Paul B. Nelson

Large and giant paraclinoid aneurysms: Surgical techniques, complications, and results

Twenty-five patients with giant (greater than 25 mm in diameter) and 9 patients with large (15 to 25 mm in diameter) aneurysms of the internal carotid artery in the ophthalmic or paraophthalmic region are reviewed. In 23 of these patients the aneurysm was clipped directly. There was 1 death in this group, and none of the survivors had disabling neurological complications outside the visual system. The other 11 patients were treated by a trapping procedure or by either common carotid ligation or internal carotid ligation in the neck. Of the 5 patients treated by internal carotid ligation preceded by an extracranial to intracranial bypass graft, 3 developed embolic complications, which in 1 patient resulted in death. One of the 4 patients treated by ligation of the common carotid artery died 1 year later from a recurrent subarachnoid hemorrhage. Of the total group, 18 patients had visual loss preoperatively as a result of aneurysmal compression; in 10 the vision was improved by operation, in 3 it was made worse, and in 2 it was unchanged. In another patient the vision continued to deteriorate slowly after common carotid occlusion, and the other 2 patients died postoperatively before vision could be assessed. The complications in the patients are described and analyzed in detail. Maneuvers found to be of value in the direct approach to these lesions are described. Of these, exposure of the internal carotid artery in the neck for temporary occlusion during clipping and thorough drilling of the anterior clinoid process and unroofing of the optic canal were particularly helpful. The literature on indirect methods of treatment by carotid occlusion with and without bypass graft is reviewed with special reference to the complications and effectiveness of each alternative. Based on this review of the literature and our experience, a treatment scheme is suggested for these aneurysms depending on their mode of presentation.

Radiotherapy of nonfunctional adenomas of the pituitary gland. Results with long-term follow-up

A total of 112 patients with the diagnosis of nonfunctional pituitary adenoma received radiation therapy at the University of Pittsburgh between 1964 and 1987. Postoperative radiation therapy was administered in 87 patients. Actuarial progression‐free survival (tumor control) at 5, 10, 15, and 20 years was 97%, 89%, 87%, and 76%, respectively. Radiation prescribed to the 95% isodose ranged from 35.72 Gy to 62.32 Gy. Multivariate analysis showed decreased tumor control to be significantly associated with increasing field size (P =.036). No improvement in tumor control could be detected with increasing total radiation dose or nominal standard dose (NSD). One patient developed optic neuropathy and another developed a glioblastoma after doses in both patients of 4750 cGy in 25 fractions. External beam radiotherapy for nonfunctional pituitary adenomas was found to be effective and safe when doses less than 4750 cGy in 25 fractions were used.

Incidence of cerebral infarction after radiotherapy for pituitary adenoma

The incidence of cerebral infarction was studied in 156 patients irradiated for treatment of pituitary adenomas. Seven patients experienced strokes at intervals of 3.2 to 14.6 years after irradiation. The observed incidence was not significantly greater than the expected value of 3.5 strokes (P = 0.078). Six strokes occurred in patients receiving equivalent doses (ED) of 1070 ret or more (observed to expected ratio 3.87, significantly elevated; P < 0.001). Univariate log‐rank analysis showed that the risk of stroke was significantly higher (P = 0.010) in patients receiving an ED of 1070 ret or more (4180 cGy/22 fractions) than those receiving lower doses. Multivariate analysis, however, demonstrated that the increased risk of stroke was associated only with increasing age (P < 0.0001), not ED (P = 0.148). Due to these inconsistent statistical results, no definitive conclusions could be reached about the relationship between radiation dose to the pituitary and subsequent cerebral infarction.

Metastatic tumor of the pituitary gland.

Although metastatic tumors of the pituitary gland and the sellar region are not common, they may radiographically mimic a pituitary tumor. Because the metastasis frequently involves the posterior lobe and because lateral extension to the cavernous sinus is common, patients may present with ptosis, diplopia, or diabetes insipidus. Decrease in anterior pituitary function is less common. Metastatic tumors contain abundant vascular networks, as evidenced by frequent blush on cerebral angiography and increased bleeding at operation. We report the case of a 57-year-old woman who presented with rapid onset of bilateral ptosis and ophthalmoplegia and was found to have a metastatic carcinoma within the pituitary gland.

Abscess formation within pituitary tumors.

Three consecutive cases where abscesses were found within pituitary tumors are presented. In all cases, the diagnosis was made preoperatively and the patients were begun on stress doses of hydrocortisone and antibiotics before surgical drainage of the abscess. All patients recovered with minimal neurological deficits. Review of the literature reveals that the diagnosis is seldom made preoperatively or before autopsy and is associated with high mortality and morbidity. Early suspicion of a pituitary abscess leading to early treatment with antibiotics and operative drainage seem to be important factors in decreasing this high mortality and morbidity.

