Glomus jugulare tumours: certain clinical and radiological aspects observed following Gamma Knife radiosurgery.

INTRODUCTION: Glomus jugulare tumours represent a great therapeutic challenge. Previous papers have documented good results from Gamma Knife surgery (GKS) with these tumours. However, the relationship between clinical improvement and tumour shrinkage has never been assessed. MATERIALS AND METHODS: There were 14 patients, 9 women and 5 men. The mean follow-up period was 28 months (range 6 to 60 months). All the tumours except one were Fisch type D and the mean volume was 14.2 cm(3) (range 3.7-28.4 cm(3)). The mean prescription dose was 13.6 Gy (range 12-16 Gy). RESULTS: None of the tumours have continued to grow. Eight are smaller and 6 unchanged in volume. Two patients with bruit have had no improvement in their symptoms. Among the other 12 patients, 5 have had symptomatic improvement of dysphagia, 4 in dysphonia, 3 in facial numbness, 3 in ataxia and 2 in tinnitus. Individual patients have experienced improvement in vomiting, vertigo, tongue fasciculation, hearing, headache, facial palsy and accessory paresis. One patient developed a transient facial palsy. Symptomatic improvement commonly began before any reduction in tumour volume could be detected. The mean time to clinical improvement was 6.5 months whereas the mean time to shrinkage was 13.5 months. CONCLUSIONS: Gamma Knife treatment of glomus jugulare tumours is associated with a high incidence of clinical improvement with few complications, using the dosimetry recorded here. Clinical improvement would seem to be a more sensitive early indicator of therapeutic success than radiological volume reduction. Further follow-up will be needed.

Adverse radiation effects after Gamma Knife Surgery in relation to dose and volume.

INTRODUCTION: The relationship between target volume and adverse radiation effects (AREs) at low prescription doses requires elucidation. The development of AREs in three series of patients treated in the Gamma Knife is analysed in relation to prescription dose and target volume. MATERIALS AND METHODS: There were three groups. In group 1, there were of 275 patients with meningiomas; in group 2, 132 patients with vestibular schwannomas; and in group 3, 107 patients with arteriovenous malformations (AVMs). The minimum follow-up for each group was more than 24 months. All patients were followed up at six monthly intervals. The patients with tumours received a prescription dose of 12 Gy, which was varied to protect normal structures but not in relation to tumour volume per se. The desired AVM prescription dose was 25 Gy, but this was also reduced to protect normal structures and to keep the total dose within certain pre-defined limits. All AREs refer to intra-parenchymal increased perilesional T2 signal on MR irrespective of clinical correlation. RESULTS: There was no relationship between tumour volume and the development of ARE in the tumour groups. There was a highly significant relationship between target volume and the development of ARE for the AVMs with their much higher dose. Radiation-induced clinical trigeminal and facial nerve deficits with both vestibular schwannomas and meningiomas were always associated with an increased T2 signal in the neighbouring brainstem parenchyma. CONCLUSIONS: The relationship between target volume and the risk of adverse radiation effects may not apply with lower prescription doses. Individual radiosensitivity may explain why a minority suffer AREs unrelated to target volume. It is possible that radiation-induced brainstem parenchymal damage with concomitant cranial nerve deficits may be commoner after radiosurgery than is usually thought. If tumour control with lower doses is adequate, radiosurgery could be safely considered for larger targets associated with a high risk from microsurgery.

Gamma Knife surgery of large meningiomas: early response to treatment.

