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Biomedical subjects

J M Tew

Publications and source records attributed to J M Tew.

At least 55 records · Page 3Linked to original sources
PubMed1995

Chiari I malformation: classification and management.

Considerable debate exists about which surgical options are best for the management of the Chiari I malformation. We present a classification system for the Chiari I malformation that improves the prediction of outcome and guides the selection of surgical treatment. Twenty-seven adult patients with Chiari I malformations were grouped on the basis of the presence of signs and symptoms of brain stem compression, syringomyelia, or both. To objectively assess changes in clinical status postoperatively, a scale was developed to quantify the signs and symptoms, which were statistically analyzed by the paired t test. Five patients were asymptomatic and underwent no treatment. Ten patients had symptoms of brain stem compression without associated syringomyelia and underwent brain stem decompression, including anterior decompression in one patient with basilar invagination; all 10 patients had significant improvement at 4-year mean follow-up visits (P < 0.0001). In 12 patients with syringomyelia, 5 were symptomatic from syringomyelia only, 6 were symptomatic from both brain stem compression and syringomyelia, and 1 was symptomatic from brain stem compression only. The median length of symptoms before presentation was longer for patients with syringomyelia than for patients without (2 yr versus 9 mo; P < 0.025); the mean follow-up was 4 years. Surgical procedures included posterior brain stem decompression in 12 patients, plugging of the obex in 7, and placement of syringosubarachnoid shunts in 7, a syringopleural shunt in 1, and fourth ventricular stents in 2. In the 12 patients with syringomyelia, symptoms from brain stem compression dramatically improved with surgical decompression (P < 0.025), whereas symptoms from syringomyelia less dramatically improved or stabilized. The slight improvement or stabilization of syrinx symptoms represents a successful result, given the documented progressive nature of syringomyelia in this group. We conclude that surgical treatment for the Chiari I malformation can stabilize or slightly improve the symptoms attributed to syringomyelia and dramatically relieve the symptoms of brain stem compression. Furthermore, early diagnosis and treatment are critical in obtaining the best outcome for the patient.

Adolescent↗
PubMed1995

Comparison of conventional and skull base surgical approaches for the excision of trigeminal neurinomas.

Trigeminal neurinomas have traditionally been excised through conventional approaches. Because symptomatic tumor recurrence exceeds 50% after conventional procedures, the authors evaluated the use of skull base approaches to achieve complete resection and a lower rate of symptomatic recurrence. Comparisons of skull base with conventional approaches to trigeminal neurinomas have been limited to small series with short-term follow-up periods. The authors reviewed their experiences with conventional (frontotemporal transsylvian, subtemporal-intradural, subtemporal-transtentorial, and suboccipital) and skull base (frontotemporal extradural-intradural, frontoorbitozygomatic, subtemporal anterior petrosal, and presigmoid posterior petrosal) surgical approaches for the excision of trigeminal neurinomas. In this paper they report the results of 15 patients with trigeminal neurinoma who underwent 27 surgical procedures between 1980 and 1990. Seventeen of the procedures used conventional and 10 used skull base approaches. All patients had tumors arising from Meckel's cave and the porus trigeminus either initially or on recurrence. Tumors located in the cavernous sinus recurred most frequently (83%); other tumors that recurred frequently were those located in Meckel's cave and the porus trigeminus (67%), and the posterior fossa (17%). The tumor extended into the anterolateral wall of the cavernous sinus in 38% of patients with cavernous sinus involvement. Tumor exposure and ease of dissection were superior with skull base approaches. Residual or recurrent tumors were found in 65% of patients following conventional approaches compared with 10% of patients following skull base approaches. Using skull base approaches, the surgeon was more accurate (90%) in estimating tumor excision than when using conventional approaches (43%). Perioperative complications were similar with both. The authors discuss the indications, advantages, and limitations of each approach. Based on anatomical considerations, they propose a strategy to best resect these tumors.

