Rare fatal vascular complication of transsphenoidal surgery

We report the case of a 61-year-old man, who underwent transsphenoidal surgery for a pituitary macroadenoma. The presence of tough fibrous septa dividing the tumour permitted only a partial resection. Progressive loss of consciousness soon after surgery occurred, an emergency CT scan showed no evidence of haemorrhage. Twenty hours later, MRI revealed compression of both internal carotid arteries with arrest of arterial flow resulting in stroke by an enlarged haemorrhagic mass consistent with a pituitary apoplexy. On the second postoperative day, the patient died as a result of this extensive stroke. The mechanisms of this rare complication after transsphenoidal surgery are theorized and the sensitivity of imaging methods is discussed.

The role of gamma knife radiosurgery in children

OBJECTS

Despite advances in microneurosurgery, the surgical management of deep-seated lesions is still associated with a high risk. Gamma knife radiosurgery (GKRS), however, has improved the outcome of cerebral tumors and arteriovenous malformations (AVMs) in delicate areas.

METHODS

Between March 1992 and June 1998, 50 children (age 1-16 years) with intracranial lesions were treated with GKRS. There were 12 low-grade gliomas, 12 high-grade gliomas, 7 craniopharyngiomas, 3 hamartomas, 2 meningiomas of the skull base, 2 vestibular schwannomas, 1 pituitary adenoma, 1 choroid plexus papilloma, and 10 AVMs. The mean size of the pathologies was 4.6 cm3 (range: 0.21-25.5 cm3). A mean marginal dose of 16 Gy (8-25 Gy) was applied to a mean isodose surface of 50% (35-90%). Clinical and neuroradiological follow-up were analyzed for outcome. Follow-up periods of 45 of these patients ranged from 8 to 79 months (mean 36 months); 5 patients were lost to follow-up. Neoplasms decreased in size in 15 cases (41%), remained unchanged in 13 patients (35%), and increased in 9 cases (24%). AVMs obliterated in 3 children (38%) within 24 months. Neurological follow-up demonstrated improved clinical status in 7 patients (15.5%), stable neurological status in 31 cases (69%) and clinical deterioration in 7 patients (15.5%). The treatment was well tolerated and no complications occurred.

CONCLUSIONS

GKRS represents a safe and effective treatment option for benign neoplasms or AVMs in pediatric patients and may extend survival times of children with malignant lesions.

Radiosurgery of glomus tumors: midterm results

Glomus tumors (GT) of the skull-base present a complex surgical challenge due to their delicate localization and specific vascular supply. This study is designed to evaluate the role of stereotactic radiosurgery in the treatment of GT. Thirteen patients with GT have been treated with the Gamma Knife. Radiosurgery was performed because of recurrences after surgical removal in six patients. Histology was not available in seven patients, thus, diagnosis was made from neuroradiological features only. Two of them had partial embolization before Gamma Knife treatment. Clinical and morphological data were collected from 11 patients, who had a representative follow-up of at least 12 months. Mean follow-up was 42 months (range 14 to 72 months). Within the follow-up period there was no tumor progression and no clinical deterioration in any of the patients. 64% of the patients had an improvement of their symptoms, and in 36% the volume of the lesion decreased in size. There was no radiation-related morbidity. It is suggested that radiosurgery seems to be safe and effective in the treatment of GT.

Corpus callosotomy with radiosurgery

OBJECTIVE

Corpus callosotomy is a surgical option for medically uncontrolled generalized epilepsy in appropriate patients. Because numerous complications related to open callosotomy are still reported, we performed radiosurgical corpus callosotomy with the gamma knife.

METHODS

Between October 1992 and June 1995, three patients underwent stereotactic radiosurgery to ablate the anterior third of the corpus callosum. The patients had intractable epilepsy: two had Lennox-Gastaut syndrome, and one had multifocal epilepsy with atonic, tonicoclonic, and atypical absence seizures. The history of seizures ranged from 20 to 37 years' duration. Stereotactic radiosurgery was performed with a cobalt-60 gamma knife using a 4-mm collimator, targeted to the rostrum, genu, and anterior third of body of the corpus callosum. Two patients were treated once with 150 and 160 Gy at maximum, respectively, and one patient was treated in two stages with 50 Gy and then 170 Gy at maximum.

RESULTS

The severity and frequency of seizures were significantly reduced in all three patients. The types of seizures associated with the most improved outcome were atonic and generalized tonicoclonic seizures. The mean follow-up period was 38 months. Hospitalization required for this procedure was 3 days. No complications related to irradiation were recorded except transient headache in one patient.

CONCLUSION

The outcomes suggest that radiosurgical corpus callosotomy may be a promising alternative treatment to open callosotomy.

Chronic spinal subdural haematoma associated with intracranial subdural haematoma: CT and MRI

Chronic spinal subdural haematoma is a uncommon. We describe the CT and MRI appearances of chronic spinal and intracranial subdural haematomas following minor trauma. The aetiology, pathogenesis and differential diagnosis are discussed.

