Faculty Bibliography

Stereotactic radiosurgery is used for many neoplastic, vascular, and functional disorders of the nervous system. The expanded use of this technique over the past two decades is based mainly on the spectrum of clinical research performed for these disorders. From case series to randomized trials, the safety and efficacy of radiosurgery is well documented. In this report, we discuss the key indications for radiosurgery and the kinds of research performed in this field.

BACKGROUND: Patients with small-cell lung cancer have a high likelihood of developing brain metastases. Many of these patients will have prophylactic cranial irradiation (PCI) or eventually undergo whole brain radiation therapy (WBRT). Despite these treatments, a large number of these patients will have progression of their intracranial disease and require additional local therapy. Stereotactic radiosurgery (SRS) is an important treatment option for such patients. METHODS: We retrospectively reviewed the charts of 44 patients with brain metastases from small-cell lung cancer treated with gamma knife SRS. Multivariate analysis was used to determine significant prognostic factors influencing survival. RESULTS: The median follow-up from SRS in this patient population was 9 months (1-49 months). The median overall survival (OS) was 9 months after SRS. Karnofsky performance status (KPS) and combined treatment involving WBRT and SRS within 4 weeks were the two factors identified as being significant predictors of increased OS (p = 0.033 and 0.040, respectively). When comparing all patients, patients treated with a combined approach had a median OS of 14 months compared to 6 months if SRS was delivered alone. We also compared the OS times from the first definitive radiation: WBRT, WBRT and SRS if combined therapy was used, and SRS if the patient never received WBRT. The median survival for those groups was 12, 14, and 13 months, respectively, p = 0.19. Seventy percent of patients had follow-up magnetic resonance imaging available for review. Actuarial local control at 6 months and 12 months was 90% and 86%, respectively. Only 1 patient (2.2%) had symptomatic intracranial swelling related to treatment, which responded to a short course of steroids. New brain metastases outside of the treated area developed in 61% of patients at a median time of 7 months; 81% of these patients had received previous WBRT. CONCLUSIONS: Stereotactic radiosurgery for small-cell lung carcinoma brain metastases provided safe and effective local tumor control in the majority of patients.

Tyrosine hydroxylase (TH) deficiency is a rare autosomal recessive metabolic disease that results in the decreased production of catecholamines. Standard treatment relies on combinations of levodopa and carbidopa, anticholinergic agents, serotonergic agonists, and monamine oxidase B inhibitors. Unfortunately, severely affected children often require escalating doses of medication and suffer from dyskinesias as well as significant on/off symptomatology. The authors present a case of medically intractable dopa-responsive dystonia in a 6-year-old boy whose condition significantly improved with bilateral subthalamic nucleus deep brain stimulation. This case is unique in its novel approach to tyrosine hydroxylase deficiency and the young age of the patient.

OBJECT: The aim of this study was to evaluate the outcomes of Gamma Knife surgery (GKS) when used for patients with intractable cluster headache (CH). METHODS: Four participating centers of the North American Gamma Knife Consortium identified 17 patients who underwent GKS for intractable CH between 1996 and 2008. The median patient age was 47 years (range 26-83 years). The median duration of pain before GKS was 10 years (range 1.3-40 years). Seven patients underwent unsuccessful prior surgical procedures, including microvascular decompression (2 patients), microvascular decompression with glycerol rhizotomy (2 patients), deep brain stimulation (1 patient), trigeminal ganglion stimulation (1 patient), and prior GKS (1 patient). Fourteen patients had associated autonomic symptoms. The radiosurgical target was the trigeminal nerve (TN) root and the sphenopalatine ganglion (SPG) in 8 patients, only the TN in 8 patients, and only the SPG in 1 patient. The median maximum TN and SPG dose was 80 Gy. RESULTS: Favorable pain relief (Barrow Neurological Institute Grades I-IIIb) was achieved and maintained in 10 (59%) of 17 patients at a median follow-up of 34 months. Three patients required additional procedures (repeat GKS in 2 patients, hypothalamic deep brain stimulation in 1 patient). Eight (50%) of 16 patients who had their TN irradiated developed facial sensory dysfunction after GKS. CONCLUSIONS: Gamma Knife surgery for intractable, medically refractory CH provided lasting pain reduction in approximately 60% of patients, but was associated with a significantly greater chance of facial sensory disturbances than GKS used for trigeminal neuralgia.

OBJECT: To evaluate the role of stereotactic radiosurgery (SRS) in the management of brain metastases from melanoma, the authors assessed clinical outcomes and prognostic factors for survival and tumor control. METHODS: The authors reviewed 333 consecutive patients with melanoma who underwent SRS for 1570 brain metastases from cutaneous and mucosal/acral melanoma. The patient population consisted of 109 female and 224 male patients with a median age of 53 years. Two hundred eleven patients (63%) had multiple metastases. One hundred eighteen patients (35%) underwent whole-brain radiation therapy (WBRT). The target volume ranged from 0.1 cm(3) to 37.2 cm(3). The median marginal dose was 18 Gy. RESULTS: Actuarial survival rates were 70% at 3 months, 47% at 6 months, 25% at 12 months, and 10% at 24 months after radiosurgery. Factors associated with longer survival included controlled extracranial disease, better Karnofsky Performance Scale score, fewer brain metastases, no prior WBRT, no prior chemotherapy, administration of immunotherapy, and no intratumoral hemorrhage before radiosurgery. The median survival for patients with a solitary brain metastasis, controlled extracranial disease, and administration of immunotherapy after radiosurgery was 22 months. Sustained local tumor control was achieved in 73% of the patients. Sixty-four (25%) of 259 patients who had follow-up imaging after SRS had evidence of delayed intratumoral hemorrhage. Sixteen patients underwent a craniotomy due to intratumoral hemorrhage. Seventeen patients (6%) had asymptomatic and 21 patients (7%) had symptomatic radiation effects. Patients with