Intracranial infantile hemangioma - rare entity and common pitfalls: A comprehensive multidisciplinary approach from Neurosurgery, Neurooncology and Neuropathology.

OBJECTIVE: To review the rare entity of pediatric intracranial hemangiomas and discuss surgical pitfalls and pathophysiology in regard to cerebral edema formation. MATERIALS AND METHODS: We describe an extremely rare case of intracranial infantile hemangioma in a neonate with massive cerebral edema, surgically resected urgently because of acute herniation. We review the literature of 46 other pediatric cases of intracranial hemangioma, including congenital capillary hemangiomas. We analyze the data on age, sex distribution, tumor location, growth pattern, edema formation, histopathology, treatment, and outcome. RESULTS: Isolated intracranial infantile hemangiomas in the neonatal period are extremely rare. Some but not all hemangiomas can be treated pharmacologically. Extensive cerebral edema is a frequent finding and can become an enormous problem at surgical resection. The pathogenesis of the edema formation in hemangiomas is complex and is yet not well understood. CONCLUSION: Surgical resection of intracranial hemangiomas is associated with a high morbidity, and pharmacological treatment should, if possible, always be considered first, at least for preoperative optimization. The severity of cerebral edema varies among intracranial hemangiomas, which may be an indicator of different molecular properties of the individual lesions. This implies that further sub-classification of intracranial hemangiomas may be necessary.

New surgical paradigm for open neural tube defects.

INTRODUCTION: An open neural tube defect (ONTD) features an exposed, unclosed neural plate in the form of an expanded, flat, and frequently hefty neural placode. Traditional philosophy of ONTD repair aims at preserving function at any cost, which often means stuffing the entire thick and unwieldy but non-functional placode into a tight dural sac, increasing the likelihood of future tethering of the spinal cord. The same philosophy of attempting to save the whole perimetry of the placode also sometimes leads to inadvertent inclusion of parts of the squamous epithelial membrane surrounding the placode into the reconstructed product, only to form inclusion dermoid cyst causing further injury to the neural tissues. Lastly, defective closure of the caudal primary neural tube usually results in abolition of secondary and junctional neurulation, leaving a defective conus and sacral nerve roots, clinically presenting in most cases with neurogenic bladder and bowel dysfunction. Preserving this trapped but locally active sacral micturition center, isolated from suprasegmental inhibitory moderation, leads to a spastic, hyperactive, low compliance, and high-pressure bladder predisposing to upstream kidney damage, without benefits of normal bladder function. METHOD AND MATERIAL: We report the post-natal surgical treatment of 8 newborn infants with ONTD, in which we resected the non-functional portion of the neural placode identified as such by direct spinal cord/placode and nerve root stimulation, as well as by transcortical evoked motor responses to check for suprasegmental corticospinal connectivity. Any part of the placode without local function or upstream connections was resected, and the small caudal spinal cord stump closed with pia-to-pia microsutures. The patients were followed for pre- and post-operative neuro-urological status and with serial magnetic resonance imaging (MRI) at 3 weeks, 6 months, and 2 years post-repair. Follow-up period ranged from birth to 3 years (mean of 24 months). RESULTS: Of the 8 patients analyzed, 7 had a terminal and one a segmental ONTD. Pre-operative neurological level ranged from L4 to S2. Applying our new surgical paradigm, we found no neurological worsening post-operatively. All patients had a neurogenic bladder and bowel dysfunction but none had a high-pressure bladder on urodynamics studies. Early and late MRIs all showed a loose and capacious neural placode to dural sac relationship. None had an inclusion dermoid cyst. CONCLUSION: We propose a new paradigm for the surgical repair of open neural tube defects with intraoperative neuromonitoring and introduce a safe and reliable technique of placode debulking.

The Pantheon Variant of the Classic Cathedral Dome Procedure for Parieto-Occipital Skull Deformities.

