Expanding Ventricular Diverticulum Overlying the Cerebral Hemisphere through an Open-Lip Schizencephalic Cleft: A Report of Two Pediatric Cases.

INTRODUCTION: Open-lip-type schizencephaly is characterized by trans-cerebral clefts filled with cerebrospinal fluid (CSF) between the subarachnoid space at the hemisphere surface and the lateral ventricles. Disorders related to CSF retention, including hydrocephalus and arachnoid cysts, have reportedly been associated with open-lip schizencephaly and have induced intracranial hypertension in some cases. However, detailed neuroimaging and surgical treatment findings have rarely been described. CASE PRESENTATION: We report 2 cases of open-lip schizencephaly with an expanding CSF-filled cavity overlying the ipsilateral cerebral hemisphere that manifested as signs of intracranial hypertension. Detailed three-dimensional heavily T2-weighted imaging revealed thin borders between the CSF-filled cavity and the subarachnoid space, but no separating structures between the cavity and the lateral ventricle, suggesting that the cavity was directly connected to the lateral ventricle through the schizencephalic cleft but not to the subarachnoid space. Neuroendoscopic observation in case 1 confirmed this finding. Endoscopic fenestration of the cavity to the prepontine cistern was ineffective in case 1. Shunting between the lateral ventricle (case 1) or CSF-filled cavity (case 2) and the peritoneal cavity slightly decreased the size of the CSF-filled cavity. DISCUSSION: We speculate that the thin borders along the margin of the CSF-filled cavity are membranes that previously covered the schizencephalic cleft and are now pushed peripherally. In addition, we believe that the cavity is a ventricular diverticulum protruding through the cleft and that shunting operation is effective against such expanding cavity. Detailed magnetic resonance imaging can be useful for evaluating patients with schizencephaly associated with CSF retention disorders.

Retained Medullary Cord Associated with Terminal Myelocystocele and Intramedullary Arachnoid Cyst.

INTRODUCTION: The retained medullary cord (RMC) is a newly defined entity of closed spinal dysraphism that is thought to originate from regression failure of the medullary cord during the last phase of secondary neurulation. The terminal myelocystocele (TMC) is an unusual type of closed spinal dysraphism, characterized by localized cystic dilatation of the terminal part of the central canal that then herniates through a posterior spinal bifida. The co-occurrence of RMC and TMC is extremely rare. CASE PRESENTATION: We treated a baby girl with a huge sacrococcygeal meningocele-like sac with two components. Untethering surgery and repair surgery for the sac revealed that RMC, associated with intramedullary arachnoid cyst (IMAC), was terminated at the bottom of the rostral cyst, forming the septum of the two cystic components, and the caudal cyst was TMC derived from the central canal-like ependymal lining lumen (CC-LELL) of the RMC at the septum. IMAC within the RMC communicated with TMC, and both contained xanthochromic fluid with the same properties. CONCLUSION: We speculated that the mass effect of the coexistent IMAC impeded the flow of cerebrospinal fluid in the CC-LELL within the RMC and eventually formed a huge TMC. In surgical strategies for such complex pathologies, it is important to identify the electrophysiological border between the functional cord and nonfunctional RMC and the severe RMC to untether the cord, as with a typical or simple RMC.

Retained medullary cord with sacral subcutaneous meningocele and congenital dermal sinus.

BACKGROUND: A retained medullary cord (RMC) is a rare closed spinal dysraphism with a robust elongated cord-like structure extending continuously from the conus medullaris to the dural cul-de-sac that is caused by late arrest of secondary neurulation. Five patients with RMC extending to an associated sacral subcutaneous meningocele have been reported. CASE PRESENTATION: We report an additional patient with RMC, in whom a congenital dermal sinus (CDS) was found in the caudal portion of the RMC. At the age of 3 days, the patient underwent surgery consisting of meningocele excision and cord untethering, and CDS was noted histologically in the proximal cut end of the RMC. During a second surgery at the age of 5 months, after determining the exact border of the nonfunctional RMC and the true conus by neurophysiological mapping, we removed the entire length of the remnant RMC, including newly developed epidermoid cysts in the CDS. CONCLUSION: Although the exact pathoembryogenesis of concurrent RMC and CDS is unknown, an associated subcutaneous meningocele, caused by failure of primary neurulation, could be involved. Surgeons should be aware of the possibility of the coexistence of CDS when dealing with RMCs that extend out to the extradural space.

