
Surg Neurol 407 2002;58:406 –9
tion. Incision of the dural tube exposed the right hemicord, composed of neural placode (Figure 4a), and the left hemicord (Figure 4b). The conus end of the left hemicord could not be seen in the surgical field. The hemimyelomeningocele was repaired. Removal of the septum and repair of the meningocele were performed prophylactically 1 year later when the patient was able to withstand the invasive procedure. Laminectomy was performed from T3 to T8. Abnormal hypertrophic laminae were removed and two hemicords and a fibrous median septum were seen at the thoracic level. This fibrous septum was removed (Figure 4c). Intraoperatively a hole that opened into the dural tube appeared, but a fibrous band and herniated nerve roots, which might tether the spinal cord, were not found in the meningocele. The meningocele was repaired. The postoperative course was uneventful with no further neurologic deficits. At the follow-up the patient continues to do well, with residual lower limb weakness and bladder dysfunction.
Discussion There is a general consensus that all SCMs originate from one basic ontogenetic error occurring around
(a) Coronal T1-weighted MR image showing total division of the spinal cord below the T5 level with hemimyelomeningocele in the right hemicord. (b) Axial T1-weighted MR image. Two hemicords are housed in one dural tube and each hemicord has a syrinx (b-1). The rostrally sited mass does not seem to contain any of the spinal cord (b-2). (c) Sagittal MR image. The rostrally sited mass connects with the dural tube and its inner part is isointense to CSF.
2
408 Surg Neurol 2002;58:406 –9
Three-dimensional CT scan showing scoliosis, extensive incomplete neural arches, vertebral body abnormalities involving the upper thoracic to the sacral levels, and abnormal hypertrophic laminae at the thoracic level.
3
4
Sato et al
the time when the primitive neuroenteric canal closes [3,5,8,10,12]. This basic error is the formation of an accessory neuroenteric canal through the midline embryonic disc that maintains communication between the yolk sac and amnion, and enables continued contact between the ectoderm and endoderm within the canal. In this case, the left hemicord terminates with hemimyelomeningocele and the right low-lying conus. It is possible that hemicords undergo primary neurulation after the formation of the hemi-neural plates. And the neurulation process in each hemicord, normal or abnormal, may be independent of its counterpart and be subject to the same teratogenic error as in the common variety of open myelomeningocele and low-lying conus. The most common neurologic symptoms are delayed tethered cord syndrome, found in about 85% of cases of SCM [5]. Asymmetric symptoms in the lower limbs caused by asymmetric hemicords, associated hemimyelomeningocele, are important for differentiation from other diseases causing tethered cord syndrome [5,8]. Because most cases of SCM are associated with extensive vertebral body abnormalities, SCM should be suspected in patients with extensive vertebral abnormalities, and incompatibility between the vertebral body abnormality and the vertebral levels of the neurologic symptoms [2,4,9,12]. SCM without other malformations is rare, so investigation of the whole central nervous system is recommended [7,11]. In this case, MRI was useful for demonstrating the associated nervous system anomalies as well as for
Intraoperative photographs showing (a) placode of the right hemicord (arrowhead), (b) the left hemicord (arrow), and (c) hemicords after the removal of the fibrous septum.
