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Segmental spinal cord hypoplasia and meningocele with preservation of medullary function: case report
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Segmental Spinal Cord Hypoplasia and Meningocele with Preservation of Medullary Function: Case Report Geert Buyse, M.D.,*† Frank Van Calenbergh, M.D.,* Maurice Choux, M.D., Ph.D.,‡ Philippe Demaerel, M.D., Ph.D.,§ Raf Sciot, M.D., PhD.,¶ and Carla Verpoorten, M.D.㛳 *Departments of Neurosurgery, §Radiology, ¶Neuropathology, and 㛳Paediatrics, University Hospital Gasthuisberg, Catholic University of Leuven, Leuven, Belgium; †Department of Neurosurgery, General Hospital Damiaan, Oostende, Belgium; ‡Department of Paediatric Neurosurgery, Ho ˆpital des Enfants de la Timone, Marseille, France
Buyse G, Van Calenbergh F, Choux M, Demaerel P, Sciot R, Verpoorten C. Segmental spinal cord hypoplasia and meningocele with preservation of medullary function: case report. Surg Neurol 2003;59:505– 8.
report an unusual case, where the hypothetical primary defect remains unclear.
BACKGROUND
In very rare dysraphic cases, it is not clear whether the primary abnormalities are in the neural elements, or in the bony elements. CASE DESCRIPTION
We describe a case of segmental hypoplasia of the spinal cord, with absent nerve roots in the afflicted segments, and associated meningocele and vertebral abnormalities. We illustrate the arguments for and against the classification of this lesion either as an atypical case of myelomeningocele (MMC) or as a mild case of segmental spinal dysgenesis (SSD). CONCLUSION
Possibly, in this exceptional case, the primary defect is in the neural tissue like in more usual cases of MMC and not in the spine, like in segmental spinal dysgenesis. © 2003 Elsevier Inc. All rights reserved. KEY WORDS
Segmental spinal dysgenesis, segmental spinal cord hypoplasia, myelomeningocele.
n dysraphic lesions it can be very difficult to determine whether the primary defect lies in the bone or in the nerve tissue. For myelomeningocele, it is generally accepted that the failure of the neural tube to close is the primum movens, while in the Chiari I malformation, recent findings prove the posterior fossa bony elements to be the cause. We
I
Address reprint requests to: Prof. Dr. Frank Van Calenbergh, Department of Neurosurgery, University Hospital Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium. Received November 8, 2001; accepted January 7, 2003. © 2003 Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010 –1710
Case Report A 2-day-old-boy with hydrocephalus and a thoracic occult spina bifida was referred to our university hospital. The pregnancy and delivery had been uncomplicated. On clinical examination we observed a dorsal swelling, with normal overlying skin. There were signs of raised intracranial pressure. Ultrasonography, X-ray, and magnetic resonance imaging (MRI) of the spine revealed a meningocele, extending from T4 to T7. Most remarkable was a segmental hypoplasia of the spinal cord, lying in the right anterolateral region of the spinal canal, and without exiting nerve roots. There was a mild sinistroconvex scoliosis, hypoplasia of vertebral bodies T6-7-8 with reduction of antero-posterior length and secondary mild kyphosis. Computed tomography (CT) and MRI of the skull demonstrated hydrocephalus, partial agenesis of the corpus callosum and Chiari type 1 malformation. The dysraphic lesion was treated conservatively, because there was no neurologic deficit and only a mild kyphoscoliosis. A ventriculoperitoneal shunt was implanted. A regular follow-up, including clinical examination, somatosensory evoked potentials and urodynamic examination was performed. No abnormalities were found. At 6 years, the boy complained more and more of 0090-3019/03/$–see front matter doi:10.1016/S0090-3019(03)00067-3
506 Surg Neurol 2003;59:505– 8
Buyse et al
MRI axial T2-weighted image: meningocele, important medullary hypoplasia, premedullary cyst, absence of posterior vertebral elements. The spinal cord is localized in the right anterolateral region.
2
MRI sagittal T1-weighted image revealing a midthoracic meningocele with segmental medullary and hypoplasia of vertebral bodies T6-7-8, leading to scoliosis and some kyphosis.
1
interscapular swelling, mostly when sitting against the back of a chair. He was also ashamed to participate in sport activities. The neurologic examination remained completely normal. New imaging studies (Figures 1–3) showed no progression of the kyphoscoliosis. The midthoracic meningocele, with segmental medullary hypoplasia, remained comparable, but now there was a small premedullary arachnoid cyst. There was also a small cervical syrinx. An operative exploration was performed to realize the following objectives: relief of the subjective complaints, esthetic considerations, marsupialization of the premedullary cyst, and if necessary untethering. The skin and underlying fat were excised in an oval shape. After opening the dura, we noticed minor arachnoid adhesions, leading to minimal tethering of the myelon. Adhesiolysis was performed
and the premedullary arachnoid cyst was marsupialized. Over 3 segments, the spinal cord proved to be very hypoplastic, with absence of all nerve roots, but with a normal median posterior fissure. The meningocele was excised and the dura was closed in a watertight fashion. Histologic examination of the meningocele showed that the wall of the cyst consisted of meningothelial tissue. The postoperative course was uncomplicated. After 2 years, the child remains asymptomatic.