Congenital interdural arachnoid cyst of the tentorium cerebelli.

BACKGROUND: Intracranial interdural cyst is a rare lesion. The exact pathophysiology of these cysts remains unknown. CLINICAL PRESENTATION: We report an infant with interdural cyst of the tentorium cerebelli. Although the cyst mimicked an arachnoid cyst on pre- and postnatal magnetic resonance images, lateral suboccipital craniotomy revealed the cyst within the tentorium. Fenestration on the infratentorial side was performed with successful results. Histologically, the inner surface of the cyst was lined with arachnoid cells. CONCLUSION: We report detailed neuroradiological, intraoperative, and histological findings, and discuss the pathophysiology of the cyst in this case.

Ruptured dermoid cyst of the conus medullaris in the myelomeningocele sac revealed at the initial repair surgery.

BACKGROUND: Dermoid cysts in the myelomeningocele (MMC) site are thought to arise in a delayed fashion because of iatrogenic implantation of dermoid elements at the time of the initial repair surgery. However, there have been few reports on dermoid elements already present at birth. CLINICAL PRESENTATION: We report a patient, in whom dermoid cyst was located at dorsal aspect of the conus medullaris in the MMC sac. Between 23+3 and 24+4 weeks of gestation, rupture of the MMC sac occurred. At this time of gestation, we speculate that rupture of the dermoid cyst also occurred and dissemination of the cyst contents caused chemical arachnoiditis in the MMC sac. At the age of 1 day, surgery to repair MMC and postoperative histological findings revealed these rare pathologies. CONCLUSION: Physicians should be aware of the possibility of rupture of a dermoid cyst in the MMC sac during fetal period.

Terminal syringomyelia associated with lumbar limited dorsal myeloschisis.

PURPOSE: Limited dorsal myeloschisis (LDM) is characterized by a fibroneural tethering stalk linking the skin lesion to the underlying spinal cord. Terminal syringomyelia, which is located at the lower third of the cord, is often associated with a tethered cord caused by various spinal dysraphisms; however, terminal syringomyelia has not been documented in LDM. The purpose of this study was to clarify the pathophysiological mechanisms of syringomyelia in LDM. METHODS: In our 16 patients with lumbar LDM, three patients had terminal syringomyelia. We retrospectively analyzed the clinical, neuroradiological, intraoperative, and histopathological findings for these patients, with particular attention to the clinical course of the syrinx. RESULTS: Patient 1 had a saccular skin lesion and patients 2 and 3 had flat lesions. In all patients, the syringomyelic cavity was located in the lower thoracolumbar cord, immediately rostral to the stalk-cord attachment at the lumbar level. The caudal pole of the syrinx extended to the thickened stalk at the attachment instead of at the caudal cord. Patient 3 had another syrinx in the stalk itself. The longitudinal axis of the syrinx and central canal coincided with the traveling angle of the LDM stalk at the stalk-cord attachment. In patient 1, histology revealed an ependyma-lined central canal in both the LDM stalk and meningocele sac. Patients 1 and 2 underwent syringostomy, but long-term effects were not obtained. Preoperative spontaneous resolution occurred in patient 3. CONCLUSIONS: The histological findings in patient 1 supported the idea that segmental myelocystocele is involved in the development of saccular LDM. The hydromyelic central canal herniates and distends the stalk, resulting in the formation of the myelocystocele. It is possible that the hydromyelic central canal also distends the stalk of flat LDM lesions. The syrinx in patient 3 differed from that in patients 1 and 2, in that the syrinx resolved spontaneously. Further studies are needed to clarify the outcomes of syrinxes associated with LDM stalks.

Congenital Dermal Sinus Elements in Each Tethering Stalk of Coexisting Thoracic Limited Dorsal Myeloschisis and Retained Medullary Cord.