Treatment of cerebral radionecrosis by hyperbaric oxygen therapy

Clinically observed adverse radiation effects (ARE) are rather uncommon, but modern imaging reveals that they are more common after radiosurgery than previously believed. Little is known about the pathogenesis, and current treatment is mostly empirical. The benefit of hyperbaric oxygen therapy (HBO) on radiation-induced bone and soft tissue necrosis is known in lesions in the maxillofacial area, the mouth and in the head and neck. HBO raises the tissue pO2 and initiates a cellular and vascular repair mechanism. This forms the basis for the hypothesis that it might also help alleviate the results of cerebral radionecrosis. This study is a preliminary attempt to test this hypothesis. Two patients with arteriovenous malformations (AVMs) were chosen for the study. They had been treated with Gamma Knife radiosurgery (GKRS) and had developed imaging signs consistent with ARE. They were treated by breathing 100% oxygen at 2.5 atmospheres absolute (250 kPa) in sessions of 60 minutes per day. This treatment was repeated 40 times in cycles of ten sessions. Both responded well to HBO, one lesion disappeared and the other was reduced significantly in size. No adjuvant steroids were given. These results give evidence that HBO has a potential value in treating ARE but further experience will be needed to confirm its definite benefit.

Intracranial aneurysms: a review of endovascular and surgical treatment in 248 patients

We reviewed the medium-term results of endovascular treatment of intracranial aneurysms and compared patient selection and results with those of open surgery. Between January 1992 and December 1995, a total of 248 consecutive patients were treated for 297 aneurysms (61 unruptured and 236 ruptured). 162 aneurysms in 142 patients (mean age, 48.5 years) were treated microsurgically and 134 aneurysms in 106 patients (mean age, 54.2 years) were treated by endovascular embolization with Guglielmi detachable coils (GDC). The mean follow-up was 2.6 years (range, 1.5 to 4.5 years). There was no significant difference in patient population and selection in terms of age, sex or location of aneurysms between both methods. Both modalities achieved excellent results (defined as no neurological deficit) in patients with unruptured aneurysms and with no or minor deficits after subarachnoid hemorrhage (SAH) between 71% and 88%. Patients with moderate deficits after SAH had excellent outcomes in 49% after open surgery, and 47% after embolization. Poor grade patients had, equally, as well an acceptable as a pour outcome, between 0% and 50%. There was no significant difference between the outcome of surgical or endovascular patients. We conclude that GDC embolization is not associated with a higher risk of morbidity and mortality than open surgery. This risk may even be lower for lesions in surgically unfavorable locations. The GDC technique is a less invasive, effective option to prevent re-bleeding in early stage, even in poor-grade patients. However, these encouraging medium-term results have to be confirmed by a longer observation period.

Dose-response tolerance of the visual pathways and cranial nerves of the cavernous sinus to stereotactic radiosurgery

As the number of patients treated with stereotactic radiosurgery increases, it becomes particularly important to define with precision adverse effects on distinct structures of the nervous system.

OBJECT

This study was designed to assess the dose-response tolerance of the visual pathways and cranial nerves after exposure of the cavernous sinus to radiation.

METHODS

A total of 66 sites in the visual system and 210 cranial nerves of the middle cranial fossa were investigated in 50 patients who had undergone gamma knife treatment for benign skull base tumors. The mean follow-up period was 40 months (range 24-60 months). Follow-up examinations consisted of neurological, neuroradiological, and neuroophthalmological evaluations. The actuarial incidence of optic neuropathy was zero for patients who received a radiation dose of less than 10 Gy, 26.7% for patients receiving a dose in the range of 10 to less than 15 Gy, and 77.8% for those who received doses of 15 Gy or more (p < 0.0001). Previously impaired vision improved in 25.8% and was unchanged in 51.5% of patients. No sign of neuropathy was seen in patients whose cranial nerves of the cavernous sinus received radiation doses of between 5 and 30 Gy. Because tumor control appeared to have been achieved in 98% of the patients, the deterioration in visual function cannot be attributed to tumor progression.

CONCLUSIONS

The structures of the visual pathways (the optic nerve, chiasm, and tract) exhibit a much higher sensitivity to single-fraction radiation than other cranial nerves, and their particular dose-response characteristics can be defined. In contrast, the oculomotor and trigeminal nerves have a much higher dose tolerance.

Basilar tip aneurysm: endovascular treatment with Guglielmi detachable coils--midterm results

PURPOSE

To determine the safety and effectiveness of Guglielmi detachable coils in the endovascular treatment of ruptured and nonruptured basilar tip aneurysms.

MATERIALS AND METHODS

A basilar tip aneurysm was occluded with Guglielmi detachable coils in 21 patients. The aneurysmal diameter was small (less than 12 mm) in 15 patients, large (12-25 mm) in four patients, and giant (more than 25 mm) in two patients. Angiographic follow-up ranged from 6 to 48 months (mean, 26 months); clinical follow-up ranged from 1 to 48 months.

