Long-Term Outcome of Total and Near-Total Resection of Spinal Cord Lipomas and Radical Reconstruction of the Neural Placode, Part II

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.

Elevated breast cancer risk among mothers of a population-based series of 2668 children with cancer

AIMS

Although a previous study found high risk of breast cancer in mothers of children with soft tissue sarcomas, breast cancer risks in mothers of sufferers of other childhood cancers largely remain unknown. The aetiology is not fully understood. The present study explored this excess by varying type of childhood solid cancer and formulated a hypothesis.

METHODS

Mothers of 2668 children with solid tumours included in the Manchester Children's Tumour Registry, 1954-96, were traced and followed up to 31 December 2000 through the UK National Health Service Central Register. Standardized incidence ratio (SIR), p-values and 95% confidence intervals were calculated from age and calendar-year-specific female breast cancer incidence rates for England and Wales.

RESULTS

There was a significant excess of breast cancer in mothers overall (SIR=1.3, 95%CI=1.0-1.5) mainly due to mothers of children with rhabdomyosarcoma (RMS) (SIR=2.2, 95%CI=1.0-4.0), skin cancer (SIR=7.9, 95%CI=2.9-17.1) and central nervous system tumours (SIR=1.2, 95%CI=0.9-1.8). Maternal breast cancer risk was associated with late age at birth of the index child, and male sex and young age at diagnosis in the index child. Risk was highest in the ten years, following the birth of the index. The pattern was seen most strongly in mothers of children with embryonal RMS.

CONCLUSION

There are excesses of breast cancer in mothers of children with solid tumours in general and specifically in RMS, skin and central nervous system (CNS). There appears to be a temporal relationship between certain tumours in children and breast cancer in their mothers, suggesting an origin of their respective pregnancy. We propose a mother-foetal interaction mechanism to explain this association.

ATLANTO-OCCIPITAL DISLOCATION—PART 2

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.

ATLANTO-OCCIPITAL DISLOCATION

OBJECTIVE

Although atlanto-occipital dislocation has long been recognized as an extremely unstable and often lethal injury, no single radiodiagnostic criterion published to date has achieved failure-proof status. This is because most existing diagnostic tests exploit bony landmarks remote from the injured condyle–C1 (OC1) joint so that patient positioning could inadvertently line up these landmarks and conceal actual disruption of the joint. Many of the landmarks used are wide apart and/or noncoplanar; their measurements are subject to errors related to x-ray angle, target–film distance, and superimposed bony outlines. We propose using the actual occipital condyle–C1 interval (CCI) obtained from high-resolution reconstructed computed tomographic scans as the indicator for OC1 joint disruption. We hypothesize that the normal CCI is very small and has great left-right symmetry and that atlanto-occipital dislocation is always manifested by an abnormal widening of the CCI and/or by left-right joint asymmetry irrespective of the shifting of other remote bony landmarks. Part I of this study establishes standard normal values for CCI in children.

METHOD

Sagittal and coronal reformatted images were obtained from thin axial computed tomographic scans performed on 89 children, 18 for nontraumatic complaints and 71 as part of a minor head trauma protocol but later exonerated for cervical injury. The interval between condyle and C1 was measured at four equidistant points on the joint surface on the sagittal and coronal images of all 178 joints (left and right) in the group. Sagittal and coronal CCIs are the means of four sagittal and four coronal measurements, respectively. The combined or true CCI for an individual joint was taken as the mean of both the sagittal and coronal (total of eight) measurements.

RESULTS

The mean combined CCI of all 178 joints was 1.28 mm ± 0.26 (standard deviation [SD]). None of the 178 CCIs exceeded 1.95 mm, and none of the individual joint interval measurements exceeded 2.5 mm. Left-right symmetry was tested by computing the mean left-right difference in CCI from all 89 subjects equal to 0.047 mm ± 0.002 (SD); or only 3% of the mean combined CCI. When the mean of all right CCIs (1.333 mm ± 0.31 SD) is contrasted with the mean of all left CCIs (1.327 mm ± 0.30 SD), the difference is 0.006 mm, or 1.09% of the mean total CCI (P = 0.792). Left-right symmetry is also apparent in conformational anatomy in both sagittal and coronal images. Linear regression analysis between CCI and age shows no statistical difference in CCI between age groups from 0.5 to 18 years. Linear regression performed separately on the right and left CCIs suggests that left-right symmetry is also stable through this age range.