Adolescent↗
PubMed1995

Evidence of meningioma infiltration into cranial nerves: clinical implications for cavernous sinus meningiomas.

Anatomical and biological studies of cavernous sinus meningiomas help us understand the biological heterogeneity of these tumors. The question of whether cavernous sinus meningiomas infiltrate cranial nerves is clinically important because of the effect on treatment planning. In the authors' experience of treating 36 patients with cavernous sinus meningiomas, tumor invasion into a cranial nerve was documented in two patients in whom a cranial nerve was resected during the cavernous sinus dissection. In both patients, histological examination using hematoxylin and eosin and bodian stains showed infiltration of the cranial nerves by a benign meningioma which, to the best of the authors' knowledge, is a condition previously unreported. This histological finding of meningioma invasion into a cranial nerve demonstrates the biological heterogeneity of cavernous sinus meningiomas and raises concern about the invasive character of meningioma. Because not all tumor cells can be identified radiologically or by direct visualization at surgery, occult tumor infiltration predisposes a patient to recurrence despite the best neurosurgical efforts. Evidence of cranial nerve infiltration by meningioma suggests that, in some circumstances, cavernous sinus dissection in the hope of total removal of a meningioma may be futile and, in the long term, may provide no advantage over treatment options with lower morbidity.

Adult↗
PubMed1995

Evidence for clonal spread in the development of multiple meningiomas.

Meningiomas are common intracranial tumors that arise from the arachnoid cells of the meninges. Occasionally patients develop multiple meningiomas. Because the underlying mechanism of multiple meningioma formation is unknown, the authors examined the pattern of X chromosome inactivation in multiple meningiomas. Fifteen intracranial meningiomas were resected in four patients with multiple meningiomas to determine whether the tumors in patients with multiple meningiomas originate from a common progenitor cell or arise independently. Specimens were examined using polymerase chain reaction assays to detect the pattern of X chromosome inactivation. In each patient, all tumors showed inactivation of the same X chromosome, suggesting that tumors arose from the same clone of cells (p < 0.0005). The authors conclude that multiple meningiomas arise from the uncontrolled spread of a single progenitor cell.

Alleles↗
PubMed1995

A prospective 15-year follow up of 154 consecutive patients with trigeminal neuralgia treated by percutaneous stereotactic radiofrequency thermal rhizotomy.

There is a lack of prospective studies for the long-term results of percutaneous stereotactic radiofrequency rhizotomy (PSR) in the treatment of patients with trigeminal neuralgia. The authors present results in 154 consecutive patients with trigeminal neuralgia treated by PSR and prospectively followed for 15 years. Ninety-nine percent of the patients obtained initial pain relief after one PSR. Dysesthesia occurred in 31 patients (23%): in 7% with mild initial hypalgesia; in 15% with dense hypalgesia; and in 36% with analgesia. Dysesthesia was mild and did not require treatment in most patients. The corneal reflex was absent or depressed in 29 patients, and keratitis developed in three patients. In 19 of 22 patients with trigeminal motor weakness, the paresis resolved within 1 year. Of 33 patients who had pain recurrence, 10 patients had pain that was mild or controlled with medications, and 23 patients required additional surgical treatment. The authors estimated using Kaplan-Meier analysis that the 14-year recurrence rate was 25% in the total group: 60% in patients with mild hypalgesia, 25% in those with dense hypalgesia, and 20% in those with analgesia. Timing of pain recurrence varied according to the degree of sensory loss. All pain recurrences in patients with mild hypalgesia occurred within 4 years after surgery; 10% more of the patients with dense hypalgesia had pain recurrences within the first 10 years compared with patients with analgesia. The median pain-free survival rate was 32 months for patients with mild hypalgesia and more than 15 years for patients with either analgesia or dense hypalgesia. Of the 100 patients followed for 15 years after one or two PSR procedures, 95 patients (95%) rated the procedure excellent (77 patients) or good (18 patients). The authors conclude that PSR is an effective, safe treatment for trigeminal neuralgia. Dense hypalgesia in the painful trigger zone, rather than analgesia, should be the target lesion.

