Biomedical subjects
Publications and source records attributed to J Ransohoff.
Eighteen patients over 60 years old with a histologically proven diagnosis of glioblastoma multiforme were treated by a short radiotherapy course (3000 cGy midline dose by two opposed portals to the whole brain). Results in terms of survival and function appeared to be as good as with the standard course of six to seven weeks as reported in the literature.
We report a case of malignant melanoma, metastatic to the brain, in which disease was not detected by magnetic resonance imaging but was detected by contrast enhanced computed tomography. At least in some instances, magnetic resonance imaging fails to detect disease that is apparent by computed tomography.
We studied the effects of intra-arterial chemotherapy on the visual system of 29 consecutive patients with gliomas. As expected, infra-ophthalmic carotid infusion of cisplatin or carmustine (BCNU) was associated with clinically apparent anterior visual pathway lesions. Electroretinography revealed retinal dysfunction in patients without clinical abnormalities. Supra-ophthalmic carotid infusion of cisplatin or BCNU caused no retinal or optic nerve lesions. Electroretinography was abnormal in only one of these patients. Our results indicated that BCNU and cisplatin cause ischemic damage and are toxic to both retinal and neural tissue in patients with gliomas.
Vocal cord paralysis may follow intracranial operation if the vagus nerve is damaged intraoperatively. If the resulting laryngeal incompetence is severe, hoarseness, dysphagia, and aspiration may develop. This is often followed by a pneumonitis requiring chronic gastric tube feeding. Teflon vocal cord injection has been shown to restore the sphincteric action of the larynx and enable patients to phonate and swallow properly again. Nine patients underwent this procedure for chronic aspiration and hoarseness. All had vagus injury attributable to antecedent intracranial operation, and all experienced relief of their symptoms with only minor complications. Teflon vocal cord injection is advocated as a safe, effective means of managing patients with aspiration and dysphagia secondary to vagus nerve injury.
In a series of four patients with intracranial meningiomas, three-dimensional computed tomographic (CT) reconstructions were a useful diagnostic and surgical adjunct. Three-dimensional images are created from standard CT data by a boundary-detecting computer software program. Three-dimensional images of tumor invading or adjacent to the bony calvarium are projected about the x, y, and z axes. Axial and sagittal sections delineate the lesions. The images created allow a surgical view of the meningiomas in three-dimensional space and demonstrate the relationship of these masses to the skull. The use of three-dimensional reconstructions in craniofacial surgery and in neurosurgery is reviewed.
For reinnervation of facial paralysis, the XII-VII nerve anastomosis provides tone and mass contraction but rarely allows selective muscle control. The efficacy of EMG rehabilitation was evaluated in 30 patients who had no coordinated control of facial muscles. EMG signals from bilateral homologous facial muscle sites were converted into computer-compatible waveform traces and displayed on a video monitor. This facilitated modification of neuromuscular responses using behavioral shaping techniques. A six-point Facial Nerve Grading Scale was introduced for hypoglossal-facial nerve anastomosis to assess the results of EMG rehabilitation. Rehabilitation lasted from 3 to 18 months. Ten patients (33%) achieved the highest possible grading (II) with symmetry and synchrony of function and spontaneity of expression; 17 (57%) reached grade III, which allowed voluntary control of eye and mouth function; 3 (10%) showed minimal gains. It is suggested that neural plasticity allows therapeutic manipulation of central facilitory and inhibitory mechanisms, and possible unmasking of neural connections between the ipsilateral VII and XII nerve motor nuclei which leads to improved facial function.
Twenty patients with progressive visual loss caused by intracranial meningiomas involving the anterior visual pathway were treated with irradiation alone (n = 4) or with irradiation combined with tumor excision (n = 16). Improvement in visual performance occurred in 13 patients; 2 patients experienced temporary improvement; and 5 others maintained stable visual function for up to 9.5 years (mean follow-up, 4.0 years). Radiotherapy seemed to have no effect in 2 patients. One patient experienced temporary improvement, but eventually died from spread of tumor. Only one definite complication of radiotherapy occurred and was related to excessive radiation dose (greater than 7,000 cGy). Irradiation in the range of 5,000 to 5,500 cGy was effective either alone or in combination with surgical excision. Serial assessment of visual acuity and fields allowed us to demonstrate and quantify improvement in our patients following radiotherapy; in contrast, follow-up computed tomographic studies rarely demonstrated reduced tumor size.