OBJECTIVE: To describe a new technique for the reconstruction of parieto-occipital skull deformities. METHODS AND RESULTS: The technique is a variant of the previously described "cathedral dome procedure" used for frontal skull deformities. The authors apply the same principle of remodeling by making meridional slat craniotomies surrounding the depressed dome of the posterior skull deformity, followed by "green-stick fracture-reshaping" of the meridional slats to elevate and support the excised depressed dome. The authors present an illustrative patient with a follow-up of 2 years and an excellent cosmetic result. CONCLUSION: The authors introduce a new operative technique for the reconstruction of parieto-occipital skull deformities with excellent long-term results. The freshly reconstructed occiput resembles the dome of the pantheon in Rome, Italy, whose unique features inspired us to name this procedure the "Pantheon" variant of the cathedral dome operation.

Traumatic Posterior Fossa Subdural Hygroma and Secondary Occlusive Hydrocephalus.

BACKGROUND: Infratentorial subdural hygromas causing secondary occlusive hydrocephalus are extremely rare in children. Only a handful of cases have been reported in the literature. METHODS: We present a case of a 6-month-old infant with an occipital fracture and slow enlargement of a posterior fossa subdural hygroma that culminated in obstructive hydrocephalus. We give a review of the literature on post-traumatic posterior fossa hygroma with secondary occlusive hydrocephalus and discuss its pathogenesis and the mechanism of its later resolution, as well as the available treatment options. RESULTS: A temporary external ventricular drain led to acute relief of the hydrocephalus and subsequent complete resolution of the subdural hygroma. CONCLUSION: Temporary external ventricular drain placement led to complete resolution of the subdural hygroma and hydrocephalus. We recommend close clinical follow-up, and imaging if indicated, for as long as 4 weeks after trauma with occipital skull fractures.

Limited dorsal myeloschisis associated with dermoid elements.

INTRODUCTION: Limited dorsal myeloschisis (LDM) originates from undisjointed neural and cutaneous ectoderms during primary neurulation. Its hallmark is a fibroneural stalk causing tethering on the dorsal spinal cord rostral to the conus. Its treatment is a relatively straightforward resection of the LDM stalk from the spinal cord. METHODS AND RESULTS: On reviewing our series of 75 cases of LDMs, we found that the majority of LDM stalks have only a glioneuronal core within a fibrous stroma, but a small number have been found to have elements of dermoid cyst or a complete dermal sinus tract either contiguous with the fibroneural stalk or incorporated within its glial matrix, not surprising considering the original continuum of cutaneous and neural ectoderm in LDMs' embryogenesis. The dermoid element can be microscopic and escape casual observation, but could grow to large intradural dermoid cysts if part of the dermoid invested LDM stalk is left inside the dura. CONCLUSIONS: We present our series of LDMs associated with dermoid elements and recommend excising the entire length of the intradural LDM stalk from its dural entry point to its merge point with the spinal cord during the initial treatment to avoid secondary deterioration and additional surgery.

Use of intraoperative lateral pelvic X-ray to localize and ensure coccyx removal during sacrococcygeal teratoma resection.

En bloc removal of the coccyx during sacrococcygeal teratoma resection is necessary to decrease the risk of recurrence. However, variable anatomy often makes the border between the coccyx and sacrum difficult to identify. We describe the use of intraoperative lateral pelvic X-ray to localize this border and ensure complete coccygectomy.

Unjoined primary and secondary neural tubes: junctional neural tube defect, a new form of spinal dysraphism caused by disturbance of junctional neurulation.

INTRODUCTION: Primary and secondary neurulation are the two known processes that form the central neuraxis of vertebrates. Human phenotypes of neural tube defects (NTDs) mostly fall into two corresponding categories consistent with the two types of developmental sequence: primary NTD features an open skin defect, an exposed, unclosed neural plate (hence an open neural tube defect, or ONTD), and an unformed or poorly formed secondary neural tube, and secondary NTD with no skin abnormality (hence a closed NTD) and a malformed conus caudal to a well-developed primary neural tube. METHODS AND RESULTS: We encountered three cases of a previously unrecorded form of spinal dysraphism in which the primary and secondary neural tubes are individually formed but are physically separated far apart and functionally disconnected from each other. One patient was operated on, in whom both the lumbosacral spinal cord from primary neurulation and the conus from secondary neurulation are each anatomically complete and endowed with functioning segmental motor roots tested by intraoperative triggered electromyography and direct spinal cord stimulation. The remarkable feature is that the two neural tubes are unjoined except by a functionally inert, probably non-neural band. CONCLUSION: The developmental error of this peculiar malformation probably occurs during the critical transition between the end of primary and the beginning of secondary neurulation, in a stage aptly called junctional neurulation. We describe the current knowledge concerning junctional neurulation and speculate on the embryogenesis of this new class of spinal dysraphism, which we call junctional neural tube defect.

