Gamma knife radiosurgery of epidermoid tumors: an analysis of treatment results of eight patients.

BACKGROUND: Epidermoid tumors (ETs) of the central nervous system (CNS) are rare tumors that typically occur in the 4th decade. They typically grow around vital neurovascular structures which makes surgical treatment difficult. The objective of this paper is to report on the effectiveness and safety in the management of epidermoid tumors with gamma knife surgery (GKS). MATERIALS AND METHODS: This is a retrospective study of the medical records of 8 patients treated with GKS for epidermoid tumors between July 2010 to June 2019. The median prescription dose was 11 Gy, ranging from 10 to 12 Gy, 5 patients received the total dose target to the 50% line and 3 to the 55% isodose line. The mean tumor volume was 12.4 cc ranging from 4.4 to 24.8cc. The median follow-up time was 33.7 months and ranged from 0.9 to 58.8 months. At follow-up, patients were evaluated for neurological signs and symptoms and radiographic evidence of progression of disease. Two patients were treated after failure of linac stereotactic radiosurgery. One patient underwent stereotactic radiosurgery prior to GKS, and the other had failed surgical resection prior to GKS. RESULTS: The median age was 33 years old. There were two males and six females. The most common presenting manifestation was headaches followed by vision and hearing problems. Symptoms were resolved in all cases, except for one who had partial control of trigeminal neuralgia. All patients were locally controlled by imaging and neurological examination at first follow-up. CONCLUSION: Gamma knife surgery is a safe and effective alternative treatment in patients with CNS epidermoid tumors and should be included in the initial recommendation.

Radiosurgery for brain metastases from ovarian cancer: an analysis of 25 years' experience with Gamma Knife treatment.

PURPOSE: We present our results in the treatment of brain metastases (BM) from ovarian cancer using Gamma Knife Radiosurgery (GKRS) over the last 25 years in a single institution. BACKGROUND: Gamma Knife Radiosurgery has become increasingly important in the management of brain metastases from ovarian cancer due to improving results from systemic disease and the need for better outcomes. MATERIAL AND METHODS: The medical records of 9 patients with brain metastases from ovarian cancer treated with GKRS between 1993 and 2018 were reviewed. Median age at first treatment was 57 years (range 39-76). Forty-two brain metastases were treated with 16 procedures. Median tumor volume was 1.8cc ranging from 0.2 to 30.3cc (there were five patients with a tumor volume exceeding 10cc). Median prescription dose was 16 Gy. RESULTS: Using Kaplan Meier estimates, the median OS after diagnosis was 48.1 months and the median OS after GKRS was 10.6 months (ranging from 2.5 to 81 months). The Kaplan Meier survival rates were 31.3%, and 6.5% at 2 and 5 years after GKRS, respectively. Treatment procedure was well tolerated and no patient presented with acute or chronic toxicity. Two of 9 patients had a tumor requiring retreatment (local control of 95% 40/42). Two out of the 7 patients evaluated for cause of death expired due to progression of brain metastases and the remaining ones died of systemic disease with brain control. CONCLUSIONS: GKRS for BM from ovarian cancer is a safe and effective modality. Our findings are in agreement with the recent literature indicating that women with brain metastases from ovarian cancer will benefit with radiosurgery and may achieve long term survival with brain control.

First Case of Debilitating Lower Back Pain Induced by Severe Inflammation of Lumbar Joints, Healed by Intravenous Infusions of Purified Amniotic Fluid.

We report the first case of debilitating lower back pain induced by spondylitis with end plate inflammation of the lumbar spine, treated successfully by bi-weekly intravenous injections of a sterile fraction (1ml) from human purified amniotic fluid (ViX001) obtained from thoroughly screened volunteers at the time of planned c-section at the term of normal pregnancies. Our product ViX001 was generated through a proprietary process and kept in frozen one milliliter (1 ml) cryvials (protein content was ~1mg/ml) and thawed just prior to injections. Pain improvement was recorded weekly, and inflammation suppression was confirmed by monthly MRIs of the lumbar spine. While our findings need to be reproduced with a larger cohort of patients, it is instructive that ViX001 resolved pain and inflammation for a patient with severe lower back pain, the most common form of pain reported by U.S. adults.

The Value of Statistics and Evidence-Based Medicine in the Care of Neurosurgical Patients.