Adult↗
PubMed1995

Proximal-to-distal facial amplitude ratios as predictors of facial nerve function after acoustic neuroma excision.

Electrophysiological studies (for example, electroneuronography, nerve action potentials, absolute amplitudes of the muscle compound action potentials, and stimulation thresholds) do not accurately predict facial nerve function after the excision of acoustic neuromas. To eliminate individual nerve variability, the authors measured the ratio of the amplitudes of muscle compound action potentials produced by stimulating the facial nerve at the brainstem proximally and at the internal auditory meatus near the transverse crest distally after total tumor excision in 20 patients. The mean tumor size was 36 mm. The facial nerves were anatomically intact in all patients after tumor excision. The follow-up period ranged from 14 to 28 months. Facial nerve outcome was determined by a modified House-Brackmann grading scale. Initial facial nerve function was measured at Days 4 to 7 postoperatively, and final function was the grade at last follow up. The following results were obtained: all patients with proximal-to-distal amplitude ratios greater than 2:3 had Grade III or better initial function and Grade I final facial nerve function; 90% of patients with amplitude ratios between 1:3 and 2:3 had Grade III or worse initial facial nerve function, and 100% of these patients had Grade III or better final facial nerve function; all patients with amplitude ratios less than 1:3 had Grade IV or worse initial and final facial nerve function. The authors conclude that the proximal-to-distal amplitude ratios after acoustic neuroma excision can accurately predict postoperative facial nerve function.

Action Potentials↗
PubMed1995

Adult choroidal vein of Galen malformation.

We report staged embolization and stereotactic radiation in a true adult choroidal vein of Galen malformation. Management dilemmas and their resolutions are also discussed.

Adult↗
PubMed1995

Treatment of aneurysms of the internal carotid artery by intravascular balloon occlusion: long-term follow-up of 58 patients.

Long-term evaluation of patients with aneurysms of the internal carotid artery (ICA) treated by intravascular balloon occlusion has not been reported. From 1977 to 1992, 58 patients (age 14 to 81 years) with ICA aneurysms were treated at our institution by this technique. The aneurysms included 40 intracavernous carotid, 5 petrous carotid, 3 cervical carotid, and 10 ophthalmic segment aneurysms. Presenting symptoms were caused by mass effect in 45 patients, transient ischemia or cerebral infarction as a result of emboli in 6, subarachnoid hemorrhage in 4, and epistaxis in 3. Preoperative temporary balloon occlusion of the ICA combined with cerebral blood flow monitoring and induced hypotension were used to determine tolerance for occlusion. Two patients not tolerating test occlusion required an extracranial-intracranial bypass procedure, and another patient underwent extracranial-intracranial bypass prior to test occlusion because of contralateral ICA stenosis. In 55 patients, aneurysms were excluded from the circulation by either occluding the proximal ICA or trapping the aneurysm neck. In three patients, the aneurysm was directly obliterated with intravascular balloons with preservation of the parent ICA. Three patients died during treatment, one from subarachnoid hemorrhage and two from cerebral infarction. Mean follow-up was 76 months (range, 6 months to 15 years). Six patients who developed transient ischemia caused by emboli responded to volume expansion and anticoagulation treatment. Two patients developed a delayed infarction, and one patient developed aneurysm enlargement that required surgical clipping and obliteration. (ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Aneurysm formation after carotid occlusion.

We present two cases of subarachnoid hemorrhage caused by aneurysm development and enlargement in the anterior communicating artery complex. The cases occurred in a series of 58 balloon occlusions for unclippable giant aneurysms of the internal carotid artery.

Aneurysm↗
PubMed1994

Dural cavernous angiomas outside the middle cranial fossa: a report of two cases.