Split Cord Malformation
identifying SCM. 3D CT was superior for investigating the structure of the abnormal hypertrophic laminae and vertebral body abnormalities, and provided useful information for the laminotomy. Previous investigators have shown the usefulness of CT myelography for detecting SCM [4,6,9], but we did not use that in the present case, because myelography is invasive and carries a risk of spinal cord damage by needle puncture or possible bleeding from abnormal vessels associated with the suspected spinal cord abnormality [10]. Therefore, we assumed that the combination of MRI and 3D CT could provide sufficient information for surgical planning. Tethered cord syndrome associated with SCM is usually caused by the septum, so should be treated by septectomy; and this procedure results in resolution or improvement of the neurologic symptoms caused by the tethered cord [1,2,4 –9,11,12]. Patients with asymptomatic SCM may have neurologic symptoms triggered by trauma or overextension of the spine, so prophylactic septectomy is recommended [9,11]. The timing of the operation should be considered carefully, since almost all patients are neonates or infants. Recent reports have concluded that surgery for SCM seems to be effective, particularly for preventing neurologic deterioration, but is not effective in treating neuroorthopedic deterioration [8]. Our patient presented with right lower limb paresis at birth, which could be classified as a neuro-orthopedic syndrome. Septectomy for such cases is not so urgent, contrary to previous indications [4,9], and is not the first priority of treatment, especially in neonates because of the extensive lesions associated with other pathologies and the difficulty of obtaining preoperative information. In conclusion, we report a case of split cord malformation associated with multiple spinal anomalies. The combination of MRI and 3D CT is useful for identifying spinal anomalies and planning the surgical treatment. REFERENCES 1. Ander UB, Harkness WFJ, Hayward RD. Split cord malformations of the lumber region. Pediatr Neurosurg 1997;26:17–24. 2. Anzai T, Kato I, Shirane R, Ogawa A, Yoshimoto T. [A case of diastematomyelia with meningomyelocele.] No Shinkei Geka 1992;20:261–5 (Jpn). 3. Emura T, Asashima M, Hasgizume K. An experimental animal model of split cord malformation. Pediatr Neurosurg 2000;33:283–92. 4. Ersahin Y, Demitras E, Mutluer S, Tosun AR, Saydam S. Split cord malformations: report of three unusual cases. Pediatr Neurosurg 1996;24:155–9.
Surg Neurol 409 2002;58:406 –9
5. Ersahin Y, Mutlur S, Kokaman S, Demitras E. Split cord malformation in children. J Neurosurg 1998;88:57– 65. 6. Katoh M, Hida K, Iwasaki Y, Koyanagi I, Abe H. A split cord malformation. Childs Nerv Syst 1998;14:398 – 400. 7. Koyama S, Sekido K, Yamaguchi K. [Two cases of diastematomyelia: its evaluation with MR imaging.] No Shinkei Geka 1989;17:393– 8 (Jpn). 8. Kumar R, Bansal KK, Chhabra DK. Split cord malformation (SCM) in paediatric patients. Neurol India 2001;49:128 –33. 9. Pang D. Split cord malformation: Part II: Clinical syndrome. Neurosurgery 1992;31:481–500. 10. Pang D, Dias MS, Ahab-Barmada M. Split cord malformation: Part I: a unified theory of embryogenesis for double spinal cord malformation. Neurosurgery 1992; 31:451– 80. 11. Prasad VS, Senger RL, Sahu BP, Immaneni D. Diastematomyelia in adults. Modern imaging and operative treatment. Clin Imaging 1995;19:270 – 4. 12. Totori-Donati P, Rossi A, Cama A. Spinal dysraphism: a review of neurological features with embryological correlations and proposal for a new classification. Neuroradiology 2000;42:471–91. COMMENTARY
Sato et al report an uncommon case of split cord malformation. The patient was a newborn who was born with a multiple myelomeningocele sacs, at L2 and S1, with unilateral lower limb weakness (asymmetric motor involvement). MRI showed two hemicords below the level of T5, which share the same meninges. Three-dimensional CT showed extensive vertebral anomalies as well. The myelomeningocele was repaired the next day. The authors found that MRI and 3D CT provided useful information for surgical planning. The MRI provided a good-quality view of the deranged anatomy of the hemicords, hydromyelia, and Type II split cord malformation. Three-dimensional CT added information about the bony anomalies. it has been a valuable addition to our practice as well. As the authors point out, a low-lying spinal cord is not necessarily the same as a tethered cord, although these terms have been used interchangeably. Resection of the septum is not always the first-line treatment, as least in newborns. The authors state that the rostral sac was a meningocele. In my experience, what may appear to be a meningocele on MRI always retains some neural elements or fibers—a pure meningocele is extremely rare. I congratulate the authors on their excellent surgical planning and good results. Yoon S. Hahn, M.D. Department of Neurosurgery University of Illinois at Chicago Chicago, Illinois