Science and the art of surgery should be anchored on evidence-based medicine. There is no room in the discipline of neurosurgery for "personal anecdotes/experience," and the concept of "hero worship." The construction of evidence-based medicine guidelines is essential in our continued improvement of care for neurosurgical patients.

Second Gamma Knife Treatment for Trigeminal Neuralgia: Anterior Target Spacing and 25 Gy as the Second Dose.

Objective Gamma Knife® radiosurgery (GKRS) has been demonstrated to be a well-known approach for treating patients with medical refractory trigeminal neuralgia (TN). Herein, the authors review the outcomes of pain among a large cohort of patients who had undergone a second GKRS delivered at a significantly reduced dose. Methods The authors conducted a prospective analysis of patients who have undergone two GKRS procedures between the years 2012 to 2021 at one institution. Baseline characteristics, radiosurgical dosimetry and technique, pain outcomes, and adverse effects were reviewed. Pain outcomes were measured with the Barrow Neurological Institute (BNI) pain intensity scale, which included the best BNI attained after the last treatment and recurrence. Results A total of 202 patients were identified, including 55 males and 147 females. Pain recurrence was reported in all patients prior to the second GKRS treatment (median = 4 months). Pain recurrence in the preceding Japan Neuroscience Society (JNS) 2021 study was also reported in all patients after each GKRS with a median value of 20 months between the second and third procedures. Complete to partial pain relief (BNI ≤ III) was achieved in 80% of patients after the second treatment. Over a median of 12 months of follow-up, 60% of patients maintained complete to partial pain relief compared to 77% of patients over the course of three treatments. In the present study, one patient developed facial spasms while 10 patients experienced persistent facial tingling. Subjective mild numbness was also found to be present in 16% of patients, with only 2% being bothersome, as compared to the JNS study, where subjective mild numbness was found to be present in 14%, with only 14.3% being bothersome. Among the 202 patients, 74 (37%) patients had undergone subsequent additional procedures such as a third GKRS, microvascular decompression (MVD), or other percutaneous procedures. Conclusion The authors describe the largest study to date of patients undergoing a second GKRS treatment for type 1 medical refractory trigeminal neuralgia. A reduced dose of radiation for a second treatment may produce outcomes similar to those of three consecutive treatments in regard to limiting recurrence and adverse effects.

Long-Term Results of Gamma Knife Radiosurgery for Glomus Tumors: An Analysis of 32 Patients.

Background Glomus jugulare tumors are rare slow-growing hypervascular tumors that arise from the paraganglia of the chemoreceptor system within the jugulare foramen of the temporal lobe. The historical standard treatment has been surgical resection, but because of their high vascularity and involvement with cranial nerves (CNs), Gamma Knife radiosurgery (GKRS) has been advocated as an alternative. The goal of this study is to update and report long-term results of GKRS to achieve local control and symptomatic improvement and to reduce morbidity and mortality when treating glomus jugulare tumors. Materials and Methods This study retrospectively collected and reviewed clinical and radiographic data of 32 patients with glomus jugulare tumors treated with GKRS at the Miami Neuroscience Center, South Miami, FL, from 1995 to 2019. For the 32 patients, the mean volume treated was 13.9 cc (0.23 to 40.0 cc), with an average of 8.6 isocenters. The median prescription dose was 12.84 Gy ± 2.07 Gy (range: 10-20 Gy). Follow-up data were available for 29 out of 32 patients, with a median clinical follow-up time of 37.3 months (range: 4.3-169.1 months). At follow-up, patients were evaluated for neurological signs and symptoms and radiographic evidence of progression of disease. Results The median age of the cohort treated with GKRS was 60 years (range: 14-83 years). There were three males and 27 females. Presenting symptomatology was available for 30 out of 32 patients. The most common presenting symptom was hearing loss (21/30) and the most common CN deficit was in CN VIII (19/30). Out of 29 of the patients followed up, 28 patients had improvement (20/29) or resolution (8/29) of symptoms. At the most recent evaluation or contact, patients were without symptomatic progression of CN deficits. Radiographic tumor control was achieved in 28 out of 29 patients. One patient had a recurrence seven years after GKRS, which was treated with surgery. There were no complications, radionecrosis, or mortality reported from GKRS. Conclusion These data confirm that GKRS is a reasonable upfront treatment option for glomus jugulare tumors. GKRS should be considered more frequently given its excellent long-term local control with low morbidity and risk of complications.

