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Editorial

Transnasal endoscopic surgery for craniopharyngiomas

Edward H. Oldfield

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Editorial

Unresolved issues: radiosurgery versus radiation therapy; medical suppression of growth hormone production during radiosurgery; and endoscopic surgery versus microscopic surgery

Edward H. Oldfield

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Edward H. Oldfield

From the earliest observations of spinal vascular malformations, successful management has been challenging. Initially the challenges were diagnosing, understanding, and treating these lesions. They were originally considered all to be the same, or at least to be a single general type, of disease. With the introduction of selective spinal arteriography in the 1960s and more recently with the introduction and widespread use of MR imaging, the initial challenge of diagnosing spinal vascular malformations was overcome, and significant progress has been made in understanding their anatomy as well as the pathophysiology that underlies the myelopathy commonly associated with them. The anatomical features defined by selective arteriography and the observations permitted with the operating microscope ultimately led to distinctions between the major categories of the vascular lesions affecting the spinal cord; these distinctions were based on the lesions' anatomy, epidemiology, and the mechanism of spinal cord injury.

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Houssein A. Darwish and Edward H. Oldfield

This report describes the circumstances of a patient with a cauda equina syndrome due to the development of a lumbar subdural CSF collection with ventral displacement of the cauda equina shortly following posterior fossa decompression for Chiari malformation Type I (CM-I). This unusual, but clinically significant, complication was successfully treated with percutaneous drainage of the extraarachnoid CSF collection. Although there are a few cases of intracranial subdural hygroma developing after surgery for CM-I, often attributed to a pinhole opening in the arachnoid, as far as the authors can determine, a spinal subdural hygroma associated with surgery for CM-I has not been recognized.

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Marsha J. Merrill and Edward H. Oldfield

✓ Overexpression of vascular endothelial growth factor (VEGF) is associated with several central nervous system (CNS) diseases and abnormalities, and is often postulated as a causative factor and promising therapeutic target in these settings. The authors' goal was to reassess the contribution of VEGF to the biology and pathology of the CNS.

The authors review the literature relating to the following aspects of VEGF: 1) the biology of VEGF in normal brain; 2) the involvement of VEGF in CNS disorders other than tumors (traumatic and ischemic injuries, arteriovenous malformations, inflammation); and 3) the role of VEGF in brain tumor biology (gliomas and the associated vasogenic edema, and hemangioblastomas).

The authors conclude the following: first, that VEGF overexpression contributes to the phenotype associated with many CNS disorders, but VEGF is a reactive rather than a causative factor in many cases; and second, that use of VEGF as a therapeutic agent or target is complicated by the effects of VEGF not only on the cerebral vasculature, but also on astrocytes, neurons, and inflammatory cells. In many cases, therapeutic interventions targeting the VEGF/VEGF receptor axis are likely to be ineffective or even detrimental. Clinical manipulation of VEGF levels in the CNS must be approached with caution.

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Gautam U. Mehta and Edward H. Oldfield

Object

Cerebrospinal fluid leakage is a major complication of transsphenoidal surgery. An intraoperative CSF leak, which occurs in up to 50% of pituitary tumor cases, is the only modifiable risk factor for postoperative leaks. Although several techniques have been described for surgical repair when an intraoperative leak is noted, none has been proposed to prevent an intraoperative CSF leak. The authors postulated that intraoperative CSF drainage would diminish tension on the arachnoid, decrease the rate of intraoperative CSF leakage during surgery for larger tumors, and reduce the need for surgical repair of CSF leaks.

Methods

The results of 114 transsphenoidal operations for pituitary macroadenoma performed without intraoperative CSF drainage were compared with the findings from 44 cases in which a lumbar subarachnoid catheter was placed before surgery to drain CSF at the time of dural exposure and tumor removal.

Results

Cerebrospinal fluid drainage reduced the rate of intraoperative CSF leakage from 41% to 5% (p < 0.001). This reduction occurred in macroadenomas with (from 57% to 5%, p < 0.001) and those without suprasellar extension (from 29% to 0%, p = 0.31). The rate of postoperative CSF leakage was similar (5% vs 5%), despite the fact that intraoperative CSF drainage reduced the need for operative repair (from 32% to 5%, p < 0.001). There were no significant catheter-related complications.

Conclusions

Cerebrospinal fluid drainage during transsphenoidal surgery for macroadenomas reduces the rate of intraoperative CSF leaks. This preventative measure obviated the need for surgical repair of intraoperative CSF leaks using autologous fat graft placement, other operative techniques, postoperative lumbar drainage, and/or reoperation in most patients and is associated with minimal risks.

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Ian E. McCutcheon and Edward H. Oldfield

✓ The authors report a nulliparous patient presenting with infertility and hyperprolactinemia. She underwent transsphenoidal surgery after radiological investigation disclosed an enlarged pituitary gland which did not respond to bromocriptine therapy. The removed tissue had histological features consistent with adenohypophysitis including a diffuse lymphocytic infiltrate. The lymphocyte subsets present in the infiltrate were characterized by immunohistochemical methods to establish the contribution of different elements of the cellular immune response.

Lymphocytes bearing CD4 antigen (helper-inducer cells) were most prominent and appeared to bear the majority of the interleukin-2 receptor (expressed during lymphocytic activation) present in the pituitary gland. A few B lymphocytes were also observed. The location of the major histocompatibility antigen (classes I and II) and interleukin-2 receptor correlated with the lymphocytes and macrophages rather than with the stromal or parenchymal elements of the pituitary.

Lymphocytic adenohypophysitis is an unusual cause of pituitary enlargement which can mimic a pituitary tumor, and is sometimes associated with hyperprolactinemia. In women of child-bearing age, it almost always occurs during pregnancy or the postpartum stage. The autoimmune disorder reported here has not previously been associated with infertility nor has the lymphocytic infiltrate of the pituitary previously been analyzed in detail by modern immunological methods.

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Edward H. Oldfield

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John K. Ratliff and Edward H. Oldfield

Object. Clinically evident multiple pituitary adenomas rarely occur. The authors assess the incidence and clinical relevance of multiple adenomas in Cushing's disease.

Methods. A prospective clinical database of 660 pituitary surgeries was analyzed to assess the incidence of multiple pituitary adenomas in Cushing's disease. Relevant radiographic scans, medical records, and histopathological reports were reviewed.

Thirteen patients with at least two separate histopathologically confirmed pituitary adenomas were identified. Prolactinomas (nine patients) were the most common incidental tumors. Other incidental tumors included secretors of growth hormone ([GH], one patient) and GH and prolactin (two patients), and a null-cell tumor (one patient). In two patients, early repeated surgery was performed because the initial operation failed to correct hypercortisolism, in one instance because the tumor excised at the initial surgery was a prolactinoma, not an adrenocorticotropic hormone—secreting tumor. One patient had three distinct tumors.

Conclusions. Multiple pituitary adenomas are rare, but may complicate management of patients with pituitary disease.