Transient Hyponatremia after Damage to the Neurohypophyseal Tracts

Section of the neurohypophyseal stalk classically produces a triphasic response: diabetes insipidus (1st phase), hyponatremia or normonatremia (2nd phase), and diabetes insipidus (3rd phase). Transient hyponatremia without diabetes insipidus has been reported after transsphenoidal pituitary surgery. We report two additional cases of transient hyponatremia which occurred 6-8 days after pituitary surgery. We hypothesize that this outcome may be due to partial section or damage of the hypothalamiconeurohypophyseal tracts. The remaining intact vasopressin neurons function normally to protect against the diabetes insipidus of the first and third phase, but leak of vasopressin from the damaged tracts and posterior pituitary is sufficient to cause what can be described as an isolated second phase. To study this hypothesis in rats, partial damage to the hypothalamicneurohypophyseal tracts was produced by radiofrequency lesions. The lesions did not affect anterior pituitary function. A variety of responses in posterior pituitary function occurred, including classic triphasic response in 2 rats and transient hyponatremia in 20 of 35 lesioned animals. The mean sodium nadir was 128.7 +/- 1.5 mEq/l in comparison to the sham-operated value of 140.0 +/- 0.4 mEq/l. Of the 20 rats exhibiting transient hyponatremia, 12 went on to develop diabetes insipidus, and 8 recovered. In the recovered group, the transient hyponatremia occurred 1-3 days after lesioning and returned to normal by day 7 which corresponds to the timing of the second phase of the triphasic response in rats. Hyponatremia was accompanied by vasopressin levels inappropriate for the plasma sodium level, inappropriately concentrated urine, water retention, and natriuresis.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain abscess complicating the use of a halo orthosis.

We report a case of brain abscess complicating the use of a halo orthosis in the treatment of a cervical spine injury suffered during wrestling. Four previous brain abscesses complicating the use of halo orthoses have been reported. All cases of abscess have been associated with overlying infection at the site of pin insertion. Our case and at least one of those previously reported may have been related to tightening of the halo pins after placement. Serious spine injuries occur rarely in wrestlers and are associated with the use of illegal holds and maneuvers in which one athlete is thrown to the mat. The pathophysiology and radiographic appearance of a unilateral facet dislocation are reviewed.

Invasive pituitary adenoma with abscess formation: case report.

A case is presented and 10 cases are reviewed in which abscess formation developed in an intrasellar tumor. The diagnosis was made preoperatively or before autopsy in only 1 patient. The mortality rate was greater than 50%. The most common presentation was headache, fever, and visual disturbances with an abnormal sella and sterile cerebrospinal fluid (CSF). Nonconstant findings included meningeal signs and leukocytosis of the CSF. Trans-sphenoidal removal of the tumor and drainage of the abscess with appropriate antibiotic therapy is recommended. (Neurosurgery, 5: 718--722, 1979).

Monitoring of cortical somatosensory evoked potentials to determine the safety of sacrificing the anterior cerebral artery

Cortical somatosensory evoked potentials (SSEPs) reflect the functional integrity of somatosensory pathways from the site of stimulation to the primary somatosensory cortex. We used intraoperative monitoring of cortical SSEPs to determine whether the right anterior cerebral artery (RACA), the major feeding vessel of a large arteriovenous malformation (AVM), could be sacrificed without compromising sensorimotor function in the left lower extremity. The SSEPs recorded after test occlusion of the RACA showed preservation of the initial cortical positivity, and the RACA was divided. The AVM was excised completely, and the patient suffered no neurological deficit.

Endocrine Function in Patients with Large Pituitary Tumors Treated with Operative Decompression and Radiation Therapy

Large pituitary tumors are still a common problem. Thirty consecutive patients underwent operative decompression and radiation therapy for large sellar and suprasellar tumors. They were studied prospectively in terms of their endocrine outcome. Ten of the patients had panhypopituitarism both before and after treatment. The other 20 patients had partial hormonal deficits prior to treatment. Ten (50%) of the 20 patients who had partial preoperative deficits went on to develop delayed onset of worsening in their endocrine function; 9 of the 10 developed panhypopituitarism, and 1 patient developed decreased thyroid function. The mean time from surgery until the onset of delayed worsening in endocrine function was 26.1 months. The mean age of those patients who developed delayed onset of worsening in pituitary function was significantly higher than that of those who did not develop further hormonal loss (40.5 +/- 3.1 years versus 52.0 +/- 4.1 years, P less than 0.05). None of the 10 patients with delayed onset of worsening in pituitary function had anatomical evidence by computed tomographic scan of tumor recurrence. Delayed onset radiation effect is the most likely cause of the late onset of worsening in endocrine function.