Warning criteria for MEP monitoring during carotid endarterectomy: a retrospective study of 571 patients.

Monitoring of transcranial electrical motor evoked potentials (tcMEP) during carotid endarterectomy (CEA) has been shown to effectively detect intraoperative cerebral ischemia. The unique purpose of this study was to evaluate changes of MEP amplitude (AMP), area under the curve (AUC) and signal morphology (MOR) as additional MEP warning criteria for clamping-associated ischemia during CEA. Therefore, the primary outcome was the number of MEP alerts (AMP, AUC and MOR) in the patients without postoperative motor deficit (false positives). We retrospectively reviewed data from 571 patients who received CEA under general anesthesia. Monitoring of somatosensory evoked potentials (SSEP) and tcMEP was performed in all cases (all-or-none MEP warning criteria). The percentages of false positives (primary parameter) of AMP, AUC and MOR were evaluated according to the postoperative motor outcome. In the cohort of 562 patients, we found significant SSEP/MEP changes in 56 patients (9.96%). In 44 cases (7.83%) a shunt was inserted. Nine patients (1.57%) were excluded due to MEP recording failure. False positives were registered for AMP, AUC and MOR changes in 121 (24.01%), 148 (29.36%) and 165 (32.74%) patients, respectively. In combination of AMP/AUC and AMP/AUC/MOR false positives were found in 9.52% and 9.33% of the patients. This study is the first to evaluate the correctness of the MEP warning criteria AMP, AUC and MOR with regard to false positive monitoring results in the context of CEA. All additional MEP warning criteria investigated produced an unacceptably high number of false positives and therefore may not be useful in carotid surgery for adequate detection of clamping-associated ischemia.

Walking assessment after lumbar puncture in normal-pressure hydrocephalus: a delayed improvement over 3 days.

OBJECTIVE The determination of gait improvement after lumbar puncture (LP) in idiopathic normal-pressure hydrocephalus (iNPH) is crucial, but the best time for such an assessment is unclear. The authors determined the time course of improvement in walking after LP for single-task and dual-task walking in iNPH. METHODS In patients with iNPH, sequential recordings of gait velocity were obtained prior to LP (time point [TP]0), 1-8 hours after LP (TP1), 24 hours after LP (TP2), 48 hours after LP (TP3), and 72 hours after LP (TP4). Gait analysis was performed using a pressure-sensitive carpet (GAITRite) under 4 conditions: walking at preferred velocity (STPS), walking at maximal velocity (STMS), walking while performing serial 7 subtractions (dual-task walking with serial 7 [DTS7]), and walking while performing verbal fluency tasks (dual-task walking with verbal fluency [DTVF]). RESULTS Twenty-four patients with a mean age of 76.1 ± 7.8 years were included in this study. Objective responder status moderately coincided with the self-estimation of the patients with subjective high false-positive results (83%). The extent of improvement was greater for single-task walking than for dual-task walking (p < 0.05). Significant increases in walking speed were found at TP2 for STPS (p = 0.042) and DTVF (p = 0.046) and at TP3 for STPS (p = 0.035), DTS7 (p = 0.042), and DTVF (p = 0.044). Enlargement of the ventricles (Evans Index) positively correlated with early improvement. Gait improvement at TP3 correlated with the shunt response in 18 patients. CONCLUSIONS Quantitative gait assessment in iNPH is important due to the poor self-evaluation of the patients. The maximal increase in gait velocity can be observed 24-48 hours after the LP. This time point is also best to predict the response to shunting. For dual-task paradigms, maximal improvement appears to occur later (48 to 72 hours). Assessment of gait should be performed at Day 2 or 3 after LP.

Falls and fear of falling in vertigo and balance disorders: A controlled cross-sectional study.

BACKGROUND: Vertigo and dizziness are among the most prevalent symptoms in neurologic disorders. Although many of these patients suffer from postural instability and gait disturbances, there is only limited data on their risk of falling. METHODS: We conducted a controlled cross-sectional study at the tertiary care outpatient clinic of the German Center for Vertigo and Balance Disorders using a self-administered questionnaire to assess falls, fall-related injuries, and fear of falling. The recruitment period was 6 months. RESULTS: A total of 569 patients (mean age 59.6 ± 17.1 years, 55% females) and 100 healthy participants were included (response rate > 90%). Dizzy patients with central balance disorders (Parkinsonian, cerebellar, and brainstem oculomotor syndromes) had the highest fall rates (> 50% recurrent fallers, odds ratio > 10). The rate of recurrent fallers was 30% in bilateral vestibular failure and peripheral neuropathy (odds ratio > 5). Patients with functional dizziness (somatoform or phobic vertigo) were concerned about falling but did not fall more often than healthy controls (odds ratio 0.87). CONCLUSION: Falls are common in patients presenting to a dizziness unit. Those with central syndromes are at risk of recurrent and injurious falling. Fall rates and fear of falling should be assessed in balance disorders and used to guide the regimen of rehabilitation therapy. The identification of risk factors would help provide protective measures to these groups of patients.