Sharps Injuries Related to Subdermal Needles in the Orbicularis Oris During Intraoperative Neurophysiologic Monitoring.

PURPOSE: Little is known about the incidence and nature of sharps injuries caused by subdermal intraoperative neurophysiologic monitoring (IONM) needle electrodes. In their institution, the authors observed a series of sharps injuries attributed to placement of needles in the orbicularis oris (OO). METHODS: One large academic institution's sharps injury monitoring database was queried for all reported events over 3 years. The de-identified list was filtered for sharps events occurring in the operating room, and the descriptions of the sharps injuries were individually evaluated. Interventions were performed to attempt to decrease the number of sharps injuries from IONM needles, particularly those placed in OO. Similar data were then collected for 3 months post-intervention. RESULTS: Pre-intervention, 327 sharps injuries were reported over the span of 3 years, of which 13 (4.0%) were attributed to IONM needles not in OO and 5 (1.5%) were attributed to IONM needles in OO. Post-intervention, 41 sharps injuries were reported in 3 months, of which 5 (12.2%) were attributed to IONM needles not in OO and 1 (2.4%) was attributed to needles in OO. CONCLUSIONS: The placement of subdermal needles in the OO presents a disproportionately high risk of sharps injury. Interventions were performed to attempt to decrease the rate of sharps injuries from needles in OO; the post-intervention increase in events was likely skewed by small sample sizes. The implementation of these changes and the ongoing surveillance of injury cases may be important data to help decrease the number of sharps injuries attributed to IONM needles.

Direct brainstem somatosensory evoked potentials for cavernous malformations.

OBJECTIVE: Brainstem cavernous malformations (CMs) often require resection due to their aggressive natural history causing hemorrhage and progressive neurological deficits. The authors report a novel intraoperative neuromonitoring technique of direct brainstem somatosensory evoked potentials (SSEPs) for functional mapping intended to help guide surgery and subsequently prevent and minimize postoperative sensory deficits. METHODS: Between 2013 and 2019 at the Stanford University Hospital, intraoperative direct brainstem stimulation of primary somatosensory pathways was attempted in 11 patients with CMs. Stimulation identified nucleus fasciculus, nucleus cuneatus, medial lemniscus, or safe corridors for incisions. SSEPs were recorded from standard scalp subdermal electrodes. Stimulation intensities required to evoke potentials ranged from 0.3 to 3.0 mA or V. RESULTS: There were a total of 1 midbrain, 6 pontine, and 4 medullary CMs-all with surrounding hemorrhage. In 7/11 cases, brainstem SSEPs were recorded and reproducible. In cases 1 and 11, peripheral median nerve and posterior tibial nerve stimulations did not produce reliable SSEPs but direct brainstem stimulation did. In 4/11 cases, stimulation around the areas of hemosiderin did not evoke reliable SSEPs. The direct brainstem SSEP technique allowed the surgeon to find safe corridors to incise the brainstem and resect the lesions. CONCLUSIONS: Direct stimulation of brainstem sensory structures with successful recording of scalp SSEPs is feasible at low stimulation intensities. This innovative technique can help the neurosurgeon clarify distorted anatomy, identify safer incision sites from which to evacuate clots and CMs, and may help reduce postoperative neurological deficits. The technique needs further refinement, but could potentially be useful to map other brainstem lesions.

Retrospective Waveform Analysis of Transcranial Motor Evoked Potentials (MEP) to Identify Early Predictors of Impending Motor Deficits in Spinal Surgeries.

PURPOSE: Although there are guidelines analyzing transcranial motor evoked potentials (MEP) waveform criteria, they vary widely and are not applied universally during intraoperative neurophysiologic monitoring (IONM). The objective is to generate hypotheses to identify early and reliable MEP waveform characteristics prior to complete loss of MEP to predict impending motor spinal cord injuries during spinal surgeries. The ultimate goal is to enhance real-time feedback to prevent injury or detect reversible spinal cord damage. METHODS: Fifteen true positive cases of persistent intraoperative MEP loss and new postoperative motor deficits were retrospectively identified from 2011 to 2013. Waveform characteristics of latency, amplitude, duration, phases, and area-under-the-curve (AUC) were measured, and an intraoperative spinal cord index (ISCI) was calculated for 5 traces prior to complete MEP loss. ISCI = [amplitude x duration x (phases+1) x AUC]/latency. RESULTS: Out of 22 muscles in 15 cases, latency increased in 2, duration decreased in 12, amplitude decreased in 13, AUC decreased in 13, and ISCI decreased in 14. In 11 out of 15 cases (73%), ISCI dropped > 40% in at least one muscle before MEP were completely lost. Thirteen cases had concurrent somatosensory evoked potentials (SSEP) changes, 9 out of 13 had > 50% decrease in SSEP: 2 out of 9 changed before MEP, 5 out of 9 simultaneously, and 2 out of 9 after. CONCLUSIONS: In these cases of motor injury, smaller and simpler MEP waveforms preceded complete loss of signal. An ISCI 40% drop could be tested as a warning threshold for impending motor compromise in future prospective studies and lead to eventual standardization to predict irreversible postoperative deficits.

