Usefulness of the H-Reflex for Intraoperative Monitoring of Thoracoabdominal Aneurysms.

PURPOSE: Intraoperative neurophysiologic monitoring in thoracoabdominal aneurysms (TAAA) is essential to avoid intraoperative spinal cord injury). Motor and somatosensory evoked potentials may be considered intraoperative tools for detecting spinal cord injury. H-reflex is a well-known neurophysiologic technique to evaluate L5-S1 root. Current evidence supports the observation that H-reflex changes may occur with spinal cord damage as high as the cervical level. This study aimed to evaluate the usefulness of the H-reflex in these surgeries. METHODS: The use of intraoperative H-reflex in TAAA monitoring was evaluated in 12 patients undergoing open or endovascular repair of TAAA for a period of four years (2016-2020) using somatosensory evoked potentials (SSEPs) and transcranial motor evoked potentials (TcMEPs) and bilateral H-reflex. RESULTS: Six neurophysiologic alarms were recorded in five of the 12 patients. Summarizing the neurophysiologic changes of our series, we considered a peripheral change when we detected a unilateral loss of SSEPs, TcMEPs, and H-reflex. Instead, we assumed a central change when we detected a unilateral or bilateral loss of TcMEPs and H-reflex with normal SSEPs, which we considered a sign of spinal cord ischemia. Interestingly H-reflex always changed significantly in combination with TcMEPs in the same fashion. CONCLUSIONS: According to our series, H-reflex can detect intraoperative changes with the same sensitivity as TcMEPs in TAAA surgeries. With the support of other techniques, it can be useful to localize the origin of the lesion (peripheral or central spinal cord), to help in surgical decision-making to avoid postoperative neurologic damage. Based on our results, we recommend the systematic use of H-reflex in TAAA surgeries.

Effects of deep brain stimulation on the kinematics of gait and balance in patients with idiopathic Parkinson's disease.

BACKGROUND: Advanced stages of idiopathic Parkinson's disease are often characterised by gait alterations and postural instability. Despite improvements in patients' motor symptoms after deep brain stimulation of the subthalamic nucleus, its effects on gait and balance remain a matter of debate. This study investigated the effects of deep brain stimulation on balance and kinematic parameters of gait. METHODS: The gait of 26 patients with advanced idiopathic Parkinson's disease was analysed before and after (between 3 and 6 months) after bilateral deep brain stimulation of the subthalamic nucleus. Computerised analysis was used to study cadence, number of cycles with the correct support sequence, number of cycles, duration of the cycle stages, and knee and ankle goniometry. Balance, postural instability, and mobility were assessed using the Tinetti and Timed Up and Go test. FINDINGS: After stimulation, the following changes were significant (p < 0.01): number of cycles with the correct support sequence, number of total cycles, and foot contact. Patients improved significantly (p < 0.01) in the Tinetti and Timed Up and Go tests, the risk factors for falls changed from high (median 17) to low (median 25), and they improved from minor dependence (statistical median 14) to normality (statistical median 8.70). INTERPRETATION: Deep brain stimulation to inhibit hyperactivity of the subthalamic nucleus was associated with an improvement in the space-time variables of gait and balance in patients with Parkinson's disease for up to 3-6 months. These results highlight the major role of the subthalamic nucleus in motor control mechanisms during locomotion and balance.

Combined Stimulation of the Substantia Nigra and the Subthalamic Nucleus for the Treatment of Refractory Gait Disturbances in Parkinson's Disease: A Preliminary Study.

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.

Neuromuscular involvement in COVID-19 critically ill patients.

