Gamma Knife for Functional Diseases

Régis, Jean

doi:10.1007/s13311-014-0276-z

Cited by 27 publications

(22 citation statements)

References 75 publications

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“…6 In these interventions, functional radiosurgery typically consists of a 1-time, high-dose treatment to a predefined, specific neuroanatomical location, involving a single GKRS shot with a 4-mm collimator. 12,14,22 The doses used in functional GKRS typically range from 80 to 180 Gy and therefore are much higher than those used in the treatment of patients with malignant or benign tumors. Although functional GKRS has been reported to have low rates of toxicity in most series, it has, in rare instances, been associated with severe neurological sequelae and even death from radionecrosis.…”

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confidence: 99%

“…Although functional GKRS has been reported to have low rates of toxicity in most series, it has, in rare instances, been associated with severe neurological sequelae and even death from radionecrosis. 6,19,22,27 Given that functional GKRS is used to improve the quality of life of patients with functional disorders, it is of utmost importance to investigate factors that may contribute to treatment-related adverse effects in GKRS.…”

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The impact of cobalt-60 source age on biologically effective dose in high-dose functional Gamma Knife radiosurgery

Kann¹,

Yu²,

Stahl³

et al. 2016

JNS

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OBJECTIVEFunctional Gamma Knife radiosurgery (GKRS) procedures have been increasingly used for treating patients with tremor, trigeminal neuralgia (TN), and refractory obsessive-compulsive disorder. Although its rates of toxicity are low, GKRS has been associated with some, if low, risks for serious sequelae, including hemiparesis and even death. Anecdotal reports have suggested that even with a standardized prescription dose, rates of functional GKRS toxicity increase after replacement of an old cobalt-60 source with a new source. Dose rate changes over the course of the useful lifespan of cobalt-60 are not routinely considered in the study of patients treated with functional GKRS, but these changes may be associated with significant variation in the biologically effective dose (BED) delivered to neural tissue.METHODSThe authors constructed a linear-quadratic model of BED in functional GKRS with a dose-protraction factor to correct for intrafraction DNA-damage repair and used standard single-fraction doses for trigeminal nerve ablation for TN (85 Gy), thalamotomy for tremor (130 Gy), and capsulotomy for obsessive-compulsive disorder (180 Gy). Dose rate and treatment time for functional GKRS involving 4-mm collimators were derived from calibrations in the authors' department and from the cobalt-60 decay rate. Biologically plausible values for the ratio for radiosensitivity to fraction size (α/β) and double-strand break (DSB) DNA repair halftimes (τ) were estimated from published experimental data. The biphasic characteristics of DSB repair in normal tissue were accounted for in deriving an effective τ1 halftime (fast repair) and τ2 halftime (slow repair). A sensitivity analysis was performed with a range of plausible parameter values.RESULTSAfter replacement of the cobalt-60 source, the functional GKRS dose rate rose from 1.48 to 2.99 Gy/min, treatment time fell, and estimated BED increased. Assuming the most biologically plausible parameters, source replacement resulted in an immediate relative BED increase of 11.7% for GKRS-based TN management with 85 Gy, 15.6% for thalamotomy with 130 Gy, and 18.6% for capsulotomy with 180 Gy. Over the course of the 63-month lifespan of the cobalt-60 source, BED decreased annually by 2.2% for TN management, 3.0% for thalamotomy, and 3.5% for capsulotomy.CONCLUSIONSUse of a new cobalt-60 source after replacement of an old source substantially increases the predicted BED for functional GKRS treatments for the same physical dose prescription. Source age, dose rate, and treatment time should be considered in the study of outcomes after high-dose functional GKRS treatments. Animal and clinical studies are needed to determine how this potential change in BED contributes to GKRS toxicity and whether technical adjustments should be made to reduce dose rates or prescription doses with newer cobalt-60 sources.

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confidence: 99%

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confidence: 99%

The impact of cobalt-60 source age on biologically effective dose in high-dose functional Gamma Knife radiosurgery

Kann¹,

Yu²,

Stahl³

et al. 2016

JNS

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“…While gamma knife radiosurgery is well known, its use in functional neurosurgical procedures, including epilepsy, pain, movement disorders, and psychiatry, is increasing, and this is expertly reviewed by Regis [12].…”

Section: Implanted Devices Can Be Targeted Quite Precisely To Affectmentioning

confidence: 99%

Nonpharmacological Therapies for Neurologic Devices

Lozano

Kopell

2014

Neurotherapeutics

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“…Because all HHs causing epilepsy are attached to one of the mammillary bodies, [33][34][35] the risk of memory deficit is common to all the ablative techniques. The fact that no destructive effect is observed in most of the patients after radiosurgery 36,37 may explain why no memory deficits have been found (even with long-term follow-up) after radiosurgery despite the use of a battery of standardized neuropsychological tests exploring intelligence and memory (immediate and delayed verbal and visual memory). 29 In the early 2010s, new stereotactic thermocoagulation methods using magnetic resonance (MR) guidance such as highly focused ultrasound (HIFU) and laser interstitial (LITE) 38 thermocoagulation were introduced to the field of functional neurosurgery and tested for the treatment of HH.…”

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Achieving a cure for hypothalamic hamartomas: a Sisyphean quest?

2017

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Hypothalamic hamartomas (HHs), although rare, has raised much interest due to the uniqueness of their clinical symptoms, the mystery of the subcortical-cortical networks involved in their pathogenesis, and the unparalleled complexity posed by their surgical treatment as a lesion-related epilepsy.Paillas, Roger, and colleagues in 1969 were the first to describe the clinical, radiologic, and histologic presentation of "epileptic" HH 1 and to resect the HH in order to treat the associated epilepsy.1 Since then, concepts of the electroclinical expression of epilepsy observed in association with HHs, and the available therapeutic approaches, have evolved rapidly and dramatically. The development of different surgical approaches, and of the concepts about the role of the HHs in relation to the epilepsy, in this typically drug-resistant condition, 2 has gone through a series of cycles. In 1993, Cascino and colleagues reported evidence of seizure onset involving the temporal (and/or frontal) lobe leading to neocortical resection following the traditional electroclinical mapping scheme of the epileptogenic zone with surgical implantation of intracranial electrodes (without electrode placement into the HH lesion). This strategy led to repeated failures. 3 In 1995, Claudio Munari, using stereoencephalography (SEEG), recorded ictal discharges in the HH, 4 thus demonstrating the role of the HH itself as an intrinsically epileptogenic lesion. Simultaneously in support of this hypothesis came the demonstration of hyperperfusion of the HH with ictal single-photon emission computed tomography (SPECT) by Kuzniecky and colleagues. The concept of an essentially subcortical epilepsy, with the epileptogenic zone (EZ) being centered on the HH itself, paved the way for lesion resection becoming a standard treatment for HHs that were associated with drug-resistant epilepsy. Such a lesional approach tended to require a relatively simple preoperative workup, notably without intracranial recording in the majority of cases. Small series

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Gamma Knife for Functional Diseases

Cited by 27 publications

References 75 publications

The impact of cobalt-60 source age on biologically effective dose in high-dose functional Gamma Knife radiosurgery

The impact of cobalt-60 source age on biologically effective dose in high-dose functional Gamma Knife radiosurgery

Nonpharmacological Therapies for Neurologic Devices

Achieving a cure for hypothalamic hamartomas: a Sisyphean quest?

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