RESULTS

Embolization was technically successful in all patients. Complete occlusion was achieved in 14 (67%) patients; 90% occlusion was achieved in seven (33%) patients. There was partial reperfusion of the aneurysm in three patients (14%) after 6 months, which necessitated repeated embolization. The clinical results were excellent in 13 patients, good in six, and fair in one. One patient died 2 months after the embolization due to pulmonary complications. A posterior cerebral artery was occluded in five (24%) patients; one of these patients developed a permanent neurologic deficit, one developed a transient neurologic deficit, and three had no clinical symptoms.

CONCLUSION

Endovascular treatment of a basilar tip aneurysm with Guglielmi detachable coils seems to be a safe and less invasive alternative to surgical clipping.

Complications after shunting isolated IV ventricles

An isolated IV ventricle in chronically shunted patients is being reported with increasing frequency. Complications associated with posterior fossa shunting, however, have seldom been described. Between January 1986 and December 1995, we treated 292 children younger than 16 years for hydrocephalus: 7 (2.4%) developed an isolated IV ventricle, and 5 of these were symptomatic with posterior fossa signs. These 5 patients required posterior fossa shunting, after which their neurological status improved. However, 1 week and 6 weeks after surgery, respectively, 2 patients developed new cranial nerve deficits related to a slit-like IV ventricle with secondary irritation of the brain stem by the IV ventricular catheter. Shortening the catheter and replacing the valve eliminated the cranial nerve palsies, implying that these complications were not caused by direct injury of the brain stem during placement of the shunt. Alternative surgical techniques and the use of different (flow-regulating) valves may avoid such complications.

Dynamic and static scintigraphic evaluation of cerebral arteriovenous malformations to evaluate radiosurgical treatment

The radiobiologic changes induced by cobalt-60 gamma irradiation in cerebral arteriovenous malformations (AVMs) is a torpid process. Complete obliteration may take 1 or 2 years or even longer. Neuroradiological modalities like magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) do not provide sufficient information to comprehend this process. Digital subtraction angiography represents an invasive method and is therefore most often performed when complete obliteration is expected. The purpose of this study was to investigate the value of blood pool scintigraphy and functional imaging, such as single photon emission computed tomography (SPECT), to gain more knowledge about the volumetric changes of AVMs treated by radiosurgery. Twenty consecutive candidates for Gamma Knife treatment were selected for comparative MRI/ MRA and scintigraphic studies. All lesions ranging from 0.6 to 18.6 cm3 could be identified on blood pool and SPECT images. Seven patients had repetitive examinations at 3-month intervals to compare the relative volumetric change of the lesion. In 5 cases, a marked decrease in blood pooling was noticed after 3 months, and in 2 patients no significant change was evident. In contrast, MRI/MRA scans done at the same time did not similarly indicate progressive obliteration changes. This preliminary result indicates that scintigraphic evaluation using the blood pool technique is a very sensitive method to describe the relative volumetric change of radiosurgically treated AVMs.

Localization of superficial cerebral lesions using a magnetic resonance imaging-guided localizer

The localization of superficial cerebral lesions may be difficult even if they reach the surface of the cerebral cortex. Intraoperative ultrasound often fails to detect subcortical lesions. A localization device using multiplanar MR-imaging has been designed to project such lesions to the scalp. This device is a hood-shaped grid made of polyethylene tubing filled with paramagnetic contrast agent. In this hemispherical grid the tubes are arranged at a distance of 15 to 30 mm so that the MR-plane always slices perpendicular to the axis of the tubing and depicts a bright spot per tube. It is rapidly filled prior to each MR-examination, placed on the patient's head, and taped to his forehead to avoid unintentional displacement during and after the examination until the projection of the lesion is marked on the skin.

Radiation sensitivity of visual and oculomotor pathways

Adverse effects of stereotactic radiosurgery on cranial nerves, especially the optic nerve and its pathways, are not yet sufficiently understood. 29 patients who underwent Gamma Knife radiosurgery for benign skull base tumors were reviewed. In all of them, parts of the visual pathways and/or other cranial nerves in the middle cranial fossa received significant doses of radiation. The dose given was correlated with neuro-ophthalmological findings during a follow-up period of 6-24 months. Cranial nerves III, IV and VI within the cavernous sinus, exposed to a dose from 4.5 to 30 Gy, did not develop signs of a neuropathy. Neither did the trigeminal nerve which received between 5 and 20 Gy. In patients with normal neuro-ophthalmological findings prior to radiosurgery, the visual pathways tolerated a dose between 7.5 to 15 Gy. However, in a group of patients with visual deficits before treatment and where the visual fibers received between 6 and 16.6 Gy, 31% deteriorated afterwards. These results indicate that the visual pathways are more at risk for radiation damage than the other cranial nerves in the region and that they may be even more vulnerable to radiation if prior to radiosurgery their function has been compromised by tumor or previous surgery.