Gamma knife capsulotomy for intractable OCD: Neuroimage analysis of lesion size, location, and clinical response

Obsessive-compulsive disorder (OCD) affects 2-3% of the population. One-third of patients are poorly responsive to conventional therapies, and for a subgroup, gamma knife capsulotomy (GKC) is an option. We examined lesion characteristics in patients previously treated with GKC through well-established programs in Providence, RI (Butler Hospital/Rhode Island Hospital/Alpert Medical School of Brown University) and São Paulo, Brazil (University of São Paolo). Lesions were traced on T1 images from 26 patients who had received GKC targeting the ventral half of the anterior limb of the internal capsule (ALIC), and the masks were transformed into MNI space. Voxel-wise lesion-symptom mapping was performed to assess the influence of lesion location on Y-BOCS ratings. General linear models were built to compare the relationship between lesion size/location along different axes of the ALIC and above or below-average change in Y-BOCS ratings. Sixty-nine percent of this sample were full responders (≥35% improvement in OCD). Lesion occurrence anywhere within the targeted region was associated with clinical improvement, but modeling results demonstrated that lesions occurring posteriorly (closer to the anterior commissure) and dorsally (closer to the mid-ALIC) were associated with the greatest Y-BOCS reduction. No association was found between Y-BOCS reduction and overall lesion volume. GKC remains an effective treatment for refractory OCD. Our data suggest that continuing to target the bottom half of the ALIC in the coronal plane is likely to provide the dorsal-ventral height required to achieve optimal outcomes, as it will cover the white matter pathways relevant to change. Further analysis of individual variability will be essential for improving targeting and clinical outcomes, and potentially further reducing the lesion size necessary for beneficial outcomes.

Radiation and regeneration: behavioral improvement and GDNF expression after Gamma Knife radiosurgery in the 6-OHDA rodent model of hemi-parkinsonism

BACKGROUND

Recent research has demonstrated that the adult mammalian CNS is capable of regeneration. This regeneration is often initiated as a response to thermal, chemical or mechanical injury. The effects of radiation on the mammalian CNS have also been found to aid in certain regeneration processes.

METHOD

In our project we examined the potential therapeutic value of radiation induced regeneration of diseased mammalian rat CNS. Eleven Sprague-Dawley rats with 6-hydroxy-dopamine (6-OHDA) induced hemi-parkinsonism were treated in the Leksell Gamma Knife using a single 4 mm collimator shot targeted to the ipsilateral (parkinsonian) caudate-putamen complex. A maximum dose of 140 Gy was used to create a necrotic lesion. Animals were tested behaviorally using the apomorphine-induced rotational behavior model before and up to 6 months after radiosurgery. Histochemical analysis was performed 2 weeks, 1 month and 4 months after radiosurgery. Histological sections were obtained and immunohistochemistry was performed for glial cell line derived neurotrophic factor (GDNF).

FINDINGS

The rotational behavior for 11/11 animals (100%) was found to initially worsen at 2 weeks and 4 weeks after radiosurgery before a statistically highly significant reduction in apomorphine induced rotations was observed at 2, 3, and 4 months after radiosurgery (83% reduction by month four; p < 0.0001). For 2/11 animals the rotational behavior almost disappeared indicating near-abolition of parkinsonian behavior. On histological examination, the lesions were easily identified as areas of necrosis about 4 mm in diameter. The region immediately adjacent to the lesion was found to have highly positive expression of GDNF indicating high activity in dopamine-regenerating processes.

INTERPRETATION

In this preliminary study we demonstrated that radiosurgical lesioning with the Gamma Knife into the striatum of hemi-parkinsonian animals resulted in significant behavioral improvement of signs of parkinsonism. Since GDNF expression is tightly linked to the dopaminergic system, we conclude that focused radiation is potentially capable of inducing regeneration of dopaminergic pathways in the adult CNS. Further studies with dose deescalation and molecular biological characterization of the regeneration cascades are necessary to gain access to potential clinical value of our observations.