Discussion The dysraphic anomaly in this patient is extremely unusual and very difficult to classify. There was a segmental hypoplasia of the spinal cord, with absence of nerve roots in three segments, but apparently normal long tracts and neurologic function. There were associated bony abnormalities, with both spina bifida (failure of laminae closure) and vertebral body hypoplasia and scoliosis. Furthermore, several brain abnormalities (partial agenesis of the corpus callosum, hydrocephalus, and tonsillar herniation) were seen. Because of this, and the relatively minor bony anomalies, one can hypothesize that the primary defect has occurred in the neural elements. From this point of view, this exceptional case resembles the cervical myelomeningoceles described by Pang [4]. However, in all those
Segmental Spinal Cord Hypoplasia
Surg Neurol 507 2003;59:505– 8
bral translation, spinal canal stenosis, and rib anomalies. Most of the 27 patients in the literature had paraparesis or paraplegia and a neurogenic bladder; but nine patients initially had a normal neurologic status. Most of the patients had lower limb deformities: flexion and abduction of the hip joints, flexion of the knee joints and equinocavovarus deformity of the feet. Many associated anomalies have been reported: horseshoe kidneys and renal ectopia, situs transversus, tetralogia of Fallot, dislocation of the radial head, imperforate anus, rectovaginal fistula, hypoplasia of the lungs, Sprengel deformity, torticollis, deafness, and hypoplasia of the thumbs. Our case shares some features with SDD. However, in SDD, the primary abnormalities are in the vertebral elements, leading to a dysgenesis and obliteration of the spinal canal and secondary atrophy of the spinal cord, while in our case the spinal canal was wide. Therefore, there was no indication for decompression [2,3], and the mild kyphoscoliosis will only be surgically treated in case of progression.
Conclusion 3
Spinal radiograph abnormalities.
illustrating
the
bony
cases the meningocystocele sac always contained glial and neural tissue (dorsal roots and ganglia) and there were neurologic symptoms and spinal cord tethering. In our patient the sac only contained meningothelial tissue and the child was neurologically normal. Also the presence of a posterior median fissure in our case is not completely compatible with the cases described by Pang. An alternative hypothesis would be to classify this lesion as an atypical form of segmental spinal dysgenesis (SSD). This syndrome was defined by Scott et al [5] as a segmental dysgenesis of the spine, segmental atrophy of the underlying spinal cord and nerve roots, congenital paraparesis, and lower limb deformities. So far, only two large series [1,6] have been published. These described other frequent radiographic findings, such as an enlarged and low-lying medullary conus, associated occult spina bifida (above, at or below the SSD), diastematomyelia, thickened filum terminale, dermal sinus, split notochord syndrome, terminal myelocystocele, aplastic or hypoplastic vertebral bodies, hemiand butterfly vertebrae, kyphosis, scoliosis, verte-
Our case seems to defy classification in one of the known syndromes and cannot be included in SDD, nor in the previously published types of myelomeningocele. A primary disturbance in the development of the neural tissue seems probable, rather than a bony problem. The authors thank Dr. Dachling Pang, M.D., F.R.C.S., F.A.C.S. for his interesting comments on this unusual case.
REFERENCES 1. Faciszewski T, Winter RB, Lonstein JE, Sane S, Erickson D. Segmental spinal dysgenesis. A disorder different from spinal agenesis. J Bone Joint Surg (Am.) 1995;77: 530 –7. 2. Flynn JM, Otsuka NY, Emans JB, Haal JE, Hresko MT. Segmental spinal dysgenesis: early neurologic deterioration and treatment. J Pediatr Orthop 1997;17:100 –4. 3. Hughes LO, McCarthy RE, Glasier CM. Segmental spinal dysgenesis: a report of three cases. J Pediat Orthop 1998;17:227–32. 4. Pang D, Dias MS. Cervical myelomeningocele. Neurosurgery 1993;33:363–73. 5. Scott RM, Wolpert SM, Barthoshesky LE, Zimbler S, Karlin L. Segmental spinal dysgenesis. Neurosurgery 1988;22:739 –44. 6. Tortori-Donati P, Fondelli MP, Rossi A, Raybaud CA, Cama A, Capra V. Segmental spinal dysgenesis: neuroradiological findings with clinical and embryologic correlation. AJNR 1999;20:445–56.