Gamma knife stereotactic radiosurgery as an effective tool in primary CNS lymphoma: Evaluation of stereotactic radiosurgery and methotrexate treatment in a prospective and observational clinical research study.

OBJECTIVE: The purpose of this study was to compare the progression of Primary Central Nervous System Lymphoma (PCNSL) in patients treated with methotrexate (MTX) versus those treated with a combination of Stereotactic Radiosurgery (SRS) and MTX. Progression was measured via brain lesion count and tumor volume. METHODS: This observational and prospective cohort study evaluated the outcome of SRS treatment of PCNSL in one hundred twenty-eight subjects. We analyzed baseline, prospective, and retrospective data of patients enrolled in the brain tumor registry between June 2010 and August 2017. Seventy-three patients were treated exclusively with MTX while the remaining fifty-five patients received a combination of SRS and MTX. Strict inclusion and exclusion criteria were established. RESULTS: Mean survival rate for patients receiving combined SRS and MTX treatment was significantly higher (52.6 months) compared to the MTX group (19.8 months); p = 0.0029. At the 36 months follow-up, patients treated with SRS and MTX also had a lower rate of tumor progression (32.7 %) than the MTX group (95.9 %); p = 0.00192. Local tumor control was achieved in all patients treated with SRS. No clinical toxicity was observed in this group. CONCLUSIONS: Clinical results obtained from this observational study highlight the potential effectiveness of SRS in the treatment of PCNSL. Although treatment outcomes have improved in the past years, additional evidence in the clinical design of randomized trials is needed to evaluate the strength of this treatment in specific situations.

Highly Active Antiretroviral Therapy and Gamma Knife Radiosurgery for the Treatment of AIDS-Related Primary Central Nervous System Lymphoma.

BACKGROUND: The criterion standard for the treatment of newly diagnosed primary central nervous system lymphoma (PCNSL) remains high-dose chemotherapy in conjunction with palliative whole-brain radiotherapy; however, there may be a role for novel combined approaches in immunocompromised patients. CASE DESCRIPTION: A 66-year-old man presented with acute cephalalgia, disorientation, and lethargy. His condition was evaluated in the emergency department, and he was admitted with probable hydrocephalus. Magnetic resonance imaging (MRI) of the brain revealed multiple nonspecific brain lesions, predominantly involving the right temporal lobe, which on biopsy led to a diagnosis of PCNSL. Subsequent laboratory studies demonstrated active human immunodeficiency virus (HIV) infection, with a CD4 count of 21 cells/µL and an HIV viral load (VL) of >400,000 copies/mL. The patient was eventually given highly active antiretroviral therapy (HAART). He declined palliative whole-brain radiotherapy but was amenable to gamma knife radiosurgery (GKRS) for treatment of the right temporal brain lesions. Three months later, the patient's neurologic symptoms had improved; similarly, his CD4 count increased to 176 cells/mL, and his HIV viral load was <90 copies/mL. By the 12-month follow-up visit, the patient was asymptomatic, and at 36 months, MRI of the brain demonstrated total remission without new brain lesions. CONCLUSIONS: The criterion standard for treatment of newly diagnosed PCNSL remains high-dose chemotherapy in conjunction with palliative whole-brain radiotherapy; however, there may be a role for novel combined approaches using chemotherapy, HAART, and GKRS to have a positive impact on survival rates of PCNSL related to AIDS.

Tyrosyl-DNA Phosphodiesterase 1 and Topoisomerase I Activities as Predictive Indicators for Glioblastoma Susceptibility to Genotoxic Agents.

Glioblastoma (GBM) patients have an estimated survival of ~15 months with treatment, and the standard of care only modestly enhances patient survival. Identifying biomarkers representing vulnerabilities may allow for the selection of efficacious chemotherapy options to address personalized variations in GBM tumors. Irinotecan targets topoisomerase I (TOP1) by forming a ternary DNA-TOP1 cleavage complex (TOP1cc), inducing apoptosis. Tyrosyl-DNA phosphodiesterase 1 (TDP1) is a crucial repair enzyme that may reduce the effectiveness of irinotecan. We treated GBM cell lines with increasing concentrations of irinotecan and compared the IC50 values. We found that the TDP1/TOP1 activity ratio had the strongest correlation (Pearson correlation coefficient R = 0.972, based on the average from three sets of experiments) with IC50 values following irinotecan treatment. Increasing the TDP1/TOP1 activity ratio by the ectopic expression of wild-type TDP1 increased in irinotecan IC50, while the expression of the TDP1 catalytic-null mutant did not alter the susceptibility to irinotecan. The TDP1/TOP1 activity ratio may be a new predictive indicator for GBM vulnerability to irinotecan, allowing for the selection of individual patients for irinotecan treatment based on risk-benefit. Moreover, TDP1 inhibitors may be a novel combination treatment with irinotecan to improve GBM patient responsiveness to genotoxic chemotherapies.

