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Michael C. Dewan, Ronnie E. Baticulon, Abbas Rattani, James M. Johnston Jr., Benjamin C. Warf and William Harkness

OBJECTIVE

The presence and capability of existing pediatric neurosurgical care worldwide is unknown. The objective of this study was to solicit the expertise of specialists to quantify the geographic representation of pediatric neurosurgeons, access to specialist care, and equipment and training needs globally.

METHODS

A mixed-question survey was sent to surgeon members of several international neurosurgical and general pediatric surgical societies via a web-based platform. Respondents answered questions on 5 categories: surgeon demographics and training, hospital and practice details, surgical workforce and access to neurosurgical care, training and equipment needs, and desire for international collaboration. Responses were anonymized and analyzed using Stata software.

RESULTS

A total of 459 surgeons from 76 countries responded. Pediatric neurosurgeons in high-income and upper-middle-income countries underwent formal pediatric training at a greater rate than surgeons in low- and lower-middle-income countries (89.5% vs 54.4%). There are an estimated 2297 pediatric neurosurgeons in practice globally, with 85.6% operating in high-income and upper-middle-income countries. In low- and lower-middle-income countries, roughly 330 pediatric neurosurgeons care for a total child population of 1.2 billion. In low-income countries in Africa, the density of pediatric neurosurgeons is roughly 1 per 30 million children. A higher proportion of patients in low- and lower-middle-income countries must travel > 2 hours to seek emergency neurosurgical care, relative to high-income countries (75.6% vs 33.6%, p < 0.001). Vast basic and essential training and equipment needs exist, particularly low- and lower-middle-income countries within Africa, South America, the Eastern Mediterranean, and South-East Asia. Eighty-nine percent of respondents demonstrated an interest in international collaboration for the purposes of pediatric neurosurgical capacity building.

CONCLUSIONS

Wide disparity in the access to pediatric neurosurgical care exists globally. In low- and lower-middle-income countries, wherein there exists the greatest burden of pediatric neurosurgical disease, there is a grossly insufficient presence of capable providers and equipped facilities. Neurosurgeons across income groups and geographic regions share a desire for collaboration and partnership.

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Kanna K. Gnanalingham, Jesus Lafuente, Dominic Thompson, William Harkness and Richard Hayward

Object. Traditionally, access to the posterior fossa involved a suboccipital craniectomy. More recently, posterior fossa craniotomies have been described, although the long-term benefits of this procedure are not clear. The authors compared the postoperative complications of craniectomies and craniotomies in children with posterior fossa tumors.

Methods. From a total of 110 children undergoing surgery for posterior fossa tumors, 56 underwent craniectomy and 54 had a craniotomy. The mean duration of the hospital stay was longer in the craniectomy group (17.5 compared with 14 days). At operation, similar numbers of patients in both groups had total macroscopic clearance of the tumor, complete dural closure, and duraplasty.

Postoperatively, more patients in the craniectomy group were noted to have cerebrospinal fluid (CSF) leakage (27 compared with 4%; p < 0.01) and pseudomeningoceles (23 compared with 9%; p < 0.05). There was no significant difference between the two groups in the numbers of patients with CSF infections, wound infections, or hydrocephalus requiring permanent CSF drainage. Patients with CSF leaks had a longer duration of hospital stay (20.7 compared with 14.9 days; p < 0.01), and were more likely to have CSF infections (35 compared with 12%; p < 0.01) and wound infections (24 compared with 1%; p < 0.01) than patients without CSF leaks. Postoperatively, wound exploration and reclosures for CSF leakage were more likely in the craniectomy group (11 compared with 0%; p < 0.01). Multivariate analysis revealed that the only predictor of CSF leakage postoperatively was the type of surgery (that is, craniotomy compared with craniectomy; odds ratio 10.8; p = 0.03).

Conclusions. Craniectomy was associated with postoperative CSF leaks, pseudomeningocele, increased wound reclosures, and thus prolonged hospital stays. In turn, CSF leakage was associated with infections of the CSF and wound. The authors propose mechanisms that may explain why CSF leakage is less likely if the bone flap is replaced.