MR imaging of pituitary adenomas after gamma knife stereotactic radiosurgery

OBJECTIVE

The purpose of this study was to evaluate the response of pituitary adenomas to radiosurgery as manifested by changes in size and appearance on serial MR imaging.

MATERIALS AND METHODS

Over a mean follow-up period of 36 months, changes in 44 pituitary adenomas were assessed on 147 enhanced MR imaging studies. Prior surgery had been performed in 36 tumors (82%).

RESULTS

At the time of radiosurgery, mean tumor volume was 5.9 +/- 0.8 cm(3) (mean diameter, 2.2 cm). The mean reduction in volume at last follow-up was 41% (+/- 5%, p < 0.001), and a decrease in tumor volume of 25-100% was observed in 34 tumors (77%). Mean reduction in tumor volume at 6 months after radiosurgery was 9% (p = 0.095); at 1 year, 24% (p < 0.001); at 2 years, 34% (p < 0.001); at 3 years, 41% (p < 0.001); and at 4 years, 50% (p = 0.008). Six months after radiosurgery a slight and transient increase in size was observed in 21% of tumors. During follow-up, neither decreased contrast enhancement nor cyst development was associated with changes in tumor volume.

CONCLUSION

Tumor control was observed for most pituitary adenomas after radiosurgery and occurred gradually over a period of several years. A small increase in tumor size might be observed in the first 6 months after radiosurgery. In most cases, reductions in tumor size were not accompanied by a change in contrast enhancement or cyst formation.

Gamma knife surgery for treatment of central neurocytomas. Report of four cases

The authors investigated the use of gamma knife surgery (GKS) in the treatment of central neurocytoma, a usually benign primary brain tumor of the lateral and third ventricles. Four patients with subtotally resected or recurrent central neurocytomas were retrospectively studied. The prescription isodose was 9 to 13 Gy to the 30 to 50% peripheral isodose line. Pre- and postoperative magnetic resonance (MR) images were compared to determine the volume reduction following GKS. Follow-up review included annual MR imaging and clinical evaluation by a neurosurgeon. Follow-up periods ranged from 12 to 99 months. Marked reduction in tumor size was seen in all four patients; the decrease in tumor volume for each was 48%, 72%, 81%, and 77%, respectively, at the last follow-up review. None of the four patients required additional treatment and none experienced a decline in neurological function during the follow-up period. No complications have been noted in any of these patients to date. Even though there have been few observations and follow-up time has been limited, because of the consistency of the response and the lack of observed side effects, GKS may be the treatment of choice for subtotally resected and recurrent central neurocytomas.

Gamma knife radiosurgery for pituitary tumours

Stereotactic radiosurgery with the gamma knife delivers focused radiation from a cobalt-60 source in a single session to a pituitary tumour with minimal radiation to the adjacent normal brain tissue. Currently, gamma knife radiosurgery is predominantly used to treat failed pituitary surgery, although it has a role as a primary treatment for patients unwilling or unsuitable, for medical reasons, to undergo trans-sphenoidal surgery. The major risk from gamma knife radiosurgery is radiation damage to the visual pathways, but this can be avoided by limiting the radiation dose to the optic chiasm to under 10 Gy. In contrast, the neuronal and vascular structures running in the cavernous sinus are much less radiosensitive, allowing an ablative dose to be administered to tumours showing lateral invasion and impinging on cranial nerves III, IV, V and VI. Gamma knife radiosurgery appears to produce remission in secretory tumours faster than fractionated radiotherapy. Furthermore, the potential long-term risk of developing a second extra-pituitary brain tumour, as well as the neuropsychiatric effects associated with conventional radiation administration, seems less likely to occur with this form of treatment.