The past two decades have evidenced a remarkable improvement in the capacity of otologic surgeons to treat cerebellopontine angle tumors. Advances in instrumentation because of technologic changes, coupled with better surgical training, have contributed to a highly successful rate of tumor removal. The capability to extirpate the tumor now permits the otologic surgeon to attempt simultaneous preservation of the facial and cochlear nerve functions. Just as middle ear surgery improved to the point in the 1950s that reconstruction as well as disease eradication became possible, so can surgeons now consider preservation of function of the inner ear. It is now technically feasible--in some instances--to attempt to preserve hearing in tumors of the eighth nerve. Several studies have provided evidence that the cochlear nerve can be anatomically and functionally preserved when neuromas involve either the inferior or superior vestibular nerves. However, other studies assert that grossly intact nerves may contain microscopic islands of tumor cells intermingled with nerve fibers. If viable tumor cells were allowed to remain behind, one would expect them to grow; this would result in loss of hearing function and tumor recurrence, as evidenced by computed tomography (CT) or magnetic resonance imaging (MRI). This article will discuss the issues of cochlear nerve preservation and tumor excision, and review our experience over the past decade.
Injury to the facial nerve is of concern in surgery of cerebellopontine angle tumors. The crossed acoustic reflex provides a way to monitor the ipsilateral facial nerve with the auditory stimuli delivered to the contralateral side. Using the method of optimum digital filtering, it is possible to monitor the resulting brain stem facial evoked response (BFER) in real time. This paper presents preliminary experiences in more than 18 such operations monitored using this method. This preliminary study demonstrates a trend for a high (88.8%) correlation between BFER and postoperative facial nerve function. Identical latencies from simultaneous BFER and facial nerve recordings along with findings after facial nerve transection suggest that some portion of the complex BFER waveform derives from facial nerve depolarization.
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Traumatic fistulas were successfully embolized using various transvascular approaches in 33 of 34 lesions. Complete superselective angiographic demonstration of the exact site of the shunt and possible collaterals was necessary to choose the appropriate embolization techniques. Improvement in the signs of orbital congestion was seen in all cases. Embolization, which directly occludes the fistula, precludes recurrences via collateralization and restores the normal arteriovenous gradient to the eye and optic nerve.
The signal-to-noise ratio of brainstem auditory evoked responses (BAER) can be greatly enhanced by use of optimal digital filtering before averaging. This permits accurate assessment of auditory nerve status every 5 to 10 seconds, making real-time intraoperative monitoring possible. The major advantages yielded by real-time monitoring--in our experience thus far--have been identification of potentially adverse functional consequences of apparently uneventful surgical maneuvers, reducing postoperative dysfunction, early indication of potential for improved clinical function, and potential identification and localization of neural tissue in the face of absent surgical landmarks. Examples of these advantages will be provided from case studies, and the possibility that real-time monitoring may improve ability to preserve hearing will be discussed.
We treated five patients with 11 supraophthalmic infusions of BCNU at 200 mg/m2 every 2 months. All three patients with residual tumors showed marked CT response after one infusion. Two patients with bilateral tumors had no response on the contralateral side. All four evaluable cases showed evidence of BCNU neurotoxicity. CT findings superficially resembled tumor recurrence, but white matter changes, nonspecific gyral enhancement, and delayed calcification were more indicative of neurotoxicity. There were no procedure-related complications. One autopsy suggested that direct parenchymal damage might be responsible for delayed neurotoxicity. Supraophthalmic BCNU infusion, at this dosage, is too toxic for cerebral tissue.
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We reviewed the records of 100 consecutive patients with histologically verified pituitary adenomas who underwent transsphenoidal decompression of the optic nerves and chiasm. The patients' ages ranged from 18 to 80 years, with a median of 52 years. Preoperatively, all patients had objective signs of visual acuity or field defects. Postoperatively, visual acuity was normal or improved in 79% of the eyes and the visual fields were normal or improved in 74%. The visual outcome (for both acuity and fields) was better in younger patients and those with a shorter duration of symptoms. Patients with lesser degrees of preoperative visual acuity compromise had better postoperative visual acuity outcome. However, the severity of preoperative visual field defects did not seem to predict postoperative field outcome, and even patients with severe preoperative field defects often had striking postoperative improvement. Patients who had undergone prior operation were less likely to have either visual acuity or visual field improvement after reoperation. Postoperative deterioration in visual acuity was noted in only 5 patients (6 eyes). Complications were few. There were 4 instances of cerebrospinal fluid rhinorrhea, but only 2 patients needed operative repair. There was no instance of permanent diabetes insipidus, although 17 patients developed transient diabetes insipidus. In most cases, visual improvement was sustained. The average duration of follow-up was 26 months. Three patients required a subsequent operation to correct visual loss in the immediate postoperative period, but only 1 patient has undergone late operation for recurrence of tumor. There was no operative mortality.
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