Isolated unilateral rupture of the alar ligament.

Only 6 cases of isolated unilateral rupture of the alar ligament have been previously reported. The authors report a new case and review the literature, morbid anatomy, and pathogenesis of this rare injury. The patient in their case, a 9-year-old girl, fell head first from a height of 5 feet off the ground. She presented with neck pain, a leftward head tilt, and severe limitation of right rotation, extension, and right lateral flexion of the neck. Plain radiographs and CT revealed no fracture but a shift of the dens toward the right lateral mass of C-1. Magnetic resonance imaging of the cervical spine showed signal hyperintensity within the left dens-atlas space on both T1- and T2-weighted sequences and interruption of the expected dark signal representing the left alar ligament, suggestive of its rupture. After 12 weeks of immobilization in a Guilford brace, MRI showed lessened dens deviation, and the patient attained full and painless neck motion. Including the patient in this case, the 7 patients with this injury were between 5 and 21 years old, sustained the injury in traffic accidents or falls, presented with marked neck pain, and were treated with external immobilization. All patients had good clinical outcome. The mechanism of injury is hyperflexion with rotation. Isolated unilateral alar ligament rupture is a diagnosis made by excluding associated fracture, dislocation, or disruption of other major ligamentous structures in the craniovertebral junction. CT and MRI are essential in establishing the diagnosis. External immobilization is adequate treatment.

Traumatic rupture of the neurocentral synchondrosis of the axis in a child.

The authors report the first case of unilateral traumatic rupture of the C-2 neurocentral synchondrosis. A 26-month-old child was in a vehicular collision that caused his head to be rotated sharply to the left with the neck flexed. He had severe neck pain but was neurologically normal. Computerized tomography scanning showed rupture of the left C-2 neurocentral synchondrosis, a right C-2 pars interarticularis fracture, and anterior angulation of C-2 on C-3. The neck injury was unrecognized until postinjury Day 9 when an MRI study showed a tear of the posterior longitudinal ligament at C2-3 and separation of the C-2 body from the inferior anular epiphysis. A second CT showed widening of the synchondrosis fracture, increased angulation of C-2 on C-3, and distraction of the right C-2 pars fracture. The mechanism of the neurocentral synchondrosis fracture is thought to be hyperflexion-axial loading combined with leftward rotation, which provided the lateral force that overcame the cartilaginous synchondrosis and extruded the lateral mass. The patient underwent open reduction and posterior fusion of C1-3, and was maintained in a halo jacket for 4 months, when CT scans demonstrated solid C1-C3 fusion and ossification of the injured synchondrosis. Unilateral traumatic rupture of the C-2 neurocentral synchondrosis is one component of several injuries involving C-2 sustained before synchondrosis closure. The resulting C2-3 relationship is highly unstable. Reduction and C1-C3 fusion are necessary in patients with significant displacement of the adjacent bony units.

Innervation of the brain, intracerebral Schwann cells and intracerebral and intraventricular schwannomas.

The cerebral vasculature and the choroid plexus are innervated by peripheral nerves. The anatomy of the vascular supply to the brain and its related perivascular nerves is reviewed. Intracerebral and intraventricular schwannomas most likely come from neoplastic transformation of Schwann cells investing the perivascular nerves and nerves within the choroid plexus.

Limited dorsal myeloschisis: a not-so-rare form of primary neurulation defect.

