Lidia Cabañes-Martínez

Objective: Due to the absence of studies supporting the role of intraoperative neurophysiological monitoring (IONM) in intradural spinal tumors, this study evaluates the clinical outcome after these surgeries in relation to the use of the advanced intraoperative neurophysiological techniques. Methods: This is an observational, descriptive and retrospective study of two cohort groups in relation to the presence or absence of IONM during the intervention and the subsequent evaluation of the clinical and functional results in the short and medium terms. Ninety-six patients with extra- or intramedullary intradural spinal tumors operated on by the neurosurgery team of our center completed the current study. Results: We observed improvements in the Prolo, Brice and McKissock and McCormick scales scores in the monitored patients. These results examine the usefulness of IONM to preserve neurological functions and, therefore, its impact on quality of life. The rate of neurological deficits in the unmonitored patients was 14.5%, whereas it was 8.3% of the patients whose treatment included IONM. Conclusions: It is important to emphasize the importance of implementing IONM for early recognition of possible neurological damage, the improvement of postoperative functional outcomes, and for decreasing the rate of neurological complications. Significance: This study provides reliable results on the importance of IONM in intradural spinal tumor surgeries.

Deep brain stimulation of the subthalamic nucleus is efficient for the treatment of motor symptoms (i.e., tremors) in patients with Parkinson’s disease. Gait disorders usually appear during advanced stages of idiopathic Parkinson’s disease in up to 80% of patients and have an important impact on their quality of life. The effects of deep brain stimulation of the subthalamic nucleus on gait and balance are still controversial. For this reason, alternative targets have been considered, such as stimulation of the pedunculopontine nucleus and the pars reticulata of substantia nigra, involved in the integration of the functional connections for gait. Due to the proximity of the subthalamic nucleus to the substantia nigra, their combined stimulation is feasible and may lead to better outcomes, improving axial symptoms. Our objective was to prospectively compare simultaneous stimulation of both structures versus conventional subthalamic stimulation in improving gait disorders. In ten patients with advanced Parkinson’s disease, deep brain stimulation leads (eight linear contacts) were implanted, and gait analysis was performed 6 months after surgery in off-stimulation and after 4 weeks of dual or single subthalamic stimulation. An improvement in gait parameters was confirmed with both stimulation conditions, with better results with combined substantia nigra and subthalamic stimulation compared with conventional subthalamic stimulation. Further studies are needed to determine if this effect remains after long-term dual-target stimulation.

OBJECTIVE: Intraoperative neurophysiological monitoring (INM) allows obtaining real-time information on the functional integrity of nervous system structures. The objective of this article is to present the role of clinical neurophysiology in Urology in the identification and preservation, on the one hand, of the prostate neurovascular bundles in radical prostatectomy (RP), and of the pudendal nerve in the release of this in Pudendal Nerve Entrapment Syndrome (PNS). METHODS: A bipolar laparoscopic probe was used for intraoperative stimulation for both the identification in PNS and neurovascular bundles in RP, obtaining response at the external anal sphincter in the first one; and intracavernous pressure in the second through needle electrodes. RESULTS: Preservation of the periprostatic neurovascular bundles allows to increase rates of sexual potency and urinary continence after surgery. However, it has been shown that the innervation of the corpora cavernosa and the urinary sphincter has a variable disposition. Intraoperative neurostimulation allows the most precise identification and dissection of the vascular and nervous structures that surround the prostate. In the diagnosis of PNS, the neurophysiological study allows to rule out pathology at other levels, such as, primary muscular pathology of the anal sphincter. There are no pathognomonic neurophysiological findings of PNS. In addition, it allows the identification of the nerve during the laparoscopic release of the nerve at the entrance of the Alcock channel, as well as the evaluation of its functional integrity after the end of the dissection. CONCLUSIONS: The INM is a fundamental tool to allow an improved identification of nerve structures during RP and PNS in order to preserve them. It also helps with the diagnosis of PNS.

Purpose: The occurrence of urinary incontinence and erectile dysfunction after surgical treatment for prostate cancer is a significant and lingering problem. The aim of this study is to revise and improve older techniques of intraoperative cavernous nerve mapping already in use to improve accuracy and reliability. Methods: We prospectively studied this technique in 12 patients suffering from prostate cancer. Inhalation or intravenous anesthetic regimen was used with nondepolarizing muscle relaxants. Stimulation protocol was 30 Hz, 0.2 ms, 10 to 20 mA intensity and a maximum duration of 30 seconds. Recording was performed with a system for measuring pressure changes using a stainless steel needle electrode inside the cavernous bodies. Stimulation was systematically performed at three distinct moments during the surgery at various points. An increase or decrease in pressure of 4 cm of H₂0 in the cavernous bodies was considered a positive result and negative response when no changes occurred after 30 seconds of continuous stimulation. Results: Of patients, 91.6% had positive responses to initial stimulation. The anesthetic regimen did not appear to significantly influence the responses in our series. Conclusions: In light of the results of this study, the stimulation of the cavernous nerves may be a viable technique in the right context, which includes good patient selection (young patients with a localized tumor and with preserved potency). The major limitation is that mapping techniques are useful to localize functional nerves, but not to monitor function in a continuous manner.

Background: The onset of generalized seizures is a long debated subject in epilepsy. The relative roles of cortex and thalamus in initiating and maintaining the different seizure types are unclear. Objective: The purpose of the study is to estimate whether the cortex or the centromedian thalamic nucleus is leading in initiating and maintaining seizures in humans. Methods: We report human ictal recordings with simultaneous thalamic and cortical electrodes from three patients without anesthesia being assessed for deep brain stimulation (DBS). Patients 1 and 2 had idiopathic generalized epilepsy whereas patient 3 had frontal lobe epilepsy. Visual inspection was combined with nonlinear correlation analysis. Results: In patient 1, seizure onset was bilateral cortical and the belated onset of leading thalamic discharges was associated with an increase in rhythmicity of discharges, both in thalamus and cortex. In patient 2, we observed bilateral independent interictal discharges restricted to the thalamus. However, ictal onset was diffuse, with discharges larger in the cortex even though they were led by the thalamus. In patient 3, seizure onset was largely restricted to frontal structures, with belated lagging thalamic involvement. Conclusion: In human generalized seizures, the thalamus may become involved early or late in the seizure but, once it becomes involved, it leads the cortex. In contrast, in human frontal seizures the thalamus gets involved late in the seizure and, once it becomes involved, it lags behind the cortex. In addition, the centromedian nucleus of the thalamus is capable of autonomous epileptogenesis as suggested by the presence of independent focal unilateral epileptiform discharges restricted to thalamic structures. The thalamus may also be responsible for maintaining the rhythmicity of ictal discharges.