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Medulloblastoma: is the 5-year survival rate improving?

A review of 80 cases from a single institution

Karoly M. David, Adrian T. H. Casey, Richard D. Hayward, William F. J. Harkness, Kim Phipps and Angie M. Wade

✓ A series of 80 cases of medulloblastomas in children undergoing operation and postoperatively followed between 1980 and 1990 at Great Ormond Street Hospital for Children (GOSH) has been reviewed and compared to an earlier series reported from the same institution by McIntosh. The overall 5-year survival rate for the present series was 50%, although three patients died after surviving 5 years. The operative mortality rate was 5%. Survival analysis revealed that the presence or absence of spinal metastases and the necessity for some form of cerebrospinal fluid diversion within 30 days of the operation independently significantly affected survival in this series. Those patients with no spinal metastasis and total tumor removal had a 5-year survival rate of 73%, making this the most favorable subgroup in the series. Patient age and gender, duration of symptoms, Chang T stages, tumor volume, extent of resection, and postoperative chemotherapy were not significant variables.

Although these results are better than those reported in the earlier GOSH series, they are not significantly different from the results of the second 5-year cohort of patients described in that article. Radiotherapy remains the greatest advance in treatment, although it is hoped that further improvement will result from the various chemotherapy protocols now being studied and from increasing knowledge of the biological behavior of these tumors.

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Dominic N. P. Thompson, Richard D. Hayward, William J. Harkness, Robert M. Bingham and Barry M. Jones

✓ The authors describe the clinical, radiological, and postmortem findings of a case of cloverleaf skull syndrome. The presence of hindbrain herniation, abnormal cervical segmentation, and atlantoaxial subluxation illustrate the anatomical complexity of the skull base and the craniocervical junction that may coexist in this condition. Unavoidable division of occipital emissary veins during elevation of the skin flap at the time of vault remodeling surgery led to an acute and, ultimately, fatal rise in intracranial pressure. Postmortem examination and review of magnetic resonance imaging revealed an anomalous pattern of venous drainage of the intracranial structures that appeared to have developed in response to venous obstruction, secondary to intraosseous venous sinuses and stenosis of the jugular foramina.

The relationship between venous hypertension, hindbrain herniation, and hydrocephalus in this situation is reviewed, and the implications for evaluation and management of this vexing disorder are discussed.

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Dominic N. P. Thompson, Adrian T. Casey, Richard D. Hayward and William F. Harkness

✓ A combined radiological and surgical technique that permits identification of appropriate recipient vessels and accurate placement of the atrial catheter in ventriculoatrial shunts is described. The procedure uses readily available radiological skills and reduces operation time and morbidity related to malpositioning of the distal catheter.

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Neil L. Dorward, Olaf Alberti, Binti Velani, Frans A. Gerritsen, William F. J. Harkness, Neil D. Kitchen and David G. T. Thomas

Object. This prospective study was conducted to quantify brain shifts during open cranial surgery, to determine correlations between these shifts and image characteristics, and to assess the impact of postimaging brain distortion on neuronavigation.

Methods. During 48 operations, movements of the cortex on opening, the deep tumor margin, and the cortex at completion were measured relative to the preoperative image position with the aid of an image-guidance system. Bone surface offset was used to assess system accuracy and correct for registration errors. Preoperative images were examined for the presence of edema and to determine tumor volume, midline shift, and depth of the lesion below the skin surface. Results were analyzed for all cases together and separately for four tumor groups: 13 meningiomas, 18 gliomas, 11 nonglial intraaxial lesions, and six skull base lesions.