OBJECTIVE: Coronavirus disease 2019 (COVID-19) has a high incidence of intensive care admittance due to the severe acute respiratory syndrome (SARS). Intensive care unit (ICU)-acquired weakness (ICUAW) is a common complication of ICU patients consisting of symmetric and generalised weakness. The aim of this study was to determine the presence of myopathy, neuropathy or both in ICU patients affected by COVID-19 and whether ICUAW associated with COVID-19 differs from other aetiologies. METHODS: Twelve SARS CoV-2 positive patients referred with the suspicion of critical illness myopathy (CIM) or polyneuropathy (CIP) were included between March and May 2020. Nerve conduction and concentric needle electromyography were performed in all patients while admitted to the hospital. Muscle biopsies were obtained in three patients. RESULTS: Four patients presented signs of a sensory-motor axonal polyneuropathy and seven patients showed signs of myopathy. One muscle biopsy showed scattered necrotic and regenerative fibres without inflammatory signs. The other two biopsies showed non-specific myopathic findings. CONCLUSIONS: We have not found any distinctive features in the studies of the ICU patients affected by SARS-CoV-2 infection. SIGNIFICANCE: Further studies are needed to determine whether COVID-19-related CIM/CIP has different features from other aetiologies. Neurophysiological studies are essential in the diagnosis of these patients.

[Intraoperative neurophysiological monitoring in radical prostatectomy and pudendal nerve surgical releasing.] / Monitorización neurofisiológica intraoperatoria en prostatectomía radical y liberación del nervio pudendo.

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.

OBJETIVO: La monitorización neurofisiológica intraoperatoria (MNI) permite obtener información en tiempo real sobre la integridad funcional de las estructuras del sistema nervioso. El objetivo de este trabajo exponer el papel de neurofisiología clínica en Urología en la identificación y preservación, por un lado, de los haces neurovasculares prostáticos en la prostatectomía radical (PR), y del nervio pudendo en la liberación de este en el Síndrome de Atrapamiento del Nervio Pudendo (SANP).MÉTODOS: Se empleó una sonda bipolar laparoscópica para la estimulación intraoperatoria tanto para la identificación en SANP como de haces neurovasculares en PR obteniéndose respuesta a nivel del esfínter anal en la primera y presión intracavernosa en la segunda por medio de electrodos de aguja. RESULTADOS: La presentación de los haces neurovasculares periprostáticos permite aumentar las tasas de potencia sexual y continencia urinaria. Si bien, posteriormente, se evidenció que la inervación de los cuerpos cavernosos y el esfínter urinario tiene disposición variable. La neuroestimulación intraoperatoria permite la identificación y disección más precisa de las estructuras vasculonerviosas que circundan la próstata. En el diagnóstico del SANP, el estudio neurofisiológico permite descartar patología a otros niveles, como por ejemplo patología primaria muscular del esfínter anal; así como, valorar las ramas del nervio pudendo. No existen hallazgos neurofisiológicos patognomónicos del SANP. Además, permite la identificación del nervio durante la liberación laparoscópica del nervio a la entrada del canal de Alcock, así como la evaluación de su integridad funcional tras finalizar la disección. CONCLUSIONES: La MNI es una herramienta fundamental para permitir una mejora en la identificación de estructuras nerviosas durante PR y SANP para poder preservarlas. Así mismo, ayuda con el diagnóstico de SANP.

Monitorización neurofisiológica intraoperatoria en prostatectomía radical y liberación del nervio pudendo / Intraoperative neurophysiological monitoring in radical prostatectomy and pudendal nerve surgical releasing

Objetivo: La monitorización neurofisiológica intraoperatoria (MNI) permite obtener información en tiempo real sobre la integridad funcional de las estructuras del sistema nervioso. El objetivo de este trabajo exponer el papel de neurofisiología clínica en Urología en la identificación y preservación, por un lado, de los haces neurovasculares prostáticos en la prostatectomía radical (PR), y del nervio pudendo en la liberación de este en el Síndrome de Atrapamiento del Nervio Pudendo (SANP). Métodos: Se empleó una sonda bipolar laparoscópica para la estimulación intraoperatoria tanto para la identificación en SANP como de haces neurovasculares en PR obteniéndose respuesta a nivel del esfínter anal en la primera y presión intracavernosa en la segunda por medio de electrodos de aguja. Resultados: La presentación de los haces neurovasculares periprostáticos permite aumentar las tasas de potencia sexual y continencia urinaria. Si bien, posteriormente, se evidenció que la inervación de los cuerpos cavernosos y el esfínter urinario tiene disposición variable. La neuroestimulación intraoperatoria permite la identificación y disección más precisa de las estructuras vasculonerviosas que circundan la próstata. En el diagnóstico del SANP, el estudio neurofisiológico permite descartar patología a otros niveles, como por ejemplo patología primaria muscular del esfínter anal; así como, valorar las ramas del nervio pudendo. No existen hallazgos neurofisiológicos patognomónicos del SANP. Además, permite la identificación del nervio durante la liberación laparoscópica del nervio a la entrada del canal de Alcock, así como la evaluación de su integridad funcional tras finalizar la disección. Conclusiones: La MNI es una herramienta fundamental para permitir una mejora en la identificación de estructuras nerviosas durante PR y SANP para poder preservarlas. Así mismo, ayuda con el diagnóstico de SANP