Role of gamma knife radiosurgery in acromegaly

Stereotactic radiosurgery with the Gamma Knife allows the delivery of focused radiation in a single session from a Cobalt-60 source to a pituitary tumor with little radiation to surrounding normal brain tissue. At this time the major role for Gamma Knife radiosurgery in acromegaly is for the treatment of failed pituitary surgery although it may also by used as primary treatment for patients unwilling or unsuitable, for medical reasons, to undergo transsphenoidal surgery. The major risk from Gamma Knife radiosurgery appears to be radiation damage to the visual pathways, but this can be obviated by limiting the radiation dose to the optic chiasm under 10 Gy. In contrast, the neuronal and vascular structures running in the cavernous sinus are much less radiosensitive allowing an ablative dose to be administered to tumors showing lateral invasion and impinging on cranial nerves III, IV, V and VI. Gamma Knife radiosurgery appears to produce effects in GH secreting tumors faster than with fractionated radiotherapy without the potential long-term risk of developing a second extrapituitary brain tumor as well as the neuropsychiatric effects associated with conventional radiation administration.

Myocardial high-energy phosphate levels in cardiomyopathic turkeys

A congestive cardiomyopathy (CCM) model occurs in inbred broad-breasted turkeys and is manifested by reduced hatchability and a high mortality within a week of hatching. In the survivors, cardiac dilation begins by 3-4 weeks of age and further mortality occurs from chronic congestive heart failure. The mechanisms behind these changes is unknown, and, therefore, we investigated what role, if any, myocardial energy metabolism might play in these events. Ventricular myocardial samples were obtained for analysis of adenine nucleotides (ATP, ADP, AMP) and creatine phosphate (CP) in control and CCM turkeys, 1-31 days old. The adenine nucleotide energy charge (EC) was calculated using the formula EC = ATP + 1/2ADP/(ATP + ADP + AMP). We found the myocardial ATP levels and EC in CCM hearts at 1-2 days were reduced. In control turkeys, no significant age-related differences were found in myocardial high-energy phosphate compounds or in the EC. This depression in the energy metabolism of CCM turkeys may also be reflected in their poor hatchability. By 6-10 days, however, ATP levels had recovered and remained normal despite the onset of cardiac dilation and failure at 3-4 weeks of age in CCM turkeys. Because CP levels in control and CCM turkey hearts were similar in all age groups, significant ischemia did not appear to be present after hatching in CCM turkeys. Our results suggest, therefore, that an insult probably prior to hatching produced depressed myocardial energy levels in CCM turkeys and led to reduced hatchability. This early insult appears to be significant, in that late cardiac dysfunction resulted despite the recovery of myocardial ATP levels.

Contrasting effects of spontaneous and induced cardiomyopathy on the nucleoproteins of turkey hearts

The possible involvement of nuclear proteins in the pathogenesis of cardiomyopathy was studied in a spontaneously occurring and a furazolidone-induced model of turkey cardiomyopathy. Both models are characterised by cardiac hypertrophy and dilatation, systemic hypotension and depressed contractility. The protein composition of myocardial nuclei was compared in normal (n = 9) and cardiomyopathic (spontaneous n = 6, furazolidone-induced n = 21) turkeys. Cardiac nuclei from spontaneously myopathic animals had a higher histone content (1.827 +/- 0.058 (mean +/- SD) mg . mg DNA-1 vs 1.688 +/- 0.187 in controls, P less than 0.05) and histone/nonhistone protein ratio (1.122 +/- 0.020 vs 0.882 +/- 0.128 in controls, P less than 0.01). Nuclear protein phosphorylation was lower in spontaneously cardiomyopathic turkeys primarily because of decreased nonhistone protein phosphorylation (5.100 +/- 0.759 pmol 32 P . mg prot-1 .15 min-1 vs 8.456 +/- 0.886 in controls, P less than 0.01). In contrast, furazolidone-induced cardiomyopathy of similar severity to the spontaneously occurring model was not associated with changes in nucleoprotein composition or degree of phosphorylation. These results indicate that development of spontaneous cardiomyopathy in turkeys may be related to the composition and function of nuclear nonhistone proteins. These changes are not secondary to the cardiac hypertrophy/dilatation accompanying the myopathic process.

Pulmonary atresia with left ventricular-right atrial communication: basis for circular shunt

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