PURPOSE: Gamma Knife treatment is traditionally limited to tumours with a diameter not exceeding 3-3.5 cm. The current paper presents 97 patients with meningiomas with a minimum volume of 10 cm(3), treated with a prescription dose of 12 Gy (or sometimes less to protect neighbouring structures). The post-treatment assessment of these patients, the early response to treatment and the complications of treatment are presented. METHODS: There were 97 patients, 70 females and 27 males. The mean age was 48.1 years (range 20.4-87.2 years). The mean follow-up was 54 months (range 25-86 months). All tumours had a volume of 10 cm(3) or more. The mean volume was 15.9 cm(3) (range 10.0-43.2 cm(3)). Post-treatment follow-up used quantitative and qualitative assessments, which are described. RESULTS: No tumour continued to grow. Twenty-seven were smaller and 72 unchanged in volume. Three patients suffered adverse radiation effects (defined as a new post-treatment oedema detected on the magnetic resonance image with or without contrast leakage). In one case this was silent. In two cases the clinical and radiological effects were temporary and resolved completely. CONCLUSIONS: It is suggested on the basis of this material that the dosimetry used here permits the safe Gamma Knife treatment of larger meningiomas within the range reported. The early radiological response is encouraging, but further follow-up is needed to check long term tumour control. A qualitative method of tumour volume assessment is presented. It seems to be a simpler and more reliable way of assessing tumour volume changes than other methods currently in routine use.

A six year experience with the postoperative radiosurgical management of pituitary adenomas.

Since April 1992, 73 consecutive patients with pituitary adenomas were treated with radiosurgery. There were 31 hormonally inactive adenomas and 42 hormonally active adenomas. All but three patients had been subjected to one or more surgical procedures prior to radiosurgery. Three patients had received fractionated radiotherapy. In the inactive adenoma group, the mean target volume was 4.4 ¿ 3 cm3 and the mean prescription dose was 13.8¿1.5 Gy. In the prolactinoma patients, the mean target volume was 6.7 ¿ 9 cm3 and the mean prescription dose was 14.2 ¿4 Gy. In the acromegalic patients, the mean target volume was 2.9¿2.5 cm3 and the mean prescription dose was 16¿4 Gy. ACTH secreting adenomas had a mean target volume of 3.6 ¿ 5.5 cm3 with a mean prescription dose of 17 ¿4.8 Gy. The mean follow-up time was 28.9 ¿ 21.5 months. Follow-up data was available in 83.6% of the patients. Tumor control was achieved in 98.3% and the endocrinological cure rate was 57%. Pituitary function deteriorated in 19.2%. No patient suffered from radiation induced visual damage. It would seem that postoperative radiosurgery for residual or recurrent pituitary adenomas may be a safe technique that can increase the frequency of therapeutic success.

Cavernous sinus meningiomas--what is the strategy: upfront or adjuvant gamma knife surgery?

43 patients with meningiomas of the cavernous sinus form the basis of this study. Two patients were treated with microsurgery alone, 17 patients were treated by Gamma Knife radiosurgery (GKRS) as a primary treatment modality, and 24 patients underwent a combined treatment of microsurgery followed by GKRS. Therefore, in 17 patients the diagnosis rested on clinical and radiological criteria alone. Cranial nerve disorders (CND) related to open surgical treatment were infrequent in this material (3 of 13 patients) due to deliberate strategies of partial or subtotal resection aimed at sparing cranial nerves from surgical maneuvers. In contrast, 6 of 11 patients, admitted for GKRS from other institutions suffered from considerable CND after open surgery and showed only partial improvement after GKRS. In all GKRS cases, no radiation-related complications were seen after a follow-up of 18-62 months (mean 39 months). Moreover, in all cases tumor control was obtained with a stable tumor volume in 63%, reduction of volume in 34.5% and a disappearance of tumor in 2.5%. GKRS is not only an additional treatment for meningiomas involving the cavernous sinus, but may be offered to the patient as an alternative primary treatment.

Acoustic neurinomas with macrocysts treated with Gamma Knife radiosurgery.