For all 48 cases the mean shift of the cortex after dural opening was 4.6 mm, shift of the deep tumor margin was 5.1 mm, and shift of the cortex at completion was 6.7 mm. Each tumor group displayed unique patterns of shift, with significantly greater shift at depth in meningiomas than gliomas (p = 0.007) and significantly less shift in skull base cases than other groups (p = 0.003). Whereas the preoperative image characteristics correlating with shift of the cortex on opening were the presence of edema and depth of the tumor below skin surface, predictors of shift at depth were the presence of edema, the lesion volume, midline shift, and magnitude of shift of the cortex on opening.

Conclusions. This study quantified intraoperative brain distortion, determined the different behavior of tumors in four pathological groups, and identified preoperative predictors of shift with which the reliability of neuronavigation may be estimated.

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Neil L. Dorward, Olaf Alberti, Binti Velani, Frans A. Gerritsen, William F. J. Harkness, Neil D. Kitchen and David G. T. Thomas

This prospective study was conducted to quantify brain shifts during open cranial surgery, to determine correlations between these shifts and image characteristics, and to assess the impact of postimaging brain distortion on neuronavigation.

During 48 operations, movements of the cortex on opening, the deep tumor margin, and the cortex at completion were measured relative to the preoperative image position with the aid of an image-guidance system. Bone surface offset was used to assess system accuracy and correct for registration errors. Preoperative images were examined for the presence of edema and to determine tumor volume, midline shift, and depth of the lesion below the skin surface. Results were analyzed for all cases together and separately for four tumor groups: 13 meningiomas, 18 gliomas, 11 nonglial intraaxial lesions, and six skull base lesions.

For all 48 cases the mean shift of the cortex after dural opening was 4.6 mm, shift of the deep tumor margin was 5.1 mm, and shift of the cortex at completion was 6.7 mm. Each tumor group displayed unique patterns of shift, with significantly greater shift at depth in meningiomas than gliomas (p = 0.007) and significantly less shift in skull base cases than other groups (p < 0.003). Whereas the preoperative image characteristics correlating with shift of the cortex on opening were the presence of edema and depth of the tumor below skin surface, predictors of shift at depth were the presence of edema, the lesion volume, midline shift, and magnitude of shift of the cortex on opening.

This study quantified intraoperative brain distortion, determined the different behavior of tumors in four pathological groups, and identified preoperative predictors of shift with which the reliability of neuronavigation may be estimated.

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Camilo E. Fadul, Andrew L. Kominsky, Louise P. Meyer, Linda S. Kingman, William B. Kinlaw, C. Harker Rhodes, Clifford J. Eskey and Nathan E. Simmons

✓Pituitary carcinoma is a rare tumor characterized by poor responsiveness to therapy, leading to early death. Reported responses to standard chemotherapy have only been anecdotal, with no single agent or combination demonstrating consistent efficacy in the treatment of patients with this disease. The authors report rare examples of a persistent response to cytotoxic chemotherapy in two patients with pituitary carcinoma.

One patient was a 38-year-old man with visual field loss caused by a luteinizing hormone–secreting pituitary carcinoma that had recurred despite multiple surgeries and radiation therapy. Intradural metastases to the spine that had failed to respond to radiation therapy were pathologically confirmed. The second patient was a 26-year-old man with hyperprolactinemia from a prolactin-secreting pituitary tumor. Spine magnetic resonance images obtained to search for causes of neck pain showed a vertebral tumor, which was later confirmed through pathological analysis to be a metastatic pituitary carcinoma. His disease progressed despite radiation therapy, high-dose bromocriptine, and chemotherapy.

Both patients were treated monthly with temozolomide, which was administered orally on the first 5 days of a 28-day cycle. The patient in the first case underwent all 12 treatment cycles without serious side effects, and his visual field deficits improved. The patient in the second case had undergone only 10 cycles when the drug was stopped because of his severe fatigue. Nonetheless, his pain disappeared and his serum prolactin concentration decreased. Both patients continue to have partial responses and have been employed full-time for more than 1 year after discontinuing temozolomide therapy. These two examples demonstrate that temozolomide may be effective in treating pituitary carcinomas and thus should be considered in the treatment algorithm for these difficult cases.