Cavernous angiomas of the dura mater are clinically and radiographically distinct from parenchymal cavernous angiomas. In this report, we present two cases of dural cavernous angiomas located outside the middle cranial fossa. The first patient is a 36-year-old woman with two dural cavernous angiomas, including one that enlarged during a 2-year period of observation. The second patient is a 33-year-old man with medically intractable seizures from a dural cavernous angioma of the convexity, which was discovered at autopsy. From our experience and a review of the literature, we have identified two groups of dural cavernous angiomas that differ in incidence, natural history, and surgical management. Most dural cavernous angiomas arise from the middle fossa; in contrast, only 15 cases of dural cavernous angiomas outside the middle fossa have been reported. Those in the middle fossa are more clinically aggressive and more difficult to resect surgically, because they grow toward the cavernous sinus and the parasellar region. Most patients with dural cavernous angiomas outside the middle fossa present with headaches, whereas those patients with dural cavernous angiomas in the middle fossa present with ocular signs, visual field defects, endocrinopathy, and trigeminal symptoms. Radiographically, both of the angiomas resemble meningiomas. Because of their intimate association with the cavernous sinus, surgical resection of middle fossa cavernous angiomas often is incomplete and may require postoperative radiosurgery to control growth. In contrast, angiomas in other locations are easily and successfully resected with little blood loss. The location of dural cavernous angiomas is an important factor in making the surgical decision and in predicting the outcome.

Adult↗
PubMed1994

Intraoperative monitoring of the vagus nerve during intracranial glossopharyngeal and upper vagal rhizotomy: technical note.

Intracranial section of the glossopharyngeal and upper vagal rootlets for the treatment of vagoglossopharyngeal neuralgia may cause dysphagia or vocal cord paralysis from injury to the motor vagal rootlets in 10% to 20% of cases. To minimize this complication, we recently applied a technique of intraoperative monitoring of the vagus nerve (previously described by Lipton and McCaffery to monitor the recurrent laryngeal nerve during thyroid surgery) in a patient undergoing intracranial rhizotomy for vagoglossopharyngeal neuralgia. By inserting an electrode in the ipsilateral false vocal cord and stimulating the rostral vagal rootlets intraoperatively under general anesthesia, we could differentiate the rostral vagal motor rootlets from the sensory rootlets. In this patient, the technique allowed us to preserve a rostral vagal rootlet, which if sectioned, could have caused dysphagia or vocal cord paralysis. We conclude that intraoperative monitoring of the rostral vagal rootlets is an important technique to minimize complications of upper vagal rhizotomy.

Adult↗
PubMed1994

Transpetrosal access to meningiomas juxtaposing the temporal bone.

Meningiomas arising from the petroclival dura have presented a challenge to both otolaryngologists and neurosurgeons. Access by means of subtemporal, suboccipital, translabyrinthine, or transcochlear routes have inherent limitations both surgically as well as from resultant morbidity. Since 1988, the authors have used a transpetrosal transtentorial (combined subtemporal suboccipital presigmoid) approach to these lesions in selected cases. The goals of this technique have been to preserve function of the cranial nerves, to avoid excessive retraction of the temporal lobe and cerebellum, and to eliminate damage to the venous sinus and Labbés vein. Exposure of the base of the tumor for ablation of the blood supply and access for tumor removal is an important advantage of this approach.

Adult↗
PubMed1994

Feeding artery pedicle aneurysms: association with parenchymal hemorrhage and arteriovenous malformation in the brain.

The association between arteriovenous malformations (AVM's) and aneurysms is well documented in the literature. However, a specific type of aneurysm, termed a "pedicle" aneurysm, has received little attention despite its role as a primary source of hemorrhage. The authors report four recent cases of patients with cerebral AVM's who bled from aneurysms arising from the midportion of AVM-feeding artery pedicles. Angiography, computerized tomography, and magnetic resonance imaging confirmed the origin of the hemorrhage from the pedicle aneurysm in each case. Because pedicle aneurysms are at risk for recurrent rupture, they represent an important subclassification of aneurysms associated with AVM's. The authors have expanded the previous classification systems for aneurysms associated with AVM's to include pedicle aneurysms; this classification is based on the location of the aneurysm and its relationship to the malformation. Complete documentation of such aneurysms as the potential source of hemorrhage is recommended, and prompt intervention by embolization and/or surgical resection is indicated for this dangerous aneurysm associated with cerebral AVM's.