Six cases of acoustic neurinomas with macrocystic components are presented. In three cases the cystic portion was within the tumor, while in the other three, the cyst was peritumoral, in the form of a cul-de-sac within the arachnoid, in other words it was not a true tumor cyst. The six tumors are from a series of 74 acoustic neurinomas treated by radiosurgery with a minimum follow-up of 18 months. In all cases, enlargement of the associated cyst was observed as early as 4 months after radiosurgery. Clinical signs and symptoms such as facial weakness, trigeminal symptoms, vertigo and dizziness and coordination disorders developed between 4 and 8 months. In three cases (two intramural cysts and one combined peri- and intramural cyst), subacute microsurgery was performed to treat the progression of neurological symptoms. One case had spontaneous rupture of an intramural cyst, one case of a peritumoral cyst, after progression showed a slow spontaneous size decrease after 2 years, and one case is still under observation. In the reported series, the dose at the tumor margin ranged between 11 and 17 Gy (mean 13.8 +/- 2.5 [SD] Gy) and the maximal dose between 24 and 40 Gy (mean 30.6 +/- 6.2 Gy). In view of the findings in this study, one should perhaps be cautious in advising radiosurgery for this subgroup of acoustic tumors.

Radiation-induced edema after Gamma Knife treatment for meningiomas.

A retrospective study was performed to analyze some parameters in a consecutive series of 35 Gamma Knife treatments in 34 patients with benign meningiomas. The minimum dose to the tumors was never less than 12 Gy. The follow-up period was from 1 to 3 years. A semiquantitative method of tumor volume assessment was used to measure the tumor response to treatment. The presence and clinical significance of postradiation edema were noted. Even in this short follow-up period, 11 of the 35 tumors were reduced in volume. No tumors increased in size. Edema developed preferentially in nonbasal tumors, especially those around the midline and sagittal sinus. In all but one case where radiation-induced edema was observed was the margin tumor dose 18 Gy or more. It is suggested that doses of 18 Gy or more should probably be avoided in the Gamma Knife treatment of meningiomas and that the greatest care should be taken in selecting non-skull base tumors for this form of treatment.

Tumour volume reduction following gamma knife radiosurgery: the relationship between X-ray and histological findings.

The case histories of two young ladies with Cushing's disease are described. Both patients were treated first with Gamma Knife radiosurgery and subsequently by microsurgery. The radiosurgery caused a marked reduction in tumour volume but only a partial relief of the endocrinopathy. Comparison of the histological findings with the radiological findings following radiosurgery indicates that confluent necrosis is not a prerequisite for a reduction in tumour volume. It seems more likely that the reduction in tumour volume is related to changes in cellular dynamics.

Radiosurgical treatment of gliomas of the diencephalon.

The results of Leksell Gamma Knife treatment of diencephalic gliomas are presented. Eight tumours in seven patients form the basis of this report. 7 patients, 4 males and 3 females. The age range was 7.5 to 33 years with a mean of 18 years. Mean follow-up was 21 +/- 12 months. In 4 patients the tumour had been reduced in volume by an open internal decompression procedure. The location of the tumour will determine the risks of treatment. With anterior lesions there is risk of endocrinological and visual pathway damage. With a pineal region lesion there is a risk of diplopia. In this series no tumour has increased in volume. Four have decreased and one has disappeared. Two patients suffered temporary diplopia. No visual disturbance has been observed to date. No hypothalamic disturbance has been observed yet. These tumours are dangerous not so much because of their biological nature as because of their location. However, the biological nature of the tumours, with the close concordance between the radiological and actual extent make them appropriate targets for radiosurgery as a primary treatment. The present study gives preliminary support to this line of treatment.

Changes in intracranial morphology, regional cerebral water content and vital physiological variables during epidural bleeding. An experimental MR study in dogs.

Epidural bleeding was produced in 8 anaesthetised and heparinised dogs by an artificial system. Changes in vital physiological variables were related to intracranial shifts and tissue water content assessed with MR imaging. Six animals survived while 2 succumbed. In the surviving animals intracranial shifts and compressions remained unchanged from an early stage. The cerebral perfusion pressure was reduced from between 80 and 110 mm Hg to between 40 and 60 mm Hg. Some increase in supratentorial white matter tissue water was observed. In the lethal experiments cerebral perfusion pressure fell to less than 40 mm Hg. Moreover, secondary delayed anatomical changes were seen including hydrocephalus. Increase in cerebral tissue water was more intense and widespread than in the survivors. These findings indicate that the outcome of epidural bleeding is related to cerebral perfusion pressure with secondary deterioration resulting from additional volume loading from increased tissue water and hydrocephalus.