PURPOSE: Limited dorsal myeloschisis (LDM) is a distinctive form of spinal dysraphism characterized by two constant features: a focal "closed" midline skin defect and a fibroneural stalk that links the skin lesion to the underlying cord. The embryogenesis is hypothesized to be incomplete disjunction between cutaneous and neural ectoderms, thus preventing complete midline skin closure and allowing persistence of a physical link (fibroneural stalk) between the disjunction site and the dorsal neural tube. OBJECTIVE: We utilize the experience gained from the management of 63 patients with LDM to illustrate these features. METHODS: All patients were studied with MRI or CT myelogram, operated on, and followed for a mean of 9.4 years. RESULTS: There were 11 cervical, 16 thoracic, 8 thoracolumbar, and 28 lumbar lesions. Two main types of skin lesion were: saccular (26 patients; consisting of a skin base cerebrospinal fluid sac topped with squamous epithelial dome or a thin membranous sac) and nonsaccular (37 patients; with a flat or sunken squamous epithelial crater or pit). The internal structure of a saccular LDM could be a basal neural nodule, a stalk that inserts on the dome, or a segmental myelocystocoele. In nonsaccular LDMs, the fibroneural stalk has variable thickness and complexity. All fibroneural stalks contain glioneuronal tissues accompanied by variable quantities of nerves and mesodermal derivatives. In all LDMs, the fibroneural stalk was tethering the cord. Twenty-nine patients had neurological deficits. There was a positive correlation between neurological grade and age suggesting progression with chronicity. Treatment consisted of detaching the stalk from the cord. Most patients improved or remained stable. LDMs were associated with three other dysraphic malformations in more than coincidental frequencies: six LDMs were contiguous with dorsal lipomas, four LDMs shared the same tract or traveled in parallel with a dermal sinus tract, and seven LDMs were related to a split cord malformation. The embryogenetic implications of these associations are discussed. CONCLUSION: LDM is a distinctive clinicopathological entity and a tethering lesion with characteristic external and internal features. We propose a new classification incorporating both saccular and flat lesions.

Surgical treatment of complex spinal cord lipomas.

PURPOSE: This paper shows the long-term benefits of total/near-total resection of complex spinal cord lipomas and meticulous reconstruction of the neural placode, and specifically, its advantage over partial resection, and over non-surgical treatment for the subset of children with asymptomatic virgin lipomas. METHODS: The technique of total resection and placode reconstruction, together with technical nuances, are described in detail. We added 77 patients with complex lipomas to our original lipoma series published in 2009 and 2010, to a total of 315 patients who had had total or near-total resection and followed for a span of 20 years. Long-term outcome is measured by overall progression-free survival (PFS) with the Kaplan-Meier analysis, and by subgroup Cox proportional recurrence hazard analysis for the influence on outcome of 4 predictor variables of lipoma type, presence of symptoms, prior surgery, and post-operative cord-sac ratio. These results are compared to an age-matched, lesion-matched series of 116 patients who underwent partial lipoma resection over 11 years. The results for total resection is also compared to two large published series of asymptomatic lipomas followed without surgery over 9 to 10 years, to determine whether prophylactic total resection confers better long-term protection over conservative treatment for children with asymptomatic lipomas.. RESULTS: The PFS after total resection for all lipoma types and clinical subgroups is 88.1 % over 20 years versus 34.6 % for partial resection at 10.5 years (p < 0.0001). Culling only the asymptomatic patients with virgin (previously unoperated) lipomas, the PFS for prophylactic total resection for this subgroup rose to 98.8 % over 20 years, versus 67 % at 9 years for one group of non-surgical treatment and 60 % at 10 years for another group of conservative treatment. Our own as well as other published results of partial resection also compare poorly to non-surgical treatment for the subset of asymptomatic virgin lipomas. Multivariate subgroup analyses show that cord-sac ratio is the only independent variable that predicts outcome, with a 96.9 % PFS for ratio < 30 % (loosest sac), 86.2 % for ratio between 30 and 50 %, and 78.3 % for ratio > 50 % (tightest sac), and a threefold increase in recurrence hazard for high ratios (p = 0.0009). Pre-operative patient profiling using multiple correspondence analysis shows the ideal patient for total resection is a child less than 2 years old with a virgin asymptomatic lipoma, who, with a PFS of 99.2 %, is virtually cured by total resection. CONCLUSION: Total/near-total resection of complex lipomas and complete reconstruction of the neural placode achieves far better long-term protection against symptomatic recurrence than partial resection for all lesions; and for the subset of asymptomatic virgin lipomas, also better than non-surgical treatment. Partial resection in many cases produces worse outcome than conservative treatment for asymptomatic lesions.