INTRODUCTION: The embryogenesis of limited dorsal myeloschisis (LDM) likely involves impaired disjunction between the cutaneous and neural ectoderms during primary neurulation. Because LDM and congenital dermal sinus (CDS) have a shared origin in this regard, CDS elements can be found in the LDM stalk. Retained medullary cord (RMC) is a closed spinal dysraphism involving a robust, elongated, cord-like structure extending from the conus medullaris to the dural cul-de-sac. Because the RMC is assumed to be caused by impaired secondary neurulation, concurrent RMC and CDS cannot be explained embryologically. In the present article, we report a case in which CDS elements were noted in each tethering stalk of a coexisting LDM and RMC. CASE PRESENTATION: A 2.5-month-old boy with left clubfoot and frequent urinary and fecal leakage had 2 tethering tracts. The upper tract, which ran from the thoracic tail-like cutaneous appendage, had CDS elements in the extradural stalk and a tiny dermoid cyst in the intradural stalk immediately after the dural entry. In the lower tract, which ran from the lumbosacral dimple, the CDS as an extradural stalk continued to the RMC at the dural cul-de-sac. Both stalks were entirely resected through skip laminotomy/laminectomy at 1 stage to untether the cord and resect the CDS elements. CONCLUSION: Surgeons should be aware that CDS elements, in addition to LDM, may coexist with RMC that extends out to the extradural space.

Neurosurgical Pathology and Management of Limited Dorsal Myeloschisis Associated with Congenital Dermal Sinus in Infancy.

BACKGROUND: Because of the shared origin of limited dorsal myeloschisis (LDM) and congenital dermal sinus (CDS), CDS elements may be found within the fibroneural LDM stalk. When part of the CDS invested in the intradural stalk is left during untethering surgery, inclusion tumors such as dermoid cysts may develop. However, the most appropriate surgical strategy for LDM with CDS is still under debate. METHODS: Of 19 patients with LDM, 3 (15.8%) had histologically verified CDS elements. We retrospectively analyzed the clinicopathological findings of these patients. RESULTS: In patient 1, the entire stalk including a tiny dermoid cyst at the intradural stalk could be resected through two-level laminectomy during untethering at 6 months of age. In patients 2 and 3, the stalk appeared to be a typical LDM stalk during the initial surgery at 18 and 7 days, respectively; however, CDS was histologically diagnosed in the proximal severed end of the stalk. Postoperative three-dimensional heavily T2-weighted imaging demonstrated spherical enlargement of the remnant stalk, and the entire length of the remnant stalk including newly developed dermoid was resected during the second surgery at 3 years 11 months and 11 months, respectively. Histopathologically, glial fibrillary acidic protein-immunopositive neuroglial tissues and CDS elements were mainly located at the proximal and distal sites of the stalk, respectively, supporting the "dragging down and pulling up" theory. In patients 2 and 3, however, the proximal head of the dermoid cyst passed the distal head of the neuroglial tissues and located at the stalk-cord attachment. CONCLUSION: Surgeons should be aware of the approximately 10% possibility of the coexistence of CDS when managing infant LDM. However, the recommendation for excision of the entire length of the LDM stalk in all patients should be more carefully made because such a strategy may result in an unnecessary extent of laminotomy/laminectomy for most patients with pure LDM. However, once the postoperative histological examination reveals coexistence of CDS in the resected proximal part of the stalk, the entire length of the remnant stalk should be excised as soon as possible.

Subcortical axonal loss with glial reactions following partial status epilepticus with neuroradiological findings of reduced subcortical diffusion.

Hyperintensity in the subcortical white matter on the diffusion-weighted magnetic resonance image has been described recently, in association with partial status epilepticus. Although this reduced subcortical diffusion is typically seen in patients with acute encephalopathy with biphasic seizures and late reduced diffusion (AESD), the exact pathophysiological mechanism is unclear. We report the case of a 3-month-old boy who underwent surgery for intractable epilepsy associated with cortical dysplasia in the left peri-Rolandic area, coincident with the appearance of reduced subcortical diffusion. Neurohistological findings revealed that the most prominent finding was axonal loss with marked astroglial and microglial reactions in the white matter. Neither degenerated neurons nor neurophagocytic microglial accumulation was evident in the cortex. These findings confirm that white matter can be secondarily damaged in patients with partial status epilepticus, and possible pathomechanism of reduced subcortical diffusion is discussed.