Progressive brain compression. Changes in vital physiological variables, correlated with brain tissue water content and brain tissue displacement. Experimental MR imaging in dogs.

Continuous recording of vital physiological variables and sequential MR imaging were performed simultaneously during continuous expansion of an epidural rubber balloon over the left hemisphere in anaesthetised dogs. Balloon expansion led to a progressive and slightly nonlinear rise in intracranial CSF pressures and a fall in local perfusion pressures. Changes in systemic arterial pressure, pulse rate, and respiration rate usually appeared at a balloon volume of 4% to 5% of the intracranial volume (reaction volume), together with a marked transtentorial pressure gradient and MR imaging changes consistent with tentorial herniation. Respiratory arrest occurred at a balloon volume of approximately 10% of the intracranial volume (apnoea volume), which was associated with occlusion of the cisterna magna, consistent with some degree of foramen magnum herniation. Increase in tissue water was observed beginning at approximately the reaction volume, presumably due to ischaemic oedema, due to the fall in perfusion pressures.

Dose planning with the Leksell Gamma Knife: the effect on dose volume of more than one shot at the same target point.

A study was made of the interaction between Gamma Knife shots of different diameters, located at the same target coordinates. The effect of the doses was calculated by the Kula program and confirmed by film dosimetry. It could be shown that intermediate collimator sizes can be simulated in this way, so that, for example, a 4- and 8-mm shot with the same target coordinates simulates a 6-mm collimator. A coaxial 8- and 14-mm shot simulates an 11-mm collimator and a coaxial 14- and 18-mm shot simulates a 16-mm collimator. Additional intermediate collimator sizes can be simulated by changing the weighting of the two coaxial shots. The sharpness of the dose fall of the simulated coaxial shots is of the same order as that of single shots, indicating that the technique does not depart from ordinary Gamma Knife technique in any significant way.

The results of Gamma Knife surgery of meningiomas, related to size of tumor and dose.

In Bergen, 20 patients with meningiomas have been treated with a follow-up period in excess of 1 year. While this is too short a period to allow more than tentative conclusions to be drawn, some trends can be determined nonetheless. There has been some variation in the reporting of the results of treatment of meningiomas, with one group producing a reduction in size in 7% of patients and another in 34%. In the current material, 10 patients received 10 Gy or less to the edge of the tumor. In 4 of these 12 patients there was increase in the volume of the tumor within 1 year of treatment. Ten of the patients received 12 Gy or more to the edge of the tumor. Of these 10 patients, 4 had tumors which showed a reduction in volume. It is suggested that the difference in the reported rate of tumor volume reduction is related to differences in dose, which is discussed in relation to other treatment parameters.

The effects of Gamma Knife surgery of pituitary adenomas on tumor growth and endocrinopathies.

Fifteen patients were treated in the Gamma Knife Unit and followed for 18 months or longer. Four patients had Cushing's disease, 4 had acromegaly, 3 had Nelson's syndrome and 3 had prolactinomas. One patient had no endocrinopathy. One of the patients with acromegaly and 2 of those with prolactinomas had been operated prior to Gamma Knife treatment. Radiological tumor localization was not an insuperable problem in this series. The effect of Gamma Knife treatment on the anterior pituitary neoplasia, as such, was consistently successful. All the tumors which received 10 Gy or more to the edge showed either a reduction in volume or at least cessation of growth. On the other hand, the effect of the treatment was less consistent in respect to the endocrinopathies. These results are discussed in respect of dose and tumor size. It is suggested that the role of the Gamma Knife in the treatment of pituitary adenomas requires further clarification, based on prospective studies.

[Intraspinal epidural hematomas. Treatment and prognosis]. / Intraspinale epidurale hematomer. Behandling og prognose.