A case report and technical tip of chronic subdural hematoma treated by the placement of a subdural peritoneal shunt.

BACKGROUND: Chronic subdural hematomas (CSDH) tend to occur most commonly in the elderly population, usually resulting from minor or insignificant head trauma. The pathophysiology behind CSDH is often directly associated with cerebral atrophy, and other causes of cerebral atrophy such as alcoholism or dementia. Other predisposing factors include diabetes, coagulopathy, use of anticoagulants (including aspirin), seizure disorders, and CSF shunts. Considerable evidence supporting the use of external drainage after evacuation of primary CSDH is readily available in the literature. CASE REPORT: We report the case of a 72 year-old male with a history of recurrent left subdural hematoma presenting to the neurosurgical clinic with a two-day history of personality changes, difficulty speaking, urinary incontinence, and headaches. Burr hole evacuation was performed with the placement of a subdural peritoneal shunt. At the one-month follow-up appointment, the patient had complete resolution of symptoms and CT scan showed no new recurrence of the subdural hematoma. CONCLUSIONS: Although several treatment options are available for the management of CSDH, recurrence of hematoma is a major and very common complication that may result in re-injury due to mass effect caused by chronic hematoma. However, placement of subdural peritoneal shunt for the treatment of CSDH can reduce the recurrence rate of CSDH and therefore, reduce the risk of brain re-injury.

Comparison of Percutaneous Retrogasserian Balloon Compression and Gamma Knife Radiosurgery for the Treatment of Trigeminal Neuralgia in Multiple Sclerosis.

OBJECTIVE: We compared and evaluated percutaneous retrogasserian balloon compression (PBC) and Gamma Knife radiosurgery (GKRS) for treatment of trigeminal neuralgia (TN) in patients with multiple sclerosis (MS). METHODS: In this single-center, retrospective comparative study, 202 patients with MS and concomitant TN were evaluated. A minimum follow-up of 24 months was required. Patients with a history of microvascular decompression or previous intervention were excluded. Between February 2009 and December 2013, 78 PBC procedures and 124 first-dosage GKRS procedures were performed. PBC procedures were successfully completed in all cases. The 2 groups were compared with regard to initial effect, duration of effect, and complications including type and severity. RESULTS: Immediate pain relief occurred in 87% of patients treated with PBC and in 23% of patients treated with GKRS. Kaplan-Meier plots for the 2 treatment modalities were similar. The 50% recurrence rate was at 12 months for the PBC group and 18 months for the GKRS group. Complication (excluding numbness) rates were 3% for GKRS and 21% for PBC. The difference was statistically significant (χ2 test, P = 0.03). CONCLUSIONS: PBC and GKRS are effective techniques for treatment of TN in patients with MS. Fewer complications and superior long-term relief were associated with GKRS. We consider GKRS as the first option for the treatment of TN in patients with MS, reserving PBC for patients with acute, intractable pain.

Primary Central Nervous System Lymphoma (PCNSL): Analysis of Treatment by Gamma Knife Radiosurgery and Chemotherapy in a Prospective, Observational Study.