Adult↗
PubMed1994

Surgical resection of third ventricle colloid cysts. Preliminary results comparing transcallosal microsurgery with endoscopy.

It is still not determined which is the best surgical option for third ventricle colloid cysts. Since 1990, the authors have used a steerable fiberscope to remove colloid cysts in seven patients and have performed microsurgery via a transcallosal approach in eight patients. The two techniques were compared for operating time, length of hospital stay, incidence of complications, recurrence, and hydrocephalus, and days spent recuperating before return to work to determine if endoscopic removal of colloid cysts is a safe and effective alternative to microsurgery. Statistical analysis was adjusted for age, sex, and presenting symptoms. Microsurgical cases averaged 206 minutes of operating time whereas endoscopic cases averaged 127 minutes (p = 0.01). For combined days spent in the intensive care unit and on the ward, the patients averaged 9.5 days after microsurgery and 4 days after endoscopy (p = 0.05). Postoperative complications occurred in five of eight patients after microsurgery and in one of seven patients after endoscopy (p = 0.09); complications were transient and primarily related to short-term memory loss. In all patients, preoperative symptoms resolved and the cysts have not recurred. Postoperatively, one patient required a ventriculoperitoneal shunt after microsurgery but all patients were shunt-independent after endoscopy. Patients returned to work an average of 59 days after discharge following microsurgery compared with an average of 26 days after endoscopy (p = 0.05). Compared with transcallosal microsurgery for the removal of colloid cysts, these preliminary results show that a steerable endoscope reduced operating time and that patients spent fewer days in the hospital and returned to work sooner after endoscopy.

Adolescent↗
PubMed1994

Management of tentorial dural arteriovenous malformations: transarterial embolization combined with stereotactic radiation or surgery.

The clinical, anatomical, and radiological features of nine cases of tentorial dural arteriovenous malformations (AVM's) are presented, and 45 reported cases are reviewed. Unlike dural AVM's of the transverse sigmoid and cavernous sinuses that usually have a benign natural history, dural AVM's of the tentorium typically present with hemorrhage or progressive neurological deficit. In this series, patients ranged in age from 52 to 72 years and included five men and four women. These patients presented with subarachnoid hemorrhage, parenchymal hemorrhage, brainstem dysfunction, cerebellar signs, and obstructive hydrocephalus. Malformations were fed principally by the meningohypophyseal trunk, branches of the middle meningeal artery, and the occipital artery. Venous drainage was uniform through the cortical veins (predominantly the mesencephalic, petrosal, and cerebellar veins). Eight of the nine patients had an associated venous aneurysm(s); two had more than one venous aneurysm, and two patients had a vein of Galen aneurysm associated with the tentorial dural AVM. Eight of nine patients improved after treatment, including four patients with complete obliteration of the dural AVM. Based on our experience, we have developed a treatment protocol for tentorial dural AVM's that uses transarterial embolization followed by direct microsurgery or stereotactic radiation. These therapies, applied in a staged manner, have proven safe and relatively effective for the treatment of dural AVM's.

Aged↗
PubMed1993

Recovery of vision after transcranial decompression of pituitary apoplexy characterized by third ventricular hemorrhage.

The authors present a case of pituitary apoplexy characterized by massive third ventricular hemorrhage. This rare complication, which caused total blindness in the patient, a 67-year-old man, was treated with transcranial decompression of the pituitary tumor and removal of a blood clot from the third ventricle. After surgery, the patient totally recovered his vision. To the best of our knowledge, this is the first case of a patient with pituitary apoplexy that ruptured into the third ventricle (diagnosed by imaging studies) who was treated by emergency transcranial decompression.

Adenoma↗