Huge multiple spinal extradural meningeal cysts in infancy.

BACKGROUND: Multiple spinal extradural meningeal cysts (SEMCs) are rare lesions. SEMCs communicate with the subarachnoid space through multiple dural defects and expand into the extradural space with progressive spinal cord compression. CASE PRESENTATION: We report a 5-month-old boy with hydronephrosis involving nine huge SEMCs that were distributed from the T1-L5 levels. Eight SEMCs, except for one small noncommunicating cyst, were exposed through laminoplastic laminotomy at the T10-L5 and T3-5 levels. Five transdural communications with dural defects were packed with a piece of autologous muscle and fibrin glue. Tenting sutures to lift up the dura to the vertebral arch were added to minimize the extradural dead space. Postoperatively, cord compression was relieved and hydronephrosis improved. CONCLUSION: In conclusion, packing of all dural defects and dural tenting sutures at a one-staged operation is useful in the surgical management of huge and multiple SEMCs in infancy.

Correction to: Human tail-like cutaneous appendage with a contiguous stalk of limited dorsal myeloschisis.

The article was recently published, contained error. Author name "Nobutaka Mukai" should be "Nobutaka Mukae". Given in this article is the correct name.

Surgical histopathology of limited dorsal myeloschisis with flat skin lesion.

PURPOSE: Limited dorsal myeloschisis (LDM) is characterized by two invariable features: a focal closed neural tube defect and a fibroneural stalk linking the skin lesion to the underlying spinal cord. Although detailed histopathological findings of the LDM stalk were originally described by Pang et al., the precise relationship between the histopathological findings and clinical manifestations including intraoperative findings has not been fully determined. METHODS: We retrospectively analyzed the histopathological findings of the almost entire stalk and their relevance to the clinical manifestations in six Japanese LDM patients with flat skin lesions. RESULTS: Glial fibrillary acidic protein (GFAP)-immunopositive neuroglial tissues were observed in three of the six patients. Unlike neuroglial tissues, peripheral nerve fibers were observed in every stalk. In four patients, dermal melanocytosis, "Mongolian spot," was seen surrounding the cigarette-burn lesion. In three of these four patients, numerous melanocytes were distributed linearly along the long axis of the LDM stalk, which might represent migration of melanocytes from trunk neural crest cells during formation of the LDM stalk. CONCLUSION: Immunopositivity for GFAP in the LDM stalk was observed in as few as 50% of our patients, despite the relatively extensive histopathological examination. We confirm that the clinical diagnosis of LDM should be made based on comprehensive histopathological examination as well as clinical manifestations. The profuse network of peripheral nerve fibers in every stalk and the high incidence of melanocyte accumulation associated with dermal melanocytosis might assist the histopathological diagnosis of LDM.

Human tail-like cutaneous appendage with a contiguous stalk of limited dorsal myeloschisis.

PURPOSE: Limited dorsal myeloschisis (LDM) is characterized by a fibroneural stalk linking the skin lesion to the underlying spinal cord. On account of the external skin lesion, all LDMs are either flat (nonsaccular) or saccular, and a human tail-like cutaneous appendage has not been reported. METHODS: In our 14 LDM patients, 2 had tail-like appendages. We retrospectively analyzed the relationship between the appendage and the LDM tract from the clinicopathological findings of these 2 patients. RESULTS: Preoperative magnetic resonance imaging including three-dimensional heavily T2-weighted images demonstrated an intradural tethering tract, but failed to reveal the precise communication with the appendage. However, surgery revealed the extradural and intradural slender stalk, starting at the base of appendage and running through the myofascial defect. Histological examination demonstrated that there was a tight anatomical relationship between the fibroadipose tissue of the appendage and the fibrocollagenous LDM stalk. CONCLUSION: When there is potential for an LDM stalk in patients with an appendage, a meticulous exploration of the stalk leading from an appendage is required. Clinicians should be aware of possible morphological variations of skin lesions associated with LDM.

