Fabio Raneri

Tailoring neurophysiological strategies with clinical context enhances resection and safety and expands indications in gliomas involving motor pathways

BACKGROUND Resection of motor pathway gliomas requires the intraoperative recognition of essential cortical-subcortical motor structures. The degree of involvement of motor structures is variable, and increases as result of treatments patients are submitted to. Intraoperative neurophysiology offers various stimulation modalities, which efficiency is based on the ability to recognize essential sites with the highest possible resolution in most clinical conditions. Two stimulation paradigms evolved for intraoperative guidance of motor tumors removal: the 60 Hz-technique [low frequency (LF)] and the pulse-technique [high frequency-(HF)], delivered by bipolar or monopolar probe respectively. Most surgical teams rely on to either of the 2 techniques. The key point is the integration of the choice of the stimulation modality with the clinical context. METHODS In 591 tumors involving the corticospinal tract, the use of HF and LF was tailored to the clinical context defined by patient clinical history and tumor features (by imaging). The effect was evaluated on the feasibility of mapping, the impact on immediate and permanent morbidity, the extent of resection, and the number of patients treated. RESULTS By integrating the choice of the probe and the stimulation protocol with patient clinical history and tumor characteristics, the best probe-frequency match was identified for the different sets of clinical conditions. This integrative approach allows increasing the extent of resection and patient functional integrity, and greatly expands the number of patients who could benefit from surgery. CONCLUSIONS The integration of stimulation modalities with clinical context enhances the extent and safety of resection and expands the population of patients who could benefit from surgical treatment.

Monopolar high-frequency language mapping: can it help in the surgical management of gliomas? A comparative clinical study

OBJECT Intraoperative language mapping is traditionally performed with low-frequency bipolar stimulation (LFBS). High-frequency train-of-five stimulation delivered by a monopolar probe (HFMS) is an alternative technique for motor mapping, with a lower reported seizure incidence. The application of HFMS in language mapping is still limited. Authors of this study assessed the efficacy and safety of HFMS for language mapping during awake surgery, exploring its clinical impact compared with that of LFBS. METHODS Fifty-nine patients underwent awake surgery with neuropsychological testing, and LFBS and HFMS were compared. Frequency, type, and site of evoked interference were recorded. Language was scored preoperatively and 1 week and 3 months after surgery. Extent of resection was calculated as well. RESULTS High-frequency monopolar stimulation induced a language disturbance when the repetition rate was set at 3 Hz. Interference with counting (p = 0.17) and naming (p = 0.228) did not vary between HFMS and LFBS. These results held true when preoperative tumor volume, lesion site, histology, and recurrent surgery were considered. Intraoperative responses (1603) in all patients were compared. The error rate for both modalities differed from baseline values (p < 0.001) but not with one another (p = 0.06). Low-frequency bipolar stimulation sensitivity (0.458) and precision (0.665) were slightly higher than the HFMS counterparts (0.367 and 0.582, respectively). The error rate across the 3 types of language errors (articulatory, anomia, paraphasia) did not differ between the 2 stimulation methods (p = 0.279). CONCLUSIONS With proper setting adjustments, HFMS is a safe and effective technique for language mapping.

Surgical brain metastases: management and outcome related to prognostic indexes: a critical review of a ten-year series.

Brain metastasis are the most common neoplastic lesions of the nervous system. Many cancer patients are diagnosed on the basis of a first clinical presentation of cancer on the basis of a single or multiple brain lesions. Brain metastases are manifestations of primary disease progression and often determine a poor prognosis. Not all patients with a brain metastases undergo surgery: many are submitted to alternative or palliative treatments. Management of patients with brain metastases is still controversial, and many studies have been developed to determine which is the best therapy. Furthermore, management of patients operated for a brain metastasis is often difficult. Chemotherapy, stereotactic radiosurgery, panencephalic radiation therapy, and surgery, in combination or alone, are the means most commonly used. We report our experience in the management of a ten-year series of surgical brain metastasis and discuss our results in the preoperative and postoperative management of this complex condition.

Supplementary Tests in Idiopathic Normal Pressure Hydrocephalus: A Single-Center Experience with a Combined Lumbar Infusion Test and Tap Test

BACKGROUND The lumbar infusion test (LIT) and tap test (TT) have previously been described for the diagnosis and selection of appropriate surgical candidates in idiopathic normal pressure hydrocephalus (iNPH). METHODS We retrospectively reviewed 81 consecutive patients with a clinical diagnosis of iNPH selected for supplementary testing. Clinical evaluation was scored with the Japanese Grading Scale for Normal Pressure Hydrocephalus, the Global Deterioration Score, and the modified Rankin Scale (mRS). The test protocol included a cerebrospinal fluid pressure monitoring (PMi), an LIT, and a TT. Patients were selected for surgery if outflow resistance was ≥14 mm Hg/mL/minute or if a clinical improvement was recorded after TT. RESULTS Sixty-eight patients were selected for ventriculoperitoneal shunting; 72.8% had a positive PMi or LIT, 74.1% had a positive TT, and 63.0% were positive to both tests. Complications were all transient. Clinical evaluation at 12 months after shunting showed a global improvement in 60 patients (88.2%). Overall, 75.0% of patients had no significant disability (mRS score, 1 and 2), 20.6% had an mRS score of 3 or 4, and 4.4% had severe disability after surgery. The positive predictive value of PMi/LIT, TT, or both combined was similar (89.8, 90.0, and 88.2%); however, 21.7% of patients who improved after surgery were selected with either a positive LIT or TT alone. CONCLUSIONS LIT and TT are complementary and they can easily be combined in sequence with a low complication rate and high probability of selecting patients with iNPH who may benefit from ventriculoperitoneal shunt surgery.