Microvascular Decompression After Gamma Knife Surgery for Trigeminal Neuralgia: Intraoperative Findings and Treatment Outcomes

Object. The authors sought to determine whether the results of trigeminal microvascular decompression (MVD) are influenced by prior gamma knife surgery (GKS). Methods. Gamma knife surgery is an established procedure for treating medically intractable trigeminal neuralgia but failures do occur. The authors assessed six patients (two men and four women; mean age 52 years) who experienced pain recurrence after GKS and elected to undergo trigeminal MVD via retrosigmoid craniotomy. Three patients underwent a single GKS to a maximal dose of 80 Gy, whereas three others underwent a second GKS to total of 120 to 135 Gy. At surgery, none of the six patients demonstrated excess arachnoid thickening, grossly apparent changes in the nerve itself, or any other tissue alterations that made successful mobilization of a blood vessel from the trigeminal root entry zone technically more difficult. A single individual had a small atherosclerotic plaque in the superior cerebellar artery near its contact point with the trigeminal nerve. Follow up at a mean of 25.4 months (range 7.5-42 months) indicated that five patients were pain free. One patient had improved but still relied on medications for pain control. Conclusions. In the authors\u27 experience, trigeminal MVD can be performed without added difficulty in patients who have previously undergone GKS. The success rates seem similar to those normally associated with MVD. Patients who elect the less invasive option of GKS can be assured that trigeminal MVD remains a viable alternative at a later date if further surgery is required

Gamma knife radiosurgery for trigeminal neuralgia associated with multiple sclerosis.

OBJECT: The authors assessed the efficacy and complications from gamma knife radiosurgery (GKS) for multiple sclerosis (MS)-associated trigeminal neuralgia (TN). METHODS: There were 15 patients with MS-associated TN (MS-TN). Treatment involved three sequential protocols, 70 to 90-Gy maximum dose, using a single 4-mm isocenter targeting the ipsilateral trigeminal nerve at its junction with the pons with the 50% isodose. Pain was appraised by each patient by using Barrow Neurological Institute (BNI) Scores I through IV: I, no pain; II, occasional pain not requiring medication; IIIa, no pain but continued medication; IIIb, some pain, controlled with medication; IV, some pain, not controlled with medication; and V, severe pain/no pain relief. With a mean follow up of 17 months (range 6-38 months), 12 (80%) of 15 patients experienced pain relief. Three patients (20%) reported no relief (BNI Score V). For responders, the mean latency from treatment to the onset of pain relief was 13 days (range 1-61 days). Maximal relief was achieved after a mean latency of 56 days (range 1-157 days). Five patients underwent a second GKS after a mean interval of 534 days (range 231-946 days). The mean maximum dose at this second treatment was 48 Gy. The target was unchanged from the first treatment. All five patients who underwent repeated GKS improved. Complications were limited to delayed facial hypesthesias. Two (13%) of 15 patients experienced onset of numbness after the first GKS, as well as two of five patients following a second GKS. The patients found this mild and not bothersome. Each patient who developed hypesthesias also experienced complete pain relief. CONCLUSIONS: Gamma knife radiosurgery is an effective treatment for MS-TN. Radiosurgery carries an acceptable small risk of mild facial hypesthesias, and hypesthesia appears predictive of a favorable outcome

Gamma knife radiosurgery for recurrent trigeminal neuralgia.

OBJECT: Pain may fail to respond or may recur after initial gamma knife radiosurgery (GKS) for trigeminal neuralgia (TN). The authors examined their experience with performing a second GKS procedure in these patients. METHODS: Twenty-nine patients underwent repeated GKS for TN at our institution between March 1997 and March 2002. Questionnaires were mailed to patients to assess the degree of their pain relief and the extent of facial numbness. Nineteen patients responded. All patients underwent repeated GKS involving a single 4-mm isocenter directed at the trigeminal nerve as it exited the brainstem (mean maximum dose 23.2 Gy). At a mean follow up of 13.5 months after the second procedure, 10 patients (53%) were pain free and medication free. Four patients (21%) were pain free but elected to continue medication in reduced dose, and two patients (11%) had incomplete but satisfactory pain control and were still taking medication. There was new-onset facial numbness in eight patients (42%), rated as tolerable in all instances. CONCLUSIONS: Patients with facial numbness had a greater likelihood of being pain free than those with no sensory loss. The authors observed no cases of corneal anesthesia, keratitis, or deafferentation pain

Effect of recombinant human bone morphogenetic protein-2 in an experimental model of spinal fusion in a radiated area

Study Design. An animal model of posterolateral intertransverse process spine fusion was used. Objectives. To investigate whether recombinant human bone morphogenetic protein-2 (rhBMP-2) can overcome the adverse effects of radiation treatment (RT) on spine fusion. Summary of Background Data. Spinal metastases are common. Some of these patients are candidates for spinal cord decompression and vertebral reconstruction; however, radiation has significant adverse effects on bone healing. Methods. A posterolateral fusion model was used with rhBMP-2 or iliac crest bone graft (ICBG). Eighty one-year-old rabbits were divided into eight groups: 1) RT 14 days before surgery, rhBMP-2; 2) RT 14 days before surgery, ICBG; 3) RT 2 days after surgery, rhBMP-2; 4) RT 2 days after surgery, ICBG; 5) RT 14 days after surgery, rhBMP-2; 6) RT 14 days after surgery, ICBG; 7) no RT, rhBMP-2; 8) no RT, ICBG. Animals were killed approximately 35 days after surgery. Manual palpation was the definitive test of fusion. Biomechanical and histologic assessments were also performed. Results. All rhBMP-2 groups had significantly greater fusion rates versus respective ICBG control groups: 1 (86%) versus 2 (0%) (P = 0.005), 3 (100%) versus 4 (0%) (P \u3c 0.0001), 5 (100%) versus 6 (0%) (P \u3c 0.0001), and 7 (100%) versus 8 (60%) (P = 0.003). Stiffness and ultimate strength did not differ significantly between the experimental and control groups. Histologic assessment confirmed new bone formation in the fusion masses from rhBMP-2 groups. Conclusions. Use of rhBMP-2 produced a significantly greater rate of fusion compared with ICBG in a previously radiated area in an animal model, without the morbidity of ICBG harvesting and without the risk of inadvertently using autograft contaminated by micrometastases. ©2005, Lippincott Williams & Wilkins, Inc