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 PN

Ipsilateral hemiparesis: the forgotten history of this paradoxical neurological sign.

OBJECTIVE: Establishing the neurological localization doctrine for the contralateral hemispheric control of motor functions in the second half of the 19th century, researchers faced the challenge of recognizing false localizing signs, in particular paradoxical or ipsilateral hemiparesis (IH). Despite tremendous progress in current methods of neuroradiological and electrophysiological exploration, a complete understanding of this phenomenon has yet to be attained. METHODS: The authors researched the well-described cases of hemiparesis/hemiplegia ipsilateral to an intracranial lesion published in the scientific literature in the pre-MRI era (before 1980). A comprehensive review of the physiopathological mechanisms proposed for paradoxical hemiparesis throughout this period, as well as the pathological evidence substantiating them, is provided. RESULTS: A collection of 75 patients with hemiparesis/hemiplegia ipsilateral to the primary intracranial lesion reported between 1858 and 1979 were eligible for analysis. Most cases occurred in adults with supratentorial, slowly developing, extraparenchymatous mass lesions, such as neoplasms (38%) or chronic subdural hematomas (36%). Physiopathological theories proposed by the neurologists who investigated IH can be grouped into 4 major concepts: 1) lack of anatomical decussation of the corticospinal tract; 2) impaired functional activation of the contralateral hemisphere by the lesioned dominant hemisphere through the callosal connections; 3) Kernohan's notch phenomenon, or mechanical injury of the contralateral cerebral peduncle against the free edge of the tentorium; and 4) cerebrovascular dysfunction involving the contralateral hemisphere owing to kinking and mechanical flattening of the carotid artery contralateral to the primary intracranial lesion. CONCLUSIONS: IH represents a still underdiagnosed paradoxical neurological phenomenon. With the aid of modern neuroradiological and neurophysiological methods, Kernohan's peduncle notch mechanism has been confirmed to cause IH in many of the cases reported in recent decades. Nevertheless, alternative functional and/or vascular mechanisms must be investigated further for unexplained IH cases, in particular for transitory IH without evidence of peduncle injury. The historical theories reviewed in this paper represent a conceptual framework that may be helpful for this purpose.

Novel Mapping Method for the Intraoperative Neurophysiologic Monitoring of Sexual Function During Prostate Surgery.

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.

Long-Term Effective Thalamic Deep Brain Stimulation for Neuropathic Tremor in Two Patients with Charcot-Marie-Tooth Disease.

BACKGROUND: It has been described that many Charcot-Marie-Tooth syndrome type 2 patients are affected by a very disabling type of tremor syndrome, the pathophysiology of which remains unclear. Deep brain stimulation (DBS) has been successfully applied to treat most types of tremors by implanting electrodes in the ventral intermediate nucleus of the thalamus (Vim). METHODS: We used DBS applied to the Vim in 2 patients with severe axonal inherited polyneuropathies who developed a disabling tremor. RESULTS: Both patients responded positively to stimulation, with a marked reduction of the tremor and with an improvement of their quality of life. CONCLUSION: We report 2 cases of tremor associated with a hereditary neuropathy with a good response to DBS.

The Role of Thalamus Versus Cortex in Epilepsy: Evidence from Human Ictal Centromedian Recordings in Patients Assessed for Deep Brain Stimulation.

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.

Large Amplitude Cortical Evoked Potentials in Nonepileptic Patients. Reviving an Old Neurophysiologic Tool to Help Detect CNS Pathology.