BACKGROUND: Primary central nervous system lymphoma (PCNSL) is a rare cancer accounting for less than 3% of primary brain and central nervous system (CNS) tumors. Tissues involved include the brain parenchyma, leptomeninges, eyes, and spinal cord. High-dose methotrexate (MTX) is the gold standard for newly diagnosed PCNSL. However, Gamma Knife radiosurgery (GKRS) may be efficacious as a co-adjuvant treatment. The purpose of this prospective observational cohort study is to determine the effectiveness of MTX in combination with GKRS in the treatment of PCNSL. METHODS: This is a prospective, observational cohort study evaluating the treatment of histologically confirmed PCNSL with MTX as a single agent in a dose of 8 g/m2 (control) and treatment with MTX, plus GKRS. Strict inclusion and exclusion criteria were employed. Primary outcomes were measured by survival rate. Secondary outcomes were assessed by the tumor's responsiveness to treatment and reduction in size as noted on imaging. RESULTS: Between January 2007 and January 2012, 128 charts were evaluated. Included in this evaluation were 73 chemotherapy (control) and 55 chemotherapy, plus GKRS, patients (variable). The follow-up period was 24 to 49 months (mean: 36.9 months). There were no statistically significant differences in patient demographics or histology diagnosis. Patients were treated with GK doses ranging from 11 Gy to 16 Gy (median: 11 Gy). The median survival rate from initial diagnosis was 26.8 months in the chemotherapy group and 47.6 in the chemotherapy, plus GKRS, group (p-value: 0.0034). All lesions showed a complete response after GKRS when evaluated using magnetic resonance imaging after three to eight weeks (mean range: 6.3 weeks). CONCLUSIONS: The use of GKRS is non-invasive, safe, and shows rapid success, improving the prognosis of the patient. This noninvasive treatment modality should be considered as an option for patients with PCNSL. In our study, GKRS as a co-adjuvant therapy to high-dose methotrexate was statistically significant for greater tumor control, enhanced overall survival period, and a lesser number of complications.

Is Subdural Peritoneal Shunt Placement an Effective Tool for the Management of Recurrent/Chronic Subdural Hematoma?

UNLABELLED: OBJECTIVE : To describe a surgical technique and to report using a retrospective study the efficacy of peritoneal shunts for the treatment of recurrent/chronic subdural hematoma (CSDH). We describe the considerations, complications, and outcomes related to this technique. METHODS : In a retrospective cohort study, 125 charts with a diagnosis of subacute/chronic subdural hematoma were assigned for evaluation. Of the charts reviewed, 18 charts were found from subjects with a diagnosis of recurrent sub-acute or chronic subdural hematoma. All patients had undergone initial surgical treatment of their condition followed by peritoneal shunt placement to help alleviate intracranial pressure. Factors including the age, size of subdural hematoma, number of previous events, BMI, complications, survival, and clinical course were analyzed. RESULTS : After subdural peritoneal shunt placement all patients had full neurological recovery with no complaints of headaches, lethargy, weakness, confusion or seizures. None of the cases had new subdural hematoma episodes after placement for a minimum of a two-year period (mean 26.1 months) (range 24.3-48.6 months). No postoperative complications were reported. The rates of postoperative hemorrhage, infection, distal catheter revision, and perioperative seizures was found to be zero percent. Shunt drainage was successful in all cases, draining 85% of the blood in the first 48 hours. There was no significant relationship between complications and the use of anticoagulants four weeks after surgery. CONCLUSIONS: Peritoneal shunts, though rarely used, are a viable option in the treatment of sub-acute/chronic subdural hematomas. When pursuing this treatment, this technique is recommended to mitigate the risks of repeat surgical intervention and lessen perioperative time in high-risk patients.

Pineal tumors: analysis of treatment results in 20 patients.

OBJECT: The authors evaluate their results when using gamma knife surgery (GKS) in the management of patients with tumors in the pineal region. METHODS: This is a retrospective clinical evaluation of 20 patients with primary tumors of the pineal region treated with GKS from November 1994 through August 2003. There were 13 germ cell tumors, two pineoblastomas, two low-grade gliomas, one primitive neuroectodermal tumor, one teratoma, and one pineocytoma. There were 10 male and 10 female patients. Their median age was 15.5 years (range 5-71 years). The median margin dose was 11 Gy (range 8-20 Gy). The median target volume was 3.1 cm3 (range 0.1-49.9 cm3). Five patients received sequential systemic chemotherapy and four underwent adjuvant conventional radiation therapy. Seventeen (85%) of 20 patients are alive with a median survival of 30.4 months (range 0-85.7 months). Two patients required retreatment. Three patients died: one of unrelated causes, one who presented with extensive local disease, and the other of meningeal carcinomatosis with local control of the primary tumor. No complications from GKS were noted. CONCLUSIONS: This initial experience suggests that GKS is a valuable treatment modality for the management of pineal region tumors. This technique offers excellent local tumor control and minimal patient morbidity, allowing for immediate use of systemic chemotherapy and/or conventional radiation if indicated.

Radiosurgery as palliation for brain metastases: a retrospective review of 72 patients harboring multiple lesions at presentation.

