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Donald A. Ross

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Donald A. Ross and Charles B. Wilson

✓ Of 214 patients with acromegaly who underwent transsphenoidal microsurgical resection of a pituitary adenoma, 54% had growth hormone (GH) levels below 5 ng/ml and 74% had levels less than 10 ng/ml immediately after surgery. Among the 174 patients who could be contacted for long-term follow-up review (average duration 76 months), most recent GH determinations were available for 165. Of these 165 patients, 131 (79.4%) have a GH level less than 5 ng/ml and 153 (92.7%) have a level below 10 ng/ml; these represent 75.3% and 87.9%, respectively, of the total 174 patients reviewed. Fifty-two patients received postoperative radiation therapy. Nine patients underwent reoperation. There were five cases of tumor recurrence following an apparent surgical cure (4.3%), nine new instances of anterior pituitary hypofunction (5%), and five failures of multimodality therapy (2.3%). There were no perioperative deaths, five cases of cerebrospinal fluid leak requiring surgical repair (2.2%), and four cases of postoperative meningitis (1.8%). Permanent diabetes insipidus did not occur. Two of 52 patients who were irradiated postoperatively had severe complications; 23 (54.8%) of 42 patients who were available for follow-up evaluation had developed panhypopituitarism; and eight (19%) of 42 had normal pituitary function an average of 44 months postirradiation.

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Gary P. Colón, Donald A. Ross, and Julian T. Hoff

✓ A hyperossified meningioma with significant calvarial thickening is fairly common. Craniectomy of the involved region followed by cranioplasty is usually required to resect the bone overgrowth. However, in some cases, the hyperossified calvaria is too thick to allow safe penetration with a craniotome or trephine. In this report, the authors present a technique for preserving the outer calvaria while still resecting the majority of the underlying tumor mass. The key is to perform a craniotomy in a region adjacent to the hyperossified bone and to remove the tumorous, ossified inner table through this “window” by means of a high-speed drill. A second craniotomy can then be performed over the undermined area; this maneuver can be advanced and repeated until the tumor is resected. Frameless stereotactic guidance and microplates are useful in performing this procedure.

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Donald A. Ross, Walter L. Olsen, Amy M. Ross, Brian T. Andrews, and Lawrence H. Pitts

✓ Recently, Ropper reported that horizontal brain shift caused by acute unilateral mass lesions correlated closely with consciousness, and suggested that recovery of consciousness was unlikely to occur after surgical evacuation if the shift was insufficient to explain the observed diminution of consciousness. The authors have sought to confirm the correlation of pineal shift with level of consciousness and to assess the prognostic value of brain shift measurements in a prospective study. Forty-six patients (19 with subdural hematoma, 14 with intracerebral hematoma, and 13 with epidural hematoma) were accrued to the study group consecutively. A correlation was found between a decrease in the level of consciousness and a significant increase in the mean lateral brain displacement at the pineal gland (from 3.8 to 7.0 mm) and septum (5.4 to 12.2 mm). When outcome was examined in patients who were stuporous or comatose on admission, a significant increase in septal shift was found among patients with a poor outcome, but there was no significant relationship between outcome and degree of pineal or aqueductal shift. A poor outcome was more likely with effacement of both perimesencephalic cisterns or the ipsilateral cistern, but not the contralateral cistern, although this difference did not reach statistical significance. These results do not substantiate the value of brain shift as an independent prognostic factor after evacuation of an acute unilateral mass lesion. The decision to operate and the determination of prognosis should be based rather on established criteria such as the clinical examination, age of the patient, and the mechanism of injury.

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Griffith R. Harsh IV, George W. Sypert, Philip R. Weinstein, Donald A. Ross, and Charles B. Wilson

✓ Ossification of the posterior longitudinal ligament (OPLL) is a well-documented cause of cervical spine stenosis and myelopathy among Japanese patients. Reports of OPLL in North Americans are rare. Choices of diagnostic method and treatment for this entity remain controversial. The authors report the results of management of 20 patients in the United States with symptomatic OPLL of the cervical spine. These represented 10% to 20% of patients operated on over the last 3 years for myelopathy secondary to structural spinal compression. Most of these OPLL patients were Caucasian (60%), male (male:female 4:1), and middle-aged (median age 47.5 years). Six had previously undergone laminectomy or discectomy. Cervical roentgenograms and standard myelography occasionally suggested the diagnosis. Axial computerized tomography (CT) metrizamide myelography with small interslice intervals proved invaluable for diagnosis and operative planning. Magnetic resonance imaging was not necessary for diagnosis. Retrovertebral calcification extended over one to five bodies (mean 2.75). The mass ranged in size from 5 to 16 mm in anteroposterior diameter and reduced the residual canal diameter to a mean (± standard deviation) caliber of 9.42 ± 2.41 mm (mean narrowing ratio 0.44 ± 0.12).

Anterior cervical decompression by medial corpectomy and discectomy with fusion uniformly reduced preoperative myelopathy. Complications were limited to transient neurological deterioration in two patients, recurrent laryngeal nerve palsy in one, and halo device pin site infections in two. At a mean postoperative interval of 15 months, improvement was seen in each category of deficit: extremity weakness, hypesthesia, hypertonia, and urinary dysfunction. All fusions produced solid unions.

It is concluded that OPLL of the cervical spine is an unexpectedly prevalent cause of myelopathy among patients treated in the United States. Thin-section axial CT metrizamide myelography with small interslice intervals is essential for the investigation of patients who may have OPLL. Anterior decompression and stabilization by medial corpectomy, discectomy, removal of the calcified mass, and fusion is a safe and effective method of treatment.

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Gary P. Colón, Douglas J. Quint, Lawrence D. Dickinson, James A. Brunberg, Kenneth A. Jamerson, Julian T. Hoff, and Donald A. Ross

Object. The authors designed a blinded prospective study comparing patients with essential hypertension to patients without hypertension in which magnetic resonance (MR) imaging was used to evaluate the role of lateral medullary compression by adjacent vascular structures as a cause of neurogenic hypertension.

Methods. Patients with documented essential hypertension were recruited to undergo thin-slice axial brainstem MR imaging evaluation. Nonhypertensive (control) patients scheduled to undergo MR imaging for other reasons also underwent thin-slice MR imaging to form a basis for comparison. Magnetic resonance images obtained in patients from the hypertensive (30 patients) and the control (45 patients) groups were then compared by four independent reviewers (two neuroradiologists and two neurosurgeons) who were blinded to the patients' diagnosis and hypertensive status. Images were reviewed with regard to left versus right vertebral artery (VA) dominance, compression of the medulla on the left and/or right side, and brainstem rotation. Medullary compression was graded as either vessel contact without associated brainstem deformity or vessel contact with associated brainstem deformity.

Conclusions. There was a tendency toward left VA dominance in the hypertensive group compared with the control group, although a significant difference was shown by only one of the four reviewers. There were no differences in brainstem compression or rotation between the hypertensive and nonhypertensive groups.

These results are contrary to those of recently published studies in which MR imaging and/or MR angiography revealed lateral brainstem vascular compression in hypertensive patients but not in nonhypertensive (control) patients. Reasons for this discrepancy are discussed. On the basis of their own experience and that of others, the authors believe that neurogenic hypertension does exist. However, thin-slice MR imaging may not be a reliable method for detecting neurovascularly induced essential hypertension and the prevalence of neurovascular compression as the source of hypertension may be overestimated when using current imaging techniques.