CONCLUSION

The normal OC1 joint in children 0 to 18 years is tightly held together by ligaments with a mean CCI of 1.28 mm in the 89 subjects tested. There is great left–right joint symmetry in both CCI and conformational anatomy. CCI and left-right symmetry do not appear to change significantly with age. It is reasonable to set a maximum CCI as a discriminator between normal and disrupted OC1 joints to indicate atlanto-occipital dislocation.

Thoracoscopy for Correction of Adult Thoracic Scoliosis

The endoscopic technique of instrumentation, correction, and fusion for scoliosis has undergone radical modifications since the first surgery. Some key factors conducive to successful fusion, such as thorough discectomy and end plate removal, are common to endoscopic and non-endoscopic procedures. There are indeed special technical features in our endoscopic approach that clearly affect outcome, however, and their enumeration rightly chronicles the evolution of our experimental undertaking.

Atlantoaxial rotatory fixation: part 3-a prospective study of the clinical manifestation, diagnosis, management, and outcome of children with alantoaxial rotatory fixation

OBJECTIVE

This is a prospective study of the clinical manifestations, diagnostic motion analysis, management, and outcome of children with atlantoaxial rotatory fixation (AARF).

METHODS

Fifty children presenting with painful torticollis were subjected to the three-head positions diagnostic computed tomographic scanning protocol described in Part II of our AARF study. Twenty-nine children qualified as having AARF (8 Type I, 11 Type II, and 10 Type III), and six children were classified in the diagnostic gray zone (DGZ). The AARF patients were given either halter or calipers traction depending on the type and chronicity of pretreatment delay. Upon reduction, patients were immobilized with either a cervicothoracic brace or a halo. Recurrence of AARF on halo and patients whose deformity was not reducible were given posterior C1C2 fusion at the best achievable alignment. The difficulty and results of treatment were measured according to the following: duration of traction, number of reduction slippage, percent not reducible by traction, percent needing halo, percent needing fusion, total duration of treatment, total number of treatment procedures, and percent who lost normal C1C2 dynamics. Results were compared between groups stratified by AARF types, by chronicity of pretreatment delay (acute << 1 mo, subacute = 1-3 mo, chronic > or = 3 mo) and by the presence or absence of recurrence (recurrent AARF defined as having two or more slippages). DGZ patients were treated with only comfort measures for 2 weeks and then restudied. Only those children with persistent symptoms and DGZ or worse motion dynamics were given traction and bracing.

RESULTS

Neither age nor etiology significantly influenced the severity of AARF. There was only a slight tendency for children younger than 5 years, and for trauma, to associate with severe C1C2 interlock. Delay of treatment up to 11 months did not result in improvement of the neck restriction or in abatement of pain. In fact, there are strong suggestions that prolonged delay could lead to worsening of the rotatory dynamics: Type I AARF are highly correlated with delays longer than 3 months and Type III with delays less than 1 month. Also, four patients who had serial motion studies during the delay period showed clear worsening in the pathological stickiness in C1C2 rotation. In addition, chronic rotatory deformity led to progressive occiput -C1 separation or laxity teleologically to compensate for a skewed visual axis. The mean occiput -C1 separation angle for chronic patients was 31.2 degrees versus 5 degrees for acute patients and less than 3 degrees for normal children. The difficulty and duration of treatment, the number of reslippage after reduction, the rate of irreducibility, the need for halo and fusion, and the percentile of patients ultimately loosing normal C1C2 rotation were significantly greater with Type I patients than Type III patients, with Type II patients being intermediate. Likewise, chronic patients of all AARF types were much worse in all parameters than acute patients; subacute patients were closer to chronic patients in complexity and outcome. Severity and chronicity exerted independent effects on outcome, and the worse identifiable subgroup were the chronic Type I patients versus the best subgroup of acute Type III patients.Thirteen patients developed recurrent AARF; they had much worse prognosis in all aspects measured than nonrecurrent patients. Recurrence was adversely influenced by both the severity (type) and chronicity of AARF. Half of the DGZ patients resolved with analgesics, but two of six remained symptomatic and in DGZ dynamics, and one deteriorated to Type III AARF. Two of those three patients responded easily to traction and bracing, and one was lost to follow-up.