OBJECT: The purpose of this study was to determine the outcome of palliative gamma knife radiosurgery (GKS) in a group of poor-risk patients with multiple brain metastases. METHODS: The medical records of 72 patients with multiple brain metastases treated with GKS between October 1993 and November 9, 2001, were reviewed retrospectively. All patients presented with more than 10 lesions. There were 26 men and 46 women. The median age was 60 years (range 24-84 years). There were 39 patients with lung cancer, 18 with breast cancer, nine with metastatic melanomas, two with metastatic renal cell carcinomas, and four with other primary tumors. A total of 147 treatment sessions were required to treat 1304 sites in 72 patients. A mean of 10.4 isocenters per treatment was used. The mean tumor volume was 1.7 cm3. All patients had extracranial disease. The variables included in this study were the patient's Karnofsky Performance Scale score, age, sex, the radiation dose, initial number of lesions, and tumor volume and histopathology. CONCLUSIONS: Radiosurgery can be a powerful tool in the palliative management of advanced metastatic disease even in patients presenting with multiple brain metastases. A median of two outpatient treatments was required, allowing the advanced cancer patient to avoid protracted fractionated radiotherapy and to undergo other therapeutic treatment with an acceptable quality of life.

Role of radiosurgery in craniopharyngiomas: a preliminary report.

PURPOSE: The purpose of this retrospective review is to evaluate our experience using radiosurgery in the management of craniopharyngiomas. MATERIALS AND METHODS: Fourteen patients, 6 males and 8 females, ages ranging from 3 to 44 years of age, were treated with radiosurgery from February 1994 through December 2000 for primary or recurrent craniopharyngioma. There were two adults and 12 children. All patients were treated with the Leksell Gamma units Model U or C. The mean minimum dose was 14 Gy ranging from 11 to 20 Gy and the mean maximum dose was 29 Gy ranging from 24 to 40 Gy. Volume of treatment ranged from 0.1 to 26.5 cm(3). The dose to critical structures was below 8 Gy to the optic chiasm and below 14 Gy to the brain stem. One of the 14 patients had previous conventional radiation therapy. RESULTS: All patients are alive and with out evidence of recurrent disease 6-86 months after treatment. Only two patients required retreatment. CONCLUSIONS: Although craniopharyngioma is a benign tumor, its location makes even advanced microsurgical techniques difficult to perform. Radiosurgery obviates the shortcomings of surgical resection near the hypothalamic-pituitary axis without the morbidity of open surgery.

The use of stereotactic radiosurgery to treat intractable childhood partial epilepsy.

PURPOSE: Although conventional surgery is presently used to treat seizures of temporolimbic and neocortical origin, deep-seated lesions are often associated with morbidity. Stereotactic radiosurgery is a noninvasive procedure that effectively treats patients with vascular malformations and brain tumors, but its efficacy for epileptogenic foci is limited, especially in children. METHODS: Between 1995 and 1999, four candidates who had medically uncontrolled seizures and localized seizure foci were selected for stereotactic radiosurgery, with a mean age of 9.75 years at the time of surgery (range, 4-17 years). Seizure foci were identified on the basis of ictal and interictal video-EEG. Magnetic resonance (MR) images were obtained before and after surgery. Ictal single-photon emission computed tomography (SPECT) was performed by using stabilized hexamethyl-propyleneamine oxime (HMPAO; 300 microcuries/kg) with early injection after electrographic ictal onset. The clinical features of the patients are given. All radiosurgical procedures were performed with the gamma knife unit with the Leksell stereotactic frame, stereotactic MRI imaging, and the Gamma Plan workstation. Seizure outcome was scored according to Engel's classification. RESULTS: Two patients had hypothalamic hamartoma (HH), and two had neocortical epilepsy. At mean follow-up of 39.2 months (range, 26-69 months), two patients were seizure free, one with a HH and one with a suggestive developmental tumor in the insular cortex by MRI findings. The other patient with HH had 90% reduction of seizures. One patient with a widespread seizure focus that involved the motor strip was unimproved. The two patients with HH also exhibited markedly improved neurobehavioral status after surgery. There were no significant complications of radiosurgical therapy. CONCLUSIONS: Our findings suggest that gamma knife surgery is a potentially valuable treatment modality for children with medically intractable epilepsy due to a well-localized seizure focus that is difficult to excise by conventional techniques or for whom they are deemed unsuitable. More widespread application in childhood epilepsy should be investigated in larger series.