The results of treatment in 26 patients with spinal epidural haematoma are analysed in respect of pre-operative factors related to prognosis. The material consists of the two patients treated at Haukeland Hospital since 1980 and 24 patients described in the literature over the same period. This condition affects people of all ages. It should be suspected in cases of sudden excruciating spinal pain and progressive paraparesis. Factors with a poor prognosis were a haematoma covering many spinal levels and having a thoracic localization. To a lesser extent, a greater degree of preoperative neurological deficit and a longer duration from symptom debut to operation had a negative effect on prognosis. These patients require speedy diagnosis before total paralysis is established. They should be operated as soon as possible.

[Radiosurgery. A different kind of neurosurgery]. / Strålekirurgi. Et annerledes prinsipp i neurokirurgi.

A Leksell Gamma Knife has been used at Haukeland Hospital, Bergen, since October 1988. This is a powerful instrument in the treatment of some intracranial lesions. The article briefly describes the principles of treatment and the uses and limitations of the Gamma Knife.

Cerebral blood flow during experimental epidural bleeding in swine.

Regional cerebral blood flow (rCBF) was studied during an aggressive epidural bleed, using a ventilated swine model. rCBF, regional organ blood flow and cardiac output were measured using the radioactive microsphere technique. Blood flows were measured prior to the start of bleeding (Stage 1), when intracranial pressures had reached a plateau and supratentorial perfusion pressure was reduced by about 50% (Stage 2), and at isoelectric EEG (Stage 3). Supratentorial rCBF did not change significantly between stages 1 and 2 while rCVR decreased, implying autoregulatory activity. Cerebral ischaemia developed between stages 2 and 3 when rCBF values fell to levels between 20 and 50% of control values. Infratentorial rCBF changes were similar but less marked, so that adequate brain stem perfusion was maintained below the upper mesencephalon. The left temporal and left parietal cortex and upper mesencephalon suffered a greater reduction in rCBF than other regions, due to proximity to the haematoma and tentorial herniation. The supratentorial perfusion pressure at stage 2 was 60 mm Hg associated with a haematoma volume of 6% of the intracranial volume (ICV). The infratentorial perfusion pressure never fell below 60 mm Hg. The Cushing response was absent when the EEG became isoelectric. This is tentatively ascribed to the absence of hypoxia, because mechanical ventilation was used. Instead systemic arterial hypotension accompanied bleeding in this ventilated model. This hypotension was due to falling cardiac output and peripheral vasodilation.

A quantitative study of some factors affecting the outcome of experimental epidural bleeding in swine.

During an experimentally induced aggressive epidural bleed the effect on outcome of haematoma volume, cerebral perfusion pressures, intracranial pressure gradients and ventilation were examined in a swine model. Two groups of experiments were performed using either spontaneous ventilation (group 1, n = 6) or mechanical ventilation for 1 hour (group 2, n = 7). The preparations were otherwise identical. An animal was considered to have succumbed when the EEG became irreversibly isoelectric within a total follow-up time of 80 minutes. Mechanical ventilation had a marked effect on survival. All spontaneously ventilated animals succumbed, 4 of them in less than 60 minutes, the remaining 2 between 60 and 80 minutes after the start of bleeding. All mechanically ventilated animals survived for the 60 minutes while the ventilator was connected. Following disconnection 2 animals started to breathe spontaneously and survived the final 20 minutes of the 80 minutes of the follow-up time. The remaining 5 succumbed following apnoea. The size of haematoma did not differ significantly between the groups. Two additional factors, hypoventilation and a secondary rise in supratentorial pressure, contributed to a lethal outcome. Hypoventilation was an inevitable precursor of the isoelectric EEG. There was a close correlation between the development of hypoventilation and intracranial herniation. A secondary rise in supratentorial pressure, unrelated to ventilation, was seen after cessation of bleeding in 8/13 cases. It was associated with a falling supratentorial perfusion pressure and EEG attenuation, suggesting a secondary intracranial expansion, possibly due to oedema, hydrocephalus or both. It is concluded that mechanical ventilation in the acute stage of epidural bleeding may be of clinical value.(ABSTRACT TRUNCATED AT 250 WORDS)