CONCLUSION

Children with painful torticollis should be subjected to the three-position computed tomographic diagnostic protocol, not only to secure the diagnosis of AARF but also to grade the severity of the condition by virtue of the dynamic motion curve. Closed reduction with traction should be instituted immediately to avoid the serious consequences of chronic AARF. Proper typing and reckoning of the pretreatment delay are requisites for selecting treatment modalities. Recurrent dislocation and incomplete reduction should be treated with posterior C1C2 fusion in the best achievable alignment. Open reduction and halo immobilization to avoid permanent fixation can be tried with select cases.

Atlantoaxial rotatory fixation: part 2--new diagnostic paradigm and a new classification based on motion analysis using computed tomographic imaging

OBJECTIVE

This is Part II of a study on atlantoaxial rotatory fixation (AARF) that aims to introduce a new diagnostic paradigm and a new classification of this condition based on motion analysis of C1C2 rotation using computed tomographic (CT) imaging. This phase of the study is possible because Part I succeeded in defining physiological C1C2 axial rotation with CT data from 21 normal children, displayed in a highly concordant composite motion curve, which is used as the normal template for the present study. AARF is defined as flagrant departure from normal motion dynamics as delineated by abnormal motion curves. The new classification is predicated on the graded amount of pathological stickiness in the restricted rotation.

METHODS

Forty children age 1.5 to 14 years with painful "cock-robin" necks resulting from minor trauma or otolaryngological procedures were subjected to 3 CT examinations: 1) in the presenting (P) position; 2) with the nose pointing up (P0 position); and 3) with the head forcefully turned to the opposite side as much as the patient could tolerate (P_ position). The angles made by C1 and C2 and the separation angle C1C2 degrees (C1 minus C2 degrees) were obtained as described in Part I. The test motion curve was generated by plotting C1 against C1C2 angles, and all motion curves were analyzed in the context of the normal template.

RESULTS

Five distinct groups with highly characteristic motion curves could be identified. Group 1 (n = 5) patients showed essentially unaltered ("locked") C1C2 coupled configurations regardless of corrective counterrotation, with curves that are horizontal lines in the upper two quadrants of the template. Group 2 (n = 7) patients had reduction of the C1C2 separation angle with forced correction, but C1 could not be made to cross C2. Their curves slope downward from right to left in the upper quadrants but never traverse the x axis. Group 3 (n = 9) patients showed C1C2 crossover, but only when the head was cranked far to the opposite side. Their motion curves traverse the x axis left of C1 = -20 degrees. Groups 1, 2, and 3 motion dynamics are respectively classified as Types I, II, and III AARF in descending degree of pathological stickiness, which is in essence a resistance against closure of the C1C2 angle to counterrotation. Group 4 (n = 14) patients had normal dynamics, and Group 5 (n = 5) patients showed motion curve features between normal and Type III AARF, designated as belonging to the diagnostic gray zone, an uncertain group that may or may not revert to normal dynamics with only comfort measures.

CONCLUSION

AARF can be reliably diagnosed with a simple and practical CT protocol and construction of a three-point motion curve superimposed on a reusable normal template. The type of AARF, reflective of the severity of pathological stickiness of rotation, can be identified readily by the shape of the motion curve. This system of classification is useful in selecting the best regimen of management.

AtlantoAxial Rotatory Fixation: Part 3—A Prospective Study of the Clinical Manifestation, Diagnosis, Management, and Outcome of Children with AlantoAxial Rotatory Fixation

OBJECTIVE:

This is a prospective study of the clinical manifestations, diagnostic motion analysis, management, and outcome of children with atlantoaxial rotatory fixation (AARF).