Slender Stalk with Combined Features of Saccular Limited Dorsal Myeloschisis and Congenital Dermal Sinus in a Neonate.

Limited dorsal myeloschisis (LDM) and congenital dermal sinus (CDS) originate from incomplete disjunction between the cutaneous and neural ectoderms. Some LDM stalks have been found to have elements of a CDS or dermoid cyst. We surgically treated a saccular lesion in the lumbosacral region of a 7-day-old male neonate. Although fetal magnetic resonance imaging (MRI) failed to reveal a stalk, postnatal MRI including three-dimensional heavily T2-weighted imaging demonstrated a stalk originating from the lumbar cord and extending caudally to enter the lumbosacral meningocele sac. During untethering surgery, we found that the stalk was slender, with a diameter of 0.7-0.8 mm, but otherwise appeared to be a typical LDM stalk. Histopathological examination revealed that the fibrocollagenous stalk contained glial fibrillary acidic protein-immunopositive neuroglial tissues and stratified squamous epithelium. The present report describes the first documented case of a stalk with combined features of saccular LDM and CDS in a neonate. Since cutaneous ectodermal tissue is likely to remain in the remnant stalk, this patient requires careful monitoring to detect the potential development of a dermoid cyst.

Dynamic morphological changes of thrombosed lateral sinus pericranii revealed by serial magnetic resonance images.

BACKGROUND: Sinus pericranii (SP) is a rare venous anomaly involving an abnormal connection of the intracranial dural sinuses with the extracranial veins. Magnetic resonance (MR) imaging (MRI) with MR venography can detect the typically congested intra- and extracranial venous components of SP. CLINICAL PRESENTATION: We report a rare case of lateral SP associated with the superior sagittal sinus, which might had already developed almost total thrombosis of the SP at the first MRI. As this patient had not presented with classical manifestations of SP on clinical or neuroradiological findings, the initial diagnosis of SP was difficult. Repeated MRI revealed dynamic morphological changes associated with reperfusion of the thrombosed SP via the cortical vein. CONCLUSION: MR venography combined with gadolinium enhancement was useful for diagnosis of the SP with an extremely slow flow status.

Limited dorsal myeloschisis with no extradural stalk linking to a flat skin lesion: a case report.

BACKGROUND: Limited dorsal myeloschisis (LDM) is characterized by a fibroneural stalk linking the skin lesion to the underlying spinal cord. CASE PRESENTATION : A 7-month-old girl with a lumbosacral "cigarette-burn" flat skin lesion underwent untethering surgery. The intradural tethering stalk appeared to originate at the dural wall and join the cord with no extradural stalk linking to the skin lesion. Histological examination of the intradural stalk revealed glial fibrillary acidic protein-immunopositive neuroglial tissues in the fibrocollagenous band, which is the central histopathological feature of an LDM stalk. CONCLUSION: It is conceivable that the LDM stalk in our patient was originally linked to the skin lesion and subsequently regressed and was replaced by mature adipose tissue. We should be mindful of possible variations in the morphological features of LDM.

Neurosurgical pathology of limited dorsal myeloschisis.

PURPOSE: The term limited dorsal myeloschisis (LDM) was used by Pang et al. (2010) to describe a distinct clinicopathological entity. LDMs are characterized by two invariable features: a focal-closed neural tube defect and a fibroneural stalk that links the skin lesion to the underlying spinal cord. METHODS: We retrospectively analyzed the neurosurgical pathologic findings of four LDM patients. RESULTS: Case 1 had a saccular skin lesion with nonterminal abortive myelocystocele at T11-12. Cases 2, 3, and 4 had a non-saccular (flat) skin lesion in the lumbosacral region. The morphologic features of the lesion in case 2 were those of meningocele manque. Cases 3 and 4 had accompanying non-LDM anomalies, caudal-type lipoma and type II split-cord malformation with neurenteric cyst, respectively. At preoperative diagnosis of the LDM stalk, magnetic resonance imaging, including 3D heavily T2-weighted image was useful; however, minute findings were often missed in the complicated cases 3 and 4. All patients had a favorable outcome following untethering of the stalk from the cord. The central histopathological feature of the LDM stalk is neuroglial tissue in the fibrocollagenous band; however, the stalk in cases 2 and 4 did not have glial fibrillary acidic protein-immunopositive neuroglial tissues. CONCLUSIONS: Therefore, the diagnosis of LDM should be made based on comprehensive evaluation of histologic and clinical findings.