Parallel angulated frontal bone slat cuts for treatment of metopic synostosis and other frontal skull deformities: the "cathedral dome procedure".

PURPOSE: This study aims to describe a new procedure for the treatment of metopic synostosis and other frontal skull deformities. METHOD: The procedure comprises a supraorbital bandeau widened with an interpositional graft and rounded laterally to eliminate the acute angle, and parallel angulated slat cuts in the frontal bones. Greenstick fracturing of the medial bases of these slats along a parasagittal hinge line causes fanning of the slats and expansion of the frontal flap both anteriorly and laterally making the forehead contour wider and more rounded. We performed this procedure on six infants (four with severe trigonocephaly from metopic synostosis, one with brachycephaly from bicoronal synostosis, and one with multiple suture synostosis and parietal flattening) for whom only the angulated slat cuts (without bandeau) were used. Each patient had preoperative three-dimensional computed tomography (3D-CT) and postoperative 3D-CT at 1 week, 3 months, and 12 months, to follow the result. RESULT: The cosmetic improvements are dramatic in eliminating the midfrontal keel, hypotelorism, frontal-lateral retrusion, and temporal hollowing seen in severe metopic synostosis. In coronal synostosis, the procedure corrects the brachycephaly and gives a balanced, well-rounded frontal contour. The end results of the fronto-orbital correction resemble the ribbed dome of a cathedral; hence, the moniker the "cathedral dome procedure". No patient needed a second procedure to fill in cranial defects or recorrect deficient areas. CONCLUSION: The parallel angulated frontal slat cuts technique (the "cathedral dome procedure") is a straightforward and easily mastered method that reliably produces excellent result for the correction of trigonocephaly and other frontal skull deformities.

Terminal myelocystocele: surgical observations and theory of embryogenesis.

BACKGROUND: The structural complexity of terminal myelocystocele (TMC) precludes a recognizable link to spinal cord development and therefore a plausible embryogenetic theory. OBJECTIVE: To demystify TMC using clinical, imaging, surgical, electrophysiological, and histopathological data and to propose a theory of embryogenesis. METHODS: Our series consisted of 4 newborns and 6 older children. All had preoperative magnetic resonance imagings and surgical repair of the myelocystocele with electrophysiological monitoring. RESULTS: TMC can be deconstructed into essential and nonessential features. Essential features are present in all TMCs and constitute the core malformation, comprising an elongated spinal cord extending extraspinally into a cerebrospinal fluid--filled cyst that is broadly adherent to the subcutaneous fat. The functional conus resides in the proximal cyst or within the intraspinal cord, and the caudal myelocystocele wall is nonfunctional fibroneural tissue. Nonessential features include variable measures of hydromyelia, caudal meningocele, and fat, present in only some patients. The core structure of TMC strikingly resembles a transitory stage of late secondary neurulation in chicks in which the cerebrospinal fluid-filled bleblike distal neural tube bulges dorsally to fuse with the surface ectoderm, before focal apoptosis detaches it from the surface and undertakes its final dissolution. We theorize that TMC results from a time-specific paralysis of apoptosis just before the dehiscence of the cystic distal cord from the future skin, thereby preserving the embryonic state. CONCLUSION: Besides tethering, the myelocystocele may show early rapid expansion causing precipitous deterioration. We recommend early repair with resection of the nonfunctional caudal cyst wall, reconstruction of the proximal neural placode, and duraplasty.

Retained medullary cord in humans: late arrest of secondary neurulation.