METHODS:

Fifty children presenting with painful torticollis were subjected to the three-head positions diagnostic computed tomographic scanning protocol described in Part II of our AARF study. Twenty-nine children qualified as having AARF (8 Type I, 11 Type II, and 10 Type III), and six children were classified in the diagnostic gray zone (DGZ). The AARF patients were given either halter or calipers traction depending on the type and chronicity of pretreatment delay. Upon reduction, patients were immobilized with either a cervicothoracic brace or a halo. Recurrence of AARF on halo and patients whose deformity was not reducible were given posterior C1C2 fusion at the best achievable alignment. The difficulty and results of treatment were measured according to the following: duration of traction, number of reduction slippage, percent not reducible by traction, percent needing halo, percent needing fusion, total duration of treatment, total number of treatment procedures, and percent who lost normal C1C2 dynamics. Results were compared between groups stratified by AARF types, by chronicity of pretreatment delay (acute ≪ 1 mo, subacute = 1–3 mo, chronic ≥ 3 mo) and by the presence or absence of recurrence (recurrent AARF defined as having two or more slippages). DGZ patients were treated with only comfort measures for 2 weeks and then restudied. Only those children with persistent symptoms and DGZ or worse motion dynamics were given traction and bracing.

RESULTS:

Neither age nor etiology significantly influenced the severity of AARF. There was only a slight tendency for children younger than 5 years, and for trauma, to associate with severe C1C2 interlock. Delay of treatment up to 11 months did not result in improvement of the neck restriction or in abatement of pain. In fact, there are strong suggestions that prolonged delay could lead to worsening of the rotatory dynamics: Type I AARF are highly correlated with delays longer than 3 months and Type III with delays less than 1 month. Also, four patients who had serial motion studies during the delay period showed clear worsening in the pathological stickiness in C1C2 rotation. In addition, chronic rotatory deformity led to progressive occiput −C1 separation or laxity teleologically to compensate for a skewed visual axis. The mean occiput −C1 separation angle for chronic patients was 31.2° versus 5° for acute patients and less than 3° for normal children. The difficulty and duration of treatment, the number of reslippage after reduction, the rate of irreducibility, the need for halo and fusion, and the percentile of patients ultimately loosing normal C1C2 rotation were significantly greater with Type I patients than Type III patients, with Type II patients being intermediate. Likewise, chronic patients of all AARF types were much worse in all parameters than acute patients; subacute patients were closer to chronic patients in complexity and outcome. Severity and chronicity exerted independent effects on outcome, and the worse identifiable subgroup were the chronic Type I patients versus the best subgroup of acute Type III patients.

Thirteen patients developed recurrent AARF; they had much worse prognosis in all aspects measured than nonrecurrent patients. Recurrence was adversely influenced by both the severity (type) and chronicity of AARF. Half of the DGZ patients resolved with analgesics, but two of six remained symptomatic and in DGZ dynamics, and one deteriorated to Type III AARF. Two of those three patients responded easily to traction and bracing, and one was lost to follow-up.

CONCLUSION:

Children with painful torticollis should be subjected to the three-position computed tomographic diagnostic protocol, not only to secure the diagnosis of AARF but also to grade the severity of the condition by virtue of the dynamic motion curve. Closed reduction with traction should be instituted immediately to avoid the serious consequences of chronic AARF. Proper typing and reckoning of the pretreatment delay are requisites for selecting treatment modalities. Recurrent dislocation and incomplete reduction should be treated with posterior C1C2 fusion in the best achievable alignment. Open reduction and halo immobilization to avoid permanent fixation can be tried with select cases.

