Chitti R. Moorthy

Optic nerve sheath meningiomas: visual improvement after stereotactic radiotherapy.

OBJECTIVE The management of primary optic nerve sheath meningioma (ONSM) is controversial. Surgery often results in postoperative blindness in the affected eye and thus has been abandoned as a treatment option for most patients. When these tumors are left untreated, however, progressive visual impairment ensues, which also leads to blindness. Recently, radiation therapy has gained wider acceptance in the treatment of these lesions. Experience with stereotactic radiotherapy (SRT) in the treatment of ONSMs is limited because of the rare incidence of this tumor. We present a series of patients with ONSM who were treated with SRT. METHODS Five patients (three women, two men), ranging in age from 40 to 73 years, presented with progressive visual loss with decreased visual field, visual acuity, and color vision affecting six eyes (one patient had tumor involving both optic nerves). One patient also presented with proptosis and diplopia. Five eyes had functional residual vision (range, 20/20 to 20/40), and one eye was completely blind. All five patients were diagnosed clinically and radiographically to have an ONSM. Three were intraorbital, one was intracanalicular as well as intraorbital, and one was a left ONSM extending through the optic foramen into the intracranial space and involving the right optic nerve. The five functional eyes were treated with SRT by use of 1.8-Gy fractions to a cumulative dose of 45 to 54 Gy. RESULTS Follow-up ranged from 1 to 7 years, and serial magnetic resonance imaging revealed no changes in the size of the tumor in all five patients. Four patients experienced dramatic improvement in visual acuity, visual field, and color vision within 3 months after SRT. One patient remained stable without evidence of visual deterioration or disease progression. None had radiation-induced optic neuropathy. CONCLUSION SRT may be a viable option for treatment of primary ONSM in patients with documented progressive visual deterioration, and it may be effective in improving or stabilizing remaining functional vision.

Stereotactic body radiation therapy in hepatocellular carcinoma and cirrhosis: evaluation of radiological and pathological response.

Loco‐regional therapies for cirrhotic patients with hepatocellular carcinoma (HCC) who are awaiting liver transplantation (OLT) attempt to prevent tumor progression. However, there is limited data regarding the efficacy of stereotactic body radiation therapy (SBRT) as loco‐regional treatment.

X-irradiation of the contusion site improves locomotor and histological outcomes in spinal cord-injured rats

We have determined whether X-irradiation of the injury site can oppose tissue loss and improve recovery of locomotor function following contusion injury of the spinal cord. Contusion injury was produced in rats at the level of T10 with a weight drop device. Localized X-irradiation (20 Gy) of the injury site was performed at 20 min and 1, 2, 4, 7, and 17 days postinjury. Locomotor recovery was then determined with the 21-point Basso, Beattie, and Bresnahan (BBB) scale. X-irradiation enhanced recovery of locomotor function during a subsequent 6-week observation period when administered 20 min and 1 or 2 days following contusion injury (final BBB score approximately 7-8). X-irradiation at 4-17 days postinjury did not significantly affect final locomotor scores compared with unirradiated rats (final BBB score approximately 2), in marked contrast to previous studies where X-irradiation applied only at 17-18 days benefitted transection injury. The extent of recovery was directly related to measurements of sparing of spinal cord tissue at the contusion center. Because the treatment time window occurred earlier in contusion than reported for transection injury, the results suggest that contusion injury rapidly initiates underlying radiation-sensitive processes that occur only following a delay of several weeks after transection injury. Further optimization of X-ray treatment may lead to a useful therapeutic modality for use in spinal cord contusion injury.

Safety of multiple stereotactic radiosurgery treatments for multiple brain lesions

AbstractBackground: Stereotactic radiosurgery (SRS) is a widely used therapy for multiple brain lesions, and studies have clearly established the safety and efficacy of single-dose SRS. However, as patient survival has increased, the recurrence of tumors and the development of metastases to new sites within the brain have made it desirable to repeat treatments over time. The cumulative toxicity of multi-isocenter, multiple treatments has not been well defined. We have retrospectively studied 10 patients who received multiple SRS treatments for multiple brain lesions to assess the cumulative toxicity of these treatments. Methods: In a retrospective review of all patients treated with SRS using the X-knife (Radionics, Burlington, MA) at Westchester Medical Center/New York Medical College between December 1995 and December 2000, 10 patients were identified who received at least two treatments to at least 3 isocenters and had a minimum follow-up period of 6 months. Image fusion technique was used to determine cumulative doses to targeted lesions, whole brain and critical brain structures. Toxicities and complications were identified by chart and radiological review. Results: The average of the maximum doses (cGy) to a point within the whole brain was 2402 (range 1617–3953); to the brainstem, 1059 (range 48–4126); to the right optic nerve, 223 (range 14–1012); to the left optic nerve, 159 (range 17–475); and to the optic chiasm, 219 (range 15–909). There were no focal neurological toxicities, including visual disturbances, cranial nerve palsies, or ataxia in any of the 10 patients. There were also no global toxicities, including cognitive decline or secondary tumors. Only one patient developed seizures that were difficult to control in association with radiation necrosis. Conclusions: Multiple SRS treatments at the cumulative doses used in our study are a safe therapy for patients with multiple brain lesions.