BACKGROUND: Formation of the caudal spinal cord in vertebrates is by secondary neurulation, which begins with mesenchyme-epithelium transformation within a pluripotential blastema called the tail bud or caudal cell mass, from thence initiating an event sequence proceeding from the condensation of mesenchyme into a solid medullary cord, intrachordal lumen formation, to eventual partial degeneration of the cavitatory medullary cord until, in human and tailless mammals, only the conus and filum remain. OBJECTIVE: We describe a secondary neurulation malformation probably representing an undegenerated medullary cord that causes tethered cord symptoms. METHOD: We present 7 patients with a robust elongated neural structure continuous from the conus and extending to the dural cul-de-sac, complete with issuing nerve roots, which, except in 2 infants, produced neurological deficits by tethering. RESULTS: Intraoperative motor root and direct cord stimulation indicated that a large portion of this stout neural structure was "redundant" nonfunctional spinal cord below the true conus. Histopathology of the redundant cord resected at surgery showed a glioneuronal core with ependyma-lined lumen, nerve roots, and dorsal root ganglia, corroborating the picture of a blighted spinal cord. CONCLUSION: We propose that these redundant spinal cords are portions of the medullary cord normally destined to regress but are here retained because of late arrest of secondary neurulation before the degenerative phase. Because programmed cell death almost certainly plays a central role during degeneration, defective apoptosis may be the underlying mechanism.

Limited dorsal myeloschisis: a distinctive clinicopathological entity.

BACKGROUND: Limited dorsal myeloschisis (LDM) is a distinctive form of spinal dysraphism characterized by 2 constant features: a focal "closed" midline defect and a fibroneural stalk that links the skin lesion to the underlying cord. The embryogenesis is hypothesized to be incomplete disjunction between cutaneous and neural ectoderms, thus preventing complete midline skin closure and allowing persistence of a physical link (fibroneural stalk) between the disjunction site and the dorsal neural tube. OBJECTIVE: To illustrate these features in 51 LDM patients. METHODS: All patients were studied with magnetic resonance imaging or computed tomography myelography, operated on, and followed for a mean of 7.4 years. RESULTS: There were 10 cervical, 13 thoracic, 6 thoracolumbar and 22 lumbar lesions. Two main types of skin lesion were saccular (21 patients), consisting of a skin-base cerebrospinal fluid sac topped with a squamous epithelial dome, and nonsaccular (30 patients), with a flat or sunken squamous epithelial crater or pit. The internal structure of a saccular LDM could be a basal neural nodule, a stalk that inserts on the dome, or a segmental myelocystocele. In nonsaccular LDMs, the fibroneural stalk has variable thickness and complexity. In all LDMs, the fibroneural stalk was tethering the cord. Twenty-nine patients had neurological deficits. There was a positive correlation between neurological grade and age, suggesting progression with chronicity. Treatment consisted of detaching the stalk from the cord. Most patients improved or remained stable. CONCLUSION: LDM is a distinctive clinicopathological entity and a tethering lesion with characteristic external and internal features. We propose a new classification incorporating both saccular and flat lesions.

Long-term outcome of total and near-total resection of spinal cord lipomas and radical reconstruction of the neural placode, part II: outcome analysis and preoperative profiling.

OBJECTIVE: To show the long-term benefits of total and near-total resection of complex spinal cord lipomas and reconstruction of the neural placode. METHODS: We analyzed 238 patients with dorsal, transitional, and chaotic lipomas who had total resection as described in part I for overall progression-free survival probability (PFS, Kaplan-Meier analysis) over 16 years. We also analyzed subgroup proportional recurrence hazard (Cox analysis) of 6 outcome predictors of sex, lipoma type, age, preoperative symptoms, previous surgery, and postoperative cord-sac ratio. These results were compared with an age-matched, lesion-matched series of 116 patients followed for 11 years after partial lipoma resection and with the Parisian series of nonsurgical treatment. RESULTS: The immediate effects of surgery were similar between total and partial resection: both achieved greater than 95% symptom stabilization or improvement rate. The neuro-urologic complication rates for the groups were also similar, 4.2% and 5.2% for total and partial resection, respectively. The combined cerebrospinal fluid leakage and wound complication rate of total resection was much lower at 2.5% than the 6.9% for partial resection, but both were better than published rates. The overall PFS for total resection was 82.8% at 16 years, comparing much more favorably with 34.6% for partial resection at 10.5 years (P < .0001). Culling only the asymptomatic patients with virgin (previously unoperated) lipomas to match the patient profile of the Parisian series, the PFS for prophylactic total resection for this subgroup increased to 98.4% at 16 years, versus 67% at 9 years for no surgery and 43.3% at 10.5 years for our own partial resection series, with a remarkable statistical difference between total and partial resection (P = .00001). Subgroup analyses showed that sex and lipoma type did not affect outcome. For the other predictor variables, while univariate analyses showed that young age, absence of symptom, and virgin lipomas correlated with better statistical PFS than older age, symptoms, and redo lipomas, these effects vanished with multivariate analyses. Cord-sac ratio stood alone as the only influential outcome predictor in multivariate analysis, with a 96.6% PFS for a low ratio of <30% and an 80.6% progression-free probability for a high ratio of >50%, and a 3-fold increase in recurrence hazard for high ratios (P = .0009). This suggested that all the individual effects of the other predictor variables could be reduced to whether a low cord-sac ratio could be achieved with total lipoma resection and placode reconstruction. Cord-sac ratio was the obvious factor that differentiated the outcomes between total and partial resection, the latter associated with a >90% chance of having a high cord-sac ratio. CONCLUSION: Total and near-total resection of lipomas and complete reconstruction of the neural placode produced a much better long-term progression-free probability than partial resection and nonsurgical treatment. The perioperative complications for total resection were low and compared favorably with published results. A low postoperative cord-sac ratio and well-executed placode neurulation were strongly correlated with good outcome. The ideal preoperative patient profile with early disease stabilization and the best recurrence-free probability is an asymptomatic child less than 2 years without previous lipoma surgery. There are strong indications that partial resection in many cases produces worse scarring on the neural placode and worse prognosis than no surgery.