Progressive cranial nerve palsy following shunt placement in an isolated fourth ventricle: case report

Cranial nerve palsy is rarely seen after shunt placement in an isolated fourth ventricle. In the few reports of this complication, neuropathies are thought to be caused by catheter injury to the brainstem nuclei either during the initial cannulations or after shrinkage of the fourth ventricle. The authors treated a child who suffered from delayed, progressive palsies of the sixth, seventh, 10th, and 12th cranial nerves several weeks after undergoing ventriculoperitoneal shunt placement in the fourth ventricle. Magnetic resonance imaging revealed the catheter tip to be placed well away from the ventricular floor but the brainstem had severely shifted backward, suggesting that the pathogenesis of the neuropathies was traction on the affected cranial nerves. The authors postulated that the siphoning effect of the shunt caused rapid collapse of the fourth ventricle and while the cerebellar hemispheres were tented back by adhesions to the dura, the brainstem became the only mobile component in response to the suction forces. Neurological recovery occurred after surgical opening of the closed fourth ventricle and lysis of the basal cistern adhesions, which restored moderate ventricular volume and released the brainstem to its normal position.

Clear cell meningioma: case report and review of the literature

Clear cell meningioma (CCM) is a rare variant of meningioma. Only 17 cases have been previously reported in children. Although it has bland cytologic features, it has a higher rate of recurrence than does conventional meningioma. This variant has been reported in sites such as spinal/intradural (lumbar and thoracic), cerebellopontine angle, and supratentorial. The differential diagnosis of CCM includes microcystic meningioma, hemangioblastoma, and clear cell ependymoma. The characteristic histology and immunohistochemistry leads to the diagnosis. We present a case of a 7-year-old boy with a CCM of the cauda equina and a review of pediatric CCM.

The combined use of hydroxyapatite and bioresorbable plates to repair cranial defects in children

OBJECT

Hydroxyapatite cement (HAC) is used with increasing frequency by craniofacial surgeons for building facial and skull base structures and by neurosurgeons for cranioplasty. Failures of HAC in cranioplasty have been attributed to breakage due to subjacent cerebrospinal fluid (CSF) pulsations through the dura mater. The authors describe a technique that involves inserting a resorbable MacroPore perforated plate to dampen CSF pulsations and then pouring HAC over the plate to fill a cranial defect and complete skull contouring.

METHODS

Fifteen children ranging in age from 2 to 9.5 years were included in the study; the size of the skull defects in these patients ranged from 6.25 to 42.5 cm2, with a mean of 20.65 cm2. Patients in whom the combined MacroPore--HAC devices were implanted underwent follow-up examinations that included serial skull radiography and computerized tomography scans. No fractures of the implants were demonstrated. At 6 months postsurgery, small fingerlings of new bone growth appeared in the underside of the HAC plate, probably spanning from the dura through perforations in the MacroPore plate. At intervals ranging from 18 months to 20 years after implantation, the gaps between cranial bone edges and that the HAC began to blur, culminating in the complete bonding of host bone with the margin of the HAC plate. All implants remained radiopaque and maintained size, thickness, and shape.

CONCLUSIONS

The findings of this study are promising and indicate that the combined use of HAC and a bioresorbable undercarriage that is osteoconductive, such as the MacroPore perforated plate, may produce a versatile and lasting cranioplasty in children.

Spinal Cord Injury without Radiographic Abnormality in Children, 2 Decades Later

OBJECTIVE:

Much new research has emerged since1982, when the original description of spinal cord injury without radiographic abnormality (SCIWORA) as a self-contained syndrome was reported. This article reviews new and old data on SCIWORA, from the past 2 decades.

METHODS:

This article reviews what we have learned since 1982 about the unique biomechanical properties of the juvenile spine, the mechanisms of injuries, the profound influence of age on injury pattern and outcome, the magnetic resonance imaging (MRI) features, and management algorithms of SCIWORA.

RESULTS:

The increasing use of MRI in SCIWORA has yielded ample evidence of damage in virtually all nonbony supporting tissues of the juvenile vertebral column, including rupture of the anterior and posterior longitudinal ligaments, intervertebral disc disruption, muscular and interspinal ligament tears, tectorial membrane rupture, and shearing of the subepiphyseal growth zone of the vertebral endplates. These findings provide the structural basis for the postulated “occult instability” in the spine of a patient after SCIWORA. MRI also demonstrated five classes of post-SCIWORA cord findings: complete transection, major hemorrhage, minor hemorrhage, edema only, and normal. These “neural” findings are highly predictive of outcome: patients with transection and major hemorrhage had profoundly poor outcome, but 40% with minor hemorrhage improved to mild grades, whereas 75% with “edema only” attained mild grades and 25% became normal. All patients with normal cord signals made complete recovery.