PURPOSE: Although large amplitude evoked potentials (EPs) are typically associated with progressive myoclonic epilepsy patients, giant EPs imply central nervous system (CNS) hyperexcitability and can be seen in various nonepileptic disorders. METHODS: We performed a retrospective chart review including history, physical examination, imaging and diagnostic studies of nonepileptic patients with large amplitude somatosensory evoked potentials (SSEPs) and visual evoked potentials (VEPs) during 2007 to 2013. Large amplitude EPs were defined as follows: VEPs (N75-P100) >18 µV; and SSEPs (N20-P25) >6.4 µV. Recording montage for VEPs was Oz-Cz and SSEPs C3'/C4'-Fz. RESULTS: Fifty-two patients (33 females, 19 males; age range, 9-90 years) were identified. No CNS pathology was detected in 7 patients. All remaining patients were diagnosed with new CNS disorders including: vascular (37%); myelopathies (13%); demyelinating (11%); space occupying lesions (8.7%); syringomyelia (8.7%); hydrocephalus (6.5%); Vitamin B-12 deficiency (4.3%); multiple system atrophy (4.3%); and toxins (2.2%). CONCLUSIONS: This study supports the notion that large amplitude EP implies CNS hyperexcitability and CNS disease. These results confirm the utility of EP studies in patients with suspected CNS pathology.

Análisis cuantitativo de la marcha en pacientes con enfermedad de Parkinson avanzada / Quantitative gait analysis in patients with advanced Parkinson’s disease

Objetivo. Describir las alteraciones de la marcha e inestabilidad postural en un grupo de pacientes con enfermedad de Parkinson (EP) avanzada. Pacientes y métodos. Se analizó la marcha de pacientes con EP en estadio avanzado on medicación. Por medio de un sistema de análisis computarizado del movimiento, se estudiaron las variables cinemáticas: cadencia, número de ciclos con apoyo correcto (ciclos HFPS), número de ciclos totales, duración de las fases del ciclo, electromiografía, y goniometría de rodilla y tobillo. La valoración clínica del equilibrio y la inestabilidad postural se completó con los tests Tinetti y Timed Up & Go. Resultados. El análisis mostró alteraciones en los parámetros espaciotemporales con respecto a los rangos de normalidad: disminución de los ciclos HFPS, aumento del número total de ciclos y alteración de la cadencia en muchos pacientes, y conservación de la cadencia media dentro de los límites de la normalidad, aumento de la duración de la fase de apoyo, disminución del apoyo monopodal y alteración del rango articular de la rodilla y el tobillo. Asimismo, se observó una alteración en las puntuaciones obtenidas en las escalas clínicas, que mostraban un aumento del factor de riesgo de caídas y dependencia leve. Conclusión. La cuantificación mediante análisis objetivo de las variables cinéticas y cinemáticas en los pacientes con EP puede emplearse como herramienta para establecer la influencia de las distintas alternativas terapéuticas en el trastorno de la marcha (AU)

Aim. To describe the gait disorders and postural instability in a group of patients with advanced Parkinson’s disease (PD). Patients and Methods. Gait was analysed in patients in advanced stages of PD on medication. Using a computerised analysis system, we studied the kinematic variables: cadence, number of correct gait cycles (HFPS cycles), total number of cycles, duration of the phases of the cycle, electromyography and a goniometric study of the knee and the ankle. The clinical appraisal of balance and postural instability was completed with the Tinetti and Timed Up & Go tests. Results. The analysis showed alterations in the spatio-temporal parameters with respect to the ranges considered to be normal: reduction of the HFPS cycles, increase in the total number of cycles and alteration of the cadence in many patients. It also revealed that the mean cadence was kept within the limits of normal values, an increase in the duration of the contact phase, reduction of monopodal support and alteration of the joint range of motion of the knee and the ankle. Likewise, changes are also observed in the scores obtained on the clinical scales, which show an increase in the risk factor for falls and mild dependence. Conclusion. Quantification by objective analysis of the kinetic and kinematic variables in patients with PD can be used as a tool to establish the influence of the different therapeutic alternatives in gait disorders (AU)