Long-term outcome of total and near-total resection of spinal cord lipomas and radical reconstruction of the neural placode: part I-surgical technique.

OBJECTIVE: Partial resection of complex spinal cord lipomas is associated with a high rate of symptomatic recurrence caused by retethering, presumably promoted by a tight content-container relationship between the spinal cord and the dural sac, and incomplete detachment of the terminal neural placode from residual lipoma. Since 1991, we have performed more than 250 total/near-total resections of complex lipomas with radical reconstruction of the neural placodes. Sixteen years of follow-up have proven the long-term benefits of this technique. Part I of this series introduces our technique of total resection and reports the immediate surgical results. Part II will analyze the long-term outcomes of both total and partial resection and identify the factors affecting outcome. METHODS: From 1991 to 2006, 238 patients (age range, 2 months-72 years) with dorsal, transitional, and chaotic lipomas underwent total or near-total lipoma resection and radical placode reconstruction. Eighty-four percent of the patients were children younger than 18 years and 16% were adults. The technique consisted of wide bony exposure, complete unhinging of the lateral adhesions of the lipoma-placode assembly from the inner dura, untethering of the terminal conus, radical resection of the fat off the neural plate along a white fibrous plane at the cord-lipoma interface, meticulous pia-to-pia neurulation of the supple neural placode with microsutures, and expansile duraplasty with a bovine pericardial graft. Elaborate electrophysiological monitoring was used. RESULTS: Three postoperative observations concern us. The first is that of the 238 patients, 138 (58%) had no residual fat on postoperative magnetic resonance imaging; 81 patients (36%) had less than 20 mm3 of residual fat, the majority of which were small bits enclosed by neurulation; and 19 patients (8%), mainly of the chaotic lipoma group, had more than 20 mm of fat. There are no significant differences in the amount of residual fat among lipoma types, but redo lipomas are more likely than virgin (previously unoperated on) lipomas to have residual fat by a factor of 2 (P = 0.0214). The second concern is that the state of the reconstructed placode is objectively measured by the cord-sac ratio, obtained by dividing the sagittal diameter of the reconstructed neural tube by the sagittal diameter of the thecal sac. A total of 162 patients (68%) had cord-sac ratios less than 30% (low), 61 (25.6%) had ratios between 30% and 50% (medium), and only 15 (6.3%) had high ratios of more than 50%. Seventy-four percent of patients with virgin lipomas had low cord-sac ratios compared with 56.3% in the redo lipoma patients. The overall distribution of cord-sac ratio is significantly different between redo and virgin lipomas (P = 0.00376) but not among lipoma types. Finally, the incidence of combined neurological and urological complications was 4.2%. The combined cerebrospinal fluid leak and wound infection/dehiscence incidence was 2.5%. Both sets of surgical morbidity compared favorably with the published rates reported for partial resection. CONCLUSION: Total/near-total resection of spinal cord lipomas and complete reconstruction of the neural placode can be achieved with low surgical morbidity and a high yield of agreeable postoperative cord-sac relationship. Some large rambling transitional lipomas and most chaotic lipomas are the most difficult lesions to resect and tend to have less favorable results on postresection magnetic resonance imaging.