The large pool of clinical data from our own and other centers also lends statistical power to uphold most of our original assertions regarding incidence, causes of injury, pathophysiology, age-related changes in the malleability of the spine, vectors of deformation, and the extreme vulnerability of young children to severe cord injury, particularly high cervical cord injury. Thoracic SCIWORA has been identified as an important subset, comprising three subtypes involving high-speed direct impact, distraction from lap belts, and crush injury by slow moving vehicles. Computation of the sensitivities of MRI and somatosensory evoked potentials in detecting SCIWORA shows that both tests were normal in 12 to 15% of children with definite, persistent myelopathy; all of these children were nevertheless braced for 3 months because of their clinical syndrome. Children with transient deficits but abnormal MRI and/or somatosensory evoked potentials were also braced, but the 60% with transient deficits and normal MRI and somatosensory evoked potentials were not braced. This is a change from our original policy in 1982 of bracing all children with persistent or transient deficits, brought on by our new MRI and electrophysiology data.

CONCLUSION:

Injury prevention, prompt recognition, use of MRI and electrophysiological verification, and timely bracing of SCIWORA patients remain the chief measures to improve outcome.

Atlantoaxial rotatory fixation: Part 1--Biomechanics of normal rotation at the atlantoaxial joint in children

OBJECTIVE

Atlantoaxial rotatory fixation (AARF) remains a recondite entity loosely included under the panoply of cervical trauma. The difficulty in finding a precise definition and reliable diagnostic criteria for AARF has been chiefly because of a lack of normative biomechanical data for C1-C2 rotation. As Part 1 and foundation of a comprehensive undertaking to define the biomechanics, mechanism, diagnosis, classification, and management of AARF, the present study focuses on the dynamic behavior of C1 and C2 during normal voluntary head rotation in children.

METHODS

Twenty-one normal children 3 to 11.5 years old underwent computed tomographic examinations from the lower clivus to the base of C3 in various head positions during axial rotation. The angles made by C1, C2, and the occiput with the vertical 0 degrees were recorded, and from these, the separation angles between C1 and C2 (C1-C2 degrees) were calculated for each head position (represented by the C1 angle) studied. In 18 children, the range of rotation was between 90 and -90 degrees, i.e., with the head making a full 180-degree turn from one side to the other. In 3 children, the head was first turned from 0 to 90 degrees and then back from 90 to 0 degrees, making only a half turn. All separation angles (C1-C2 degrees) were then plotted against the corresponding C1 angle to create a motion curve, which, in essence, describes the interaction between C1 and C2 through the full range of head positions. In the 18 children with full turns, both individual motion curves and a composite motion curve comprising all data were constructed.

RESULTS

There is a high degree of concordance for rotational behavior of C1 and C2 in the 18 subjects undergoing full turn. C1 always crosses C2 at or near 0 degrees, the null point of full rotation. The predictable relationship between C1 and C2 is depicted by three distinct regions on the composite motion curve: when C1 rotates from 0 to 23 degrees, it moves alone, with C2 remaining stationary at approximately 0 degrees (the single-motion phase). When C1 rotates from 24 to 65 degrees, C1 and C2 move together, but C1 always moves at a faster rate (the double-motion phase), C2 being pulled by yoking ligaments. From 65 degrees onward, C1 and C2 move in exact unison (the unison-motion phase) with a fixed, maximum separation angle of approximately 43 degrees, head rotation being carried exclusively by the subaxial segments. In the 3 children with half turn, the forward rotation curve and the reverse rotation curve are almost superimposable, suggesting that the "yoking" between C1 and C2 is a result of more than just tensing and relaxing of ligaments but probably also to a mutual dragging by irregular bony surfaces between the two bones.