Retained medullary cord extending to a sacral subcutaneous meningocele.

BACKGROUND: A retained medullary cord (RMC) is a rare closed spinal dysraphism with a robust elongated neural structure continuous from the conus and extending to the dural cul-de-sac. One case extending down to the base of a subcutaneous meningocele at the sacral level has been reported. CLINICAL PRESENTATION: We report on three cases of closed spinal dysraphism, in which a spinal cord-like tethering structure extended out from the dural cul-de-sac and terminated at a skin-covered meningocele sac in the sacrococcygeal region, which was well delineated in curvilinear coronal reconstructed images of 3D-heavily T2-weighted images (3D-hT2WI). Intraoperative neurophysiology revealed the spinal cord-like tethering structure was nonfunctional, and histopathology showed that it consisted of central nervous system tissue, consistent with RMC. The tethering structure histologically contained a glioneuronal core with an ependymal-like lumen and smooth muscle, which may indicate developmental failure during secondary neurulation. CONCLUSIONS: When the RMC extending to a meningocele is demonstrated with the detailed magnet resonance imaging including 3D-hT2WI, decision to cut the cord-like structure for untethering of the nervous tissue should be made under careful intraoperative neurophysiological monitoring.

Ependyma-Lined Canal with Surrounding Neuroglial Tissues in Lumbosacral Lipomatous Malformations: Relationship with Retained Medullary Cord.

BACKGROUND: An ependyma-lined canal with surrounding neuroglial tissues can be present in lumbosacral lipomatous malformations; however, the precise embryological significance is still unclear. METHOD: Six out of 50 patients with lipomatous malformations had ependymal structures. We retrospectively analyzed the clinical, neuroradiological, and histological findings of these patients to demonstrate the relationship with the embryological background of the retained medullary cord (RMC), which normally regresses, but was retained here because of late arrest of secondary neurulation. RESULTS: Five (13.9%) of 36 patients with filar and caudal types and 1 of 3 lipomyelomeningoceles had ependymal structures, while none with dorsal and transitional types had these tissues. Histologically, the ependymal structures surrounded by neuroglial tissue and containing various amounts of adipose tissue bear a striking resemblance to the ependymal structures in RMC. CONCLUSION: The 13.9% incidence of association between the ependymal structures and filar and caudal types is thought to be because of second ary neurulation failure with the same embryological background as that of RMC. Dorsal and transitional types, resulting from primary neurulation failure, therefore, did not have ependymal structures.

Bony and Cartilaginous Tissues in Lumbosacral Lipomas.

PURPOSE: It is well known that bony and cartilaginous tissues can be present in lumbosacral lipomas; however, the relationship between their presence and clinical features has not been demonstrated. METHODS: Five (10.4%) out of 48 patients had osteochondral tissues in lipomas. We retrospectively analyzed the clinical, neuroradiological, and histological findings of these patients. RESULTS: Five (45.5%) of 11 patients with dorsal and transitional type lipomas had osteochondral tissues, while none with caudal and filar type lipomas had these tissues. Presurgical imaging demonstrated that the osteochondral tissue was located in a large subcutaneous lipoma dorsal to the bifid vertebral column. Histologically, mature bone with hematopoietic marrow and hyaline cartilage were observed in 3 and 2 patients, respectively. CONCLUSIONS: The high incidence of association of osteochondral tissues with dorsal and transitional type lipomas is thought to be the result of primary neurulation failure with invasion of mesenchymal tissues. Caudal and filar type lipomas, resulting from secondary neurulation failure, thus did not have osteochondral tissue.