Segmental Spinal Cord Hypoplasia and Meningocele with Preservation of Medullary Function: Case Report Geert Buyse, M.D.,*† Frank Van Calenbergh, M.D.,* Maurice Choux, M.D., Ph.D.,‡ Philippe Demaerel, M.D., Ph.D.,§ Raf Sciot, M.D., PhD.,¶ and Carla Verpoorten, M.D.㛳 *Departments of Neurosurgery, §Radiology, ¶Neuropathology, and 㛳Paediatrics, University Hospital Gasthuisberg, Catholic University of Leuven, Leuven, Belgium; †Department of Neurosurgery, General Hospital Damiaan, Oostende, Belgium; ‡Department of Paediatric Neurosurgery, Ho ˆpital des Enfants de la Timone, Marseille, France
Buyse G, Van Calenbergh F, Choux M, Demaerel P, Sciot R, Verpoorten C. Segmental spinal cord hypoplasia and meningocele with preservation of medullary function: case report. Surg Neurol 2003;59:505– 8.
report an unusual case, where the hypothetical primary defect remains unclear.
BACKGROUND
In very rare dysraphic cases, it is not clear whether the primary abnormalities are in the neural elements, or in the bony elements. CASE DESCRIPTION
We describe a case of segmental hypoplasia of the spinal cord, with absent nerve roots in the afflicted segments, and associated meningocele and vertebral abnormalities. We illustrate the arguments for and against the classification of this lesion either as an atypical case of myelomeningocele (MMC) or as a mild case of segmental spinal dysgenesis (SSD). CONCLUSION
Possibly, in this exceptional case, the primary defect is in the neural tissue like in more usual cases of MMC and not in the spine, like in segmental spinal dysgenesis. © 2003 Elsevier Inc. All rights reserved. KEY WORDS
Segmental spinal dysgenesis, segmental spinal cord hypoplasia, myelomeningocele.
n dysraphic lesions it can be very difficult to determine whether the primary defect lies in the bone or in the nerve tissue. For myelomeningocele, it is generally accepted that the failure of the neural tube to close is the primum movens, while in the Chiari I malformation, recent findings prove the posterior fossa bony elements to be the cause. We
I
Address reprint requests to: Prof. Dr. Frank Van Calenbergh, Department of Neurosurgery, University Hospital Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium. Received November 8, 2001; accepted January 7, 2003. © 2003 Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010 –1710
Case Report A 2-day-old-boy with hydrocephalus and a thoracic occult spina bifida was referred to our university hospital. The pregnancy and delivery had been uncomplicated. On clinical examination we observed a dorsal swelling, with normal overlying skin. There were signs of raised intracranial pressure. Ultrasonography, X-ray, and magnetic resonance imaging (MRI) of the spine revealed a meningocele, extending from T4 to T7. Most remarkable was a segmental hypoplasia of the spinal cord, lying in the right anterolateral region of the spinal canal, and without exiting nerve roots. There was a mild sinistroconvex scoliosis, hypoplasia of vertebral bodies T6-7-8 with reduction of antero-posterior length and secondary mild kyphosis. Computed tomography (CT) and MRI of the skull demonstrated hydrocephalus, partial agenesis of the corpus callosum and Chiari type 1 malformation. The dysraphic lesion was treated conservatively, because there was no neurologic deficit and only a mild kyphoscoliosis. A ventriculoperitoneal shunt was implanted. A regular follow-up, including clinical examination, somatosensory evoked potentials and urodynamic examination was performed. No abnormalities were found. At 6 years, the boy complained more and more of 0090-3019/03/$–see front matter doi:10.1016/S0090-3019(03)00067-3
506 Surg Neurol 2003;59:505– 8
Buyse et al
MRI axial T2-weighted image: meningocele, important medullary hypoplasia, premedullary cyst, absence of posterior vertebral elements. The spinal cord is localized in the right anterolateral region.
2
MRI sagittal T1-weighted image revealing a midthoracic meningocele with segmental medullary and hypoplasia of vertebral bodies T6-7-8, leading to scoliosis and some kyphosis.
1
interscapular swelling, mostly when sitting against the back of a chair. He was also ashamed to participate in sport activities. The neurologic examination remained completely normal. New imaging studies (Figures 1–3) showed no progression of the kyphoscoliosis. The midthoracic meningocele, with segmental medullary hypoplasia, remained comparable, but now there was a small premedullary arachnoid cyst. There was also a small cervical syrinx. An operative exploration was performed to realize the following objectives: relief of the subjective complaints, esthetic considerations, marsupialization of the premedullary cyst, and if necessary untethering. The skin and underlying fat were excised in an oval shape. After opening the dura, we noticed minor arachnoid adhesions, leading to minimal tethering of the myelon. Adhesiolysis was performed
and the premedullary arachnoid cyst was marsupialized. Over 3 segments, the spinal cord proved to be very hypoplastic, with absence of all nerve roots, but with a normal median posterior fissure. The meningocele was excised and the dura was closed in a watertight fashion. Histologic examination of the meningocele showed that the wall of the cyst consisted of meningothelial tissue. The postoperative course was uncomplicated. After 2 years, the child remains asymptomatic.