CONCLUSION

C1 and C2 in children move in a predictable manner during axial head rotation, with a high degree of concordance among subjects and a relatively narrow variance from the mean. The composite motion curve can thus be used as a touchstone against which may be judged all manners of pathological interlock or "stickiness" between C1 and C2 in rotation that could be defined as AARF.

Thoracoscopic techniques for the treatment of scoliosis

STUDY DESIGN

To determine the effectiveness of an endoscopic option in an anterior approach to the thoracolumbar spine for scoliosis treatment, 50 patients with follow-ups of 24-45 months were studied retrospectively.

OBJECTIVE

The objective was to develop a safe, reproducible, and effective endoscopic technique for the treatment of scoliosis that will provide equal or better outcomes compared with formal open surgical techniques. Techniques for endoscopic treatment of spinal disorders have been under development since 1993. The benefits of thoracoscopic surgery in treating spinal deformities have been documented as improved visualization of the spine, enhanced access to the extremes of the curve, decreased operative times and blood loss, shorter hospital stays and recuperative periods, and decreased overall costs. Following more than 150 endoscopic procedures for the treatment of these spinal deformities, the next progression was to develop a thoracoscopic technique of instrumentation, correction, and fusion for primary thoracic scoliosis. The goals are to gain comparable results, fusion rates, and degrees of correction that meet or exceed the current gold standards of an open procedure.

METHODS

From October 1996 to October 1998, 50 patients with a diagnosis of primary thoracic scoliosis were selected to undergo a thoracoscopic technique of instrumentation, correction, and fusion. Postoperatively, patients were assessed for restoration of spinal alignment, axial derotation, pain management, and incidence of complications. RESULTS. Successful endoscopic instrumentation occurred in all patients. Curve correction averaged 50.2%, improving to 68.6% in the last ten cases. Patients with hypokyphosis averaged 20.7 degrees of correction. The preoperative axial rotation, based on the scoliometer, averaged 16 degrees , which was corrected to 5 degrees postoperatively. Postoperative pain was less; patients were off all pain medication by 1-3 weeks compared with patients with a formal open procedure requiring pain medication for 6-12 weeks. The hospital stay averaged 2.9 days. Our initial complication rate was high, which can be attributed to the development of a new technique. The keys to successful fusions included total discectomy, complete endplate removal, and autogenous bone graft.

CONCLUSIONS

Although still in early development, the initial results of thoracoscopic techniques are promising. With experience, surgical times are decreasing and fusion and curve correction rates are improving. With further evolution, patients should realize shortened hospitalization, decreased rehabilitation times, and decreased levels of postoperative pain. This is a technically demanding procedure and requires demonstrated skills in endoscopic discectomy and fusion.

Parental smoking and childhood cancer: results from the United Kingdom Childhood Cancer Study

There are strong a priori reasons for considering parental smoking behaviour as a risk factor for childhood cancer but case - control studies have found relative risks of mostly only just above one. To investigate this further, self-reported smoking habits in parents of 3838 children with cancer and 7629 control children included in the United Kingdom Childhood Cancer Study (UKCCS) were analysed. Separate analyses were performed for four major groups (leukaemia, lymphoma, central nervous system tumours and other solid tumours) and more detailed diagnostic subgroups by logistic regression. In the four major groups, after adjustment for parental age and deprivation there were nonsignificant trends of increasing risk with number of cigarettes smoked for paternal preconception smoking and nonsignificant trends of decreasing risk for maternal preconception smoking (all P-values for trend >0.05). Among the diagnostic subgroups, a statistically significant increased risk of developing hepatoblastoma was found in children whose mothers smoked preconceptionally (OR=2.68, P=0.02) and strongest (relative to neither parent smoking) for both parents smoking (OR=4.74, P=0.003). This could be a chance result arising from multiple subgroup analysis. Statistically significant negative trends were found for maternal smoking during pregnancy for all diagnoses together (P<0.001) and for most individual groups, but there was evidence of under-reporting of smoking by case mothers. In conclusion, the UKCCS does not provide significant evidence that parental smoking is a risk factor for any of the major groups of childhood cancers.