Minimally Invasive Retrosigmoidal Parasterional Burr-Hole Approach: Technique and Neuropathic Pain Amelioration after Microvascular Decompression of the Trigeminal Nerve.

BACKGROUND: Trigeminal neuralgia, a common condition in clinical practice, often occurs due to vascular compression caused by aberrant or ectopic arterial or venous vessels. Microvascular decompression through a minimally invasive retrosigmoidal approach has shown high rates of pain control, low complication rates, and excellent therapeutic results. OBJECTIVE: To describe the surgical technique and clinical outcomes in terms of pain relief after microvascular decompression of the trigeminal nerve through a minimally invasive retrosigmoidal parasterional burr-hole technique. METHODS: A group of patients with trigeminal neuralgia refractory to medical management who underwent microvascular decompression were examined. The records of the patients were considered retrospectively (2016-2018), and the outcomes were considered based on the Visual Analogue Scale (VAS) and the Barrow Neurological Institute Pain Scale (BNIPS) added to a technical note of the surgical technique for a minimally invasive retrosigmoidal parasterional burr-hole. RESULTS: Twenty-two patients were evaluated, and clinical assessment after surgical intervention showed a decrease in pain according to the VAS, resulting from an average preoperative state of 9.5 ± 0.37 to a postoperative condition of 1.32 ± 1.28, exhibiting statistically significant changes (p < 0.0001, d = 9.356). On the other hand, in relation to the BNIPS scale, a decrease from an average preoperative status of 4.55 ± 0.25 to a postoperative status at 12 months of 1.73 ± 0.54 was also demonstrated, showing significant changes (p < 0.0001, d = 3.960). CONCLUSION: Microvascular decompression of the trigeminal nerve through a minimally invasive retrosigmoidal parasterional burr-hole is feasible and can be a safe and effective technique for the management of pain. However, further research employing larger sample sizes and longer follow-up periods is necessary.

Radiofrequency Ablation of Prelemniscal Radiations for the Treatment of Non-Parkinsonian Tremor.

OBJECTIVE: Previous reports proposed prelemniscal radiations (Raprl) as a target to treat motor symptoms of Parkinson's disease, and this was found particularly effective to control rest and postural tremor. However, tremor of other etiologies has been seldom treated with deep brain stimulation or ablation in this target. We present a series of such cases successfully treated by Raprl radiofrequency (RF) lesions. MATERIAL AND METHODS: Six patients with predominant unilateral tremor on the right arm: 4 intention, 1 cerebellar and 1 rubral tremor, incapacitating in spite of at least 2 regimes of medical treatment at maximal tolerated doses, were operated under local anesthesia. RF lesions were performed in Raprl contralateral to most prominent symptoms. Patients had monthly evaluation of tremor severity through the Fahn-Tolosa-Marin Tremor Rating Scale and disability through the Tremor Disability Scale along a 1-year follow-up. RESULTS: In 4/6 patients tremor was stopped by the simple insertion of an RF electrode in Raprl; in the other 2 cases, stimulation through the RF electrode at 100 Hz, with 100 µs and 1.0-1.5 V, stopped the tremor without side effects. Tremor disappeared in all cases immediately after surgery and partially reappeared in 2 cases with an amplitude about 20% of the preoperative condition. RF lesions in postoperative MRI ranked from 1.8 to 2.6 mm in diameter. CONCLUSIONS: RF lesioning in Raprl is a simple, highly effective, inexpensive way to treat tremor of different etiologies.

Hemifacial Spasm Associated with Compression of the Facial Colliculus by a Choroid Plexus Papilloma of the Fourth Ventricle.

BACKGROUND: Hemifacial spasm is an involuntary condition that involves muscles innervated by the ipsilateral facial nerve. There are secondary causes of hemifacial spasm that can produce a typical presentation of symptoms. Extrinsic compression of the facial colliculus at the floor of the fourth ventricle is responsible for <0.6% of the causes of secondary hemifacial spasm, as the cases with this origin reported in the literature are rare. CASE REPORTS: We present the case of a 43-year-old female with hemifacial spasm of typical characteristics 6 months after onset. Upon clinical examination, a severe contraction of the orbicularis oculi, orbicularis oris, and superficial muscles of the neck displaying 50 crisis per hour was revealed. Brain magnetic resonance imaging showed absence of the facial nerve vascular loop in the cisternal portion, with evidence of an intraventricular tumor in relation with the medial portion of the fourth ventricle at the facial colliculus level, indicating a secondary origin of hemifacial spasm. Preoperative electromyography demonstrated irritative electric activity in the muscular branches of the facial nerve. A telovelar approach was performed to the fourth ventricle with intraoperative electrophysiology monitoring, with immediate resolution of the irritative activity after complete tumor resection. The result of the histopathologic study was a choroid plexus papilloma. CONCLUSION: Fourth ventricle tumors with extrinsic compression of the facial colliculus represent <0.6% of the causes of hemifacial spasm. Its relationship with choroid plexuses papilloma is being described as the first case reported in the literature. Clinical correlation, imaging, and intraoperative findings in conjunction with intraoperative electrophysiology recordings allow to predict the resolution of symptoms after resecting the lesion.

Planned Gamma Knife Boost After Chemoradiotherapy for Selected Sinonasal and Nasopharyngeal Cancers.

OBJECTIVE: To determine the feasibility of a Gamma Knife boost after intensity-modulated radiation therapy in combination with multimodal therapy in patients with nasopharyngeal carcinoma and sinonasal malignancies with skull base or cavernous sinus involvement. METHODS: Nine patients were treated with intensity-modulated radiation therapy followed by a Gamma Knife boost. In one case Gamma Knife was given as salvage treatment after resection. Five patients had sinonasal malignancies and 4 had nasopharyngeal carcinoma. The mean radiation therapy dose was 64.3 Gy (range, 54-70 Gy) at 2 Gy per fraction. The median interval from completion of radiation therapy to Gamma Knife boost was 2.2 months (range, 1-4 months). The most common indication for Gamma Knife boost was involvement of the cavernous sinus, which was identified in 7 patients. The median margin Gamma Knife dose delivered was 13 Gy (range, 12-20 Gy), with median prescription isodose of 50%. RESULTS: All patients tolerated the procedure well, with minimal toxicity. Local control rates were achieved in all patients and no acute grade 3-5 toxicity was observed. One patient experienced late grade 4 toxicity, which was potentially attributable to treatment. Distant failure occurred in 3 patients (1 patient with nasopharyngeal carcinoma and 2 patients with sinonasal malignancies). CONCLUSIONS: Planned Gamma Knife boost followed intensity-modulated radiation therapy is feasible, safe, and provides excellent local control in patients with sinonasal malignancies and nasopharyngeal carcinoma, particularly in cases with cavernous sinus involvement. Further follow-up will be necessary to determine the long-term effectiveness and complication profile.