Discussion The dysraphic anomaly in this patient is extremely unusual and very difficult to classify. There was a segmental hypoplasia of the spinal cord, with absence of nerve roots in three segments, but apparently normal long tracts and neurologic function. There were associated bony abnormalities, with both spina bifida (failure of laminae closure) and vertebral body hypoplasia and scoliosis. Furthermore, several brain abnormalities (partial agenesis of the corpus callosum, hydrocephalus, and tonsillar herniation) were seen. Because of this, and the relatively minor bony anomalies, one can hypothesize that the primary defect has occurred in the neural elements. From this point of view, this exceptional case resembles the cervical myelomeningoceles described by Pang [4]. However, in all those
Segmental Spinal Cord Hypoplasia
Surg Neurol 507 2003;59:505– 8
bral translation, spinal canal stenosis, and rib anomalies. Most of the 27 patients in the literature had paraparesis or paraplegia and a neurogenic bladder; but nine patients initially had a normal neurologic status. Most of the patients had lower limb deformities: flexion and abduction of the hip joints, flexion of the knee joints and equinocavovarus deformity of the feet. Many associated anomalies have been reported: horseshoe kidneys and renal ectopia, situs transversus, tetralogia of Fallot, dislocation of the radial head, imperforate anus, rectovaginal fistula, hypoplasia of the lungs, Sprengel deformity, torticollis, deafness, and hypoplasia of the thumbs. Our case shares some features with SDD. However, in SDD, the primary abnormalities are in the vertebral elements, leading to a dysgenesis and obliteration of the spinal canal and secondary atrophy of the spinal cord, while in our case the spinal canal was wide. Therefore, there was no indication for decompression [2,3], and the mild kyphoscoliosis will only be surgically treated in case of progression.
Conclusion 3
Spinal radiograph abnormalities.
illustrating
the
bony
cases the meningocystocele sac always contained glial and neural tissue (dorsal roots and ganglia) and there were neurologic symptoms and spinal cord tethering. In our patient the sac only contained meningothelial tissue and the child was neurologically normal. Also the presence of a posterior median fissure in our case is not completely compatible with the cases described by Pang. An alternative hypothesis would be to classify this lesion as an atypical form of segmental spinal dysgenesis (SSD). This syndrome was defined by Scott et al [5] as a segmental dysgenesis of the spine, segmental atrophy of the underlying spinal cord and nerve roots, congenital paraparesis, and lower limb deformities. So far, only two large series [1,6] have been published. These described other frequent radiographic findings, such as an enlarged and low-lying medullary conus, associated occult spina bifida (above, at or below the SSD), diastematomyelia, thickened filum terminale, dermal sinus, split notochord syndrome, terminal myelocystocele, aplastic or hypoplastic vertebral bodies, hemiand butterfly vertebrae, kyphosis, scoliosis, verte-
Our case seems to defy classification in one of the known syndromes and cannot be included in SDD, nor in the previously published types of myelomeningocele. A primary disturbance in the development of the neural tissue seems probable, rather than a bony problem. The authors thank Dr. Dachling Pang, M.D., F.R.C.S., F.A.C.S. for his interesting comments on this unusual case.
REFERENCES 1. Faciszewski T, Winter RB, Lonstein JE, Sane S, Erickson D. Segmental spinal dysgenesis. A disorder different from spinal agenesis. J Bone Joint Surg (Am.) 1995;77: 530 –7. 2. Flynn JM, Otsuka NY, Emans JB, Haal JE, Hresko MT. Segmental spinal dysgenesis: early neurologic deterioration and treatment. J Pediatr Orthop 1997;17:100 –4. 3. Hughes LO, McCarthy RE, Glasier CM. Segmental spinal dysgenesis: a report of three cases. J Pediat Orthop 1998;17:227–32. 4. Pang D, Dias MS. Cervical myelomeningocele. Neurosurgery 1993;33:363–73. 5. Scott RM, Wolpert SM, Barthoshesky LE, Zimbler S, Karlin L. Segmental spinal dysgenesis. Neurosurgery 1988;22:739 –44. 6. Tortori-Donati P, Fondelli MP, Rossi A, Raybaud CA, Cama A, Capra V. Segmental spinal dysgenesis: neuroradiological findings with clinical and embryologic correlation. AJNR 1999;20:445–56.