STEREOTACTIC RADIOSURGERY IMPROVES LOCOMOTOR RECOVERY AFTER SPINAL CORD INJURY IN RATS

OBJECTIVECurrently, because of the precision of stereotactic radiosurgery, radiation can now be delivered by techniques that shape the radiation beam to the tissue target for a variety of clinical applications. This avoids unnecessary and potentially damaging irradiation of surrounding tissues inherent in conventional irradiation, so that irradiation of the minimum volume of tissue necessary for optimal therapeutic benefit can be achieved. Although conventional x-irradiation has been shown to improve recovery from spinal cord injury in animals, the efficacy of targeted irradiation of the injured spinal cord has not been demonstrated previously. The purpose of these studies was to determine whether stereotactic x-irradiation of the injured spinal cord can enhance locomotor function and spare spinal cord tissue after contusion injury in a standard experimental model of spinal cord injury. METHODSContusion injury was produced in rats at the level of T10 with a weight-drop device, and doses of x-irradiation were delivered 2 hours after injury via a Novalis, 6-MeV linear accelerator shaped beam radiosurgery system (BrainLAB USA, Westchester, IL) in 4 sequential fractions, with beam angles 60 to 70 degrees apart, at a rate of 6.4 Gy/minute. The target volume was a 4 × 15-mm cylinder along the axis of the spinal cord, with the isocenter positioned at the contusion epicenter. Locomotor function was determined for 6 weeks after injury with the 21-point Basso, Beattie, and Bresnahan (BBB) locomotor scale and tissue sparing in histological sections of the spinal cord. RESULTSLocomotor function recovered progressively during the 6-week postinjury observation period. BBB scores were significantly greater in the 10-Gy x-irradiated group compared with controls (9.4 versus 7.3; P < 0.05), indicating hind limb weight support or dorsal stepping in contrast to hind limb joint mobility without weight bearing. Doses in the range of 2 to 10 Gy increased BBB scores progressively, whereas greater doses of 15 to 25 Gy were associated with lower BBB scores. The extent of locomotor recovery after treatment with x-irradiation correlated with measurements of spared spinal cord tissue at the contusion epicenter. CONCLUSIONThese results suggest a beneficial role for stereotactic radiosurgery in a rat model of acute spinal cord contusion injury and raise hopes for human treatment strategies. Additional animal studies are needed to further define potential benefits.

Interstitial Brachytherapy in Head and Neck Tumors

Brachytherapy presently, in spite of the extensive utilization of external megavoltage radiation, plays a significant role in the management of head and neck cancer. The early techniques of interstitial brachytherapy using radium needles were developed in the early 1920s in Paris by Regaud, Lacassagne, and Coutard (see del Regato 1986, 1987). Paterson and parker in 1934 developed the dosage system known as the Manchester, which placed interstitial brachytherapy on a more rational basis. Paterson recognized very early on that the dose that can be safely delivered by brachytherapy varied with the volume implanted and that the smaller the volume, the greater the tolerance. This marked dependency of the tissue tolerance dose on the size of the irradiated volume is the key to understanding the value of interstitial brachytherapy in head and neck cancer. The other advantage of brachytherapy, and we refer to the precise localization of the radiation effect, is more evident in the head and neck because of easy tumor accessibility and visibility. The role of brachytherapy was strengthened by the introduction of afterloading techniques and artificial radionuclides, especially iridium 192, in the mid 1950s by Henschke et al. (1963) in New York. Recent developments in computer technology and the imaging revolution have created the tools to describe the patient’s anatomy and to calculate and display dose distributions (Hilaris et al. 1987a). Thus, interstitial brachytherapy continues to be an indispensable adjunct to the management of many head and neck cancers.