Atlanto-occipital dislocation--part 2: The clinical use of (occipital) condyle-C1 interval, comparison with other diagnostic methods, and the manifestation, management, and outcome of atlanto-occipital dislocation in children.

OBJECTIVE: The diagnosis of atlanto-occipital dislocation (AOD) remains problematic as a result of a lack of reliable radiodiagnostic criteria. In Part 1 of the AOD series, we showed that the normal occiput-C1 joint in children has an extremely narrow joint gap (condyle-C1 interval [CCI]) with great left-right symmetry. In Part 2, we used a CCI of 4 mm or greater measured on reformatted computed tomographic (CT) scans as the indicator for AOD and tested the diagnostic sensitivity and specificity of CCI against published criteria. The clinical manifestation, neuroimaging findings, management, and outcome of our series of patients with AOD are also reported. METHOD: For diagnostic sensitivity, we applied the CCI criterion on 16 patients who fulfilled one or more accepted radiodiagnostic criteria of AOD and who showed clinical and imaging hallmarks of the syndrome. All 16 patients had plain cervical spine x-rays, head CT scans, axial cervical spine CT scans with reconstruction, and magnetic resonance imaging scans. The diagnostic yield and false-negative rate of CCI were compared with those of four published "standard" tests, namely Wholey's dens-basion interval, Powers' ratio, Harris' basion-axis interval, and Sun's interspinous ratio. The diagnostic value of "nonstandard" indicators such as cervicomedullary deficits, tectorial membrane and other ligamentous damage, perimedullary subarachnoid hemorrhage, and extra-axial blood at C1-C2 were also assessed. For diagnostic specificity, we applied CCI and the "standard" and "nonstandard" tests on 10 patients from five classes of non-AOD upper cervical injuries. The false-positive diagnostic rates for AOD of all respective tests were documented. RESULTS: The CCI criterion was positive in all 16 patients with AOD with a diagnostic sensitivity of 100%. Fourteen patients had bilateral AOD with disruption and widening of both OC1 joints. Two patients had unilateral AOD with only one joint wider than 4 mm. The abnormal CCI varied from 5 to 34 mm. Eight patients showed blatant left-right joint asymmetry in either CCI or anatomic conformation. The diagnostic sensitivities for the "standard" tests are as follows: Wholey's, 50%; Powers', 37.5%; Harris', 31%; and Sun's, 25%, with false-negative rates of 50, 62.5, 69, and 75%, respectively. The sensitivities for the "nonstandard" indicators are: tectorial membrane damage, 71%; perimedullary blood, 63%; and C1-C2 extra-axial blood, 75%, with false-negative rates of 29, 37, and 25%, respectively. Fifteen patients with AOD had occiput-cervical fusion. There were one early and two delayed deaths (19% mortality); two patients (12%) had complete or severe residual high quadriplegia, but 11 children (69%) enjoyed excellent neurological recovery. CCI was normal in all 10 patients with non-AOD upper cervical injuries with a diagnostic specificity of 100%. The false-positive rates for the four "standard" tests were: Sun's, 60%; Harris', 50%; Wholey's, 30%; and Powers', 10%; for the "nonstandard" indicator, the rates were: cervicomedullary deficits, 70%; tectorial membrane damage, 40%; C1-C2 extra-axial blood, 40%; and perimedullary blood, 30%. CONCLUSION: The CCI criterion has the highest diagnostic sensitivity and specificity for AOD among all other radiodiagnostic criteria and indicators. CCI is easily computed from reconstructed CT scans, has almost no logistical or technical distortions, can capture occiput-C1 joint dislocation in all three planes, and is unaffected by congenital anomalies or maturation changes of adjacent structures. Because CCI is the only test that directly measures the integrity of the actual joint injured in AOD and a widened CCI cannot be concealed by postinjury changes in the head and neck relationship, it surpasses others that use changeable landmarks.