Detection of inferolateral trunk syndrome by neuromonitoring during catheter angiography with provocative testing.

BACKGROUND AND IMPORTANCE: It is not uncommon that endovascular balloon test occlusion (BTO) is performed to assess collateral blood flow and risk of injury of permanent occlusion of the internal carotid artery (ICA). This case is the first reported of detection and reversal of the inferolateral trunk (ILT) syndrome in an awake patient during provocative BTO; prompt recognition of the syndrome effectively prevented permanent neurologic deficits. CLINICAL PRESENTATION: The case of a 42-year-old woman is reported who had a left sphenoid wing meningioma with extension into the cavernous sinus and who underwent awake catheter angiography with provocative BTO of the ICA. Serial examinations by intraoperative monitoring neurologists and neurointerventionalists detected acute progressive left retro-orbital pressure followed by sudden inability to adduct the left eye, or a left medial rectus palsy, indicative of the ILT syndrome which led to immediate balloon deflation and resolution of the deficits. The hypothesis was that hypoperfusion of the ILT, an arterial branch of the ICA which provides blood supply to several cranial nerves (CN) III, CN V1 and CN V2, caused her acute symptoms. CONCLUSION: Although cerebral ischemia is a well known complication of endovascular procedures, CN ischemia is a rare potential risk. Knowledge of cerebrovascular anatomy and serial examinations prevented neurologic deficits; this case underscores the added utility of examinations by intraoperative monitoring neurologists and interdisciplinary collaboration.

Utility of electrodiagnostic testing in evaluating patients with lumbosacral radiculopathy: An evidence-based review.

This is an evidence-based review of electrodiagnostic (EDX) testing of patients with suspected lumbosacral radiculopathy to determine its utility in diagnosis and prognosis. Literature searches were performed to identify articles applying EDX techniques to patients with suspected lumbosacral radiculopathy. From the 355 articles initially discovered, 119 articles describing nerve conduction studies, electromyography (EMG), or evoked potentials in adequate detail were reviewed further. Fifty-three studies met inclusion criteria and were graded using predetermined criteria for classification of evidence for diagnostic studies. Two class II, 7 class III, and 34 class IV studies described the diagnostic use of EDX. One class II and three class III articles described H-reflexes with acceptable statistical significance for use in the diagnosis and confirmation of suspected S1 lumbosacral radiculopathy. Two class II and two class III studies demonstrated a range of sensitivities for use of muscle paraspinal mapping. Two class II studies demonstrated the utility of peripheral myotomal limb electromyography in radiculopathies.

Chemotherapy-related polyneuropathy may deteriorate quality of life in patients with B-cell lymphoma.

PURPOSE: This prospective study was performed to evaluate the effect of chemotherapy-related neurotoxicity on quality of life (QOL) of patients with lymphoma. METHODS: Thirty-two patients with diffuse large B-cell or follicular lymphoma without prior evidence of neuropathy were enrolled. Patients underwent the evaluations based on neuropathy symptom and disability score, nerve conduction studies, and SF-36 questionnaire for QOL assessment. They received six cycles of chemotherapy every three weeks, and all evaluations were repeated during and after the completion of 6th cycle. RESULTS: Sensory neuropathy-associated symptoms were observed in 27 patients (84.4%), and polyneuropathy was confirmed by nerve conduction study in 14 patients (43.8%). These patients with polyneuropathy showed worse QOL in domains mainly associated with physical health status including "physical function" compared to patients without polyneuropathy. There was a significant association of neuropathy symptom and disability scores with "bodily pain" and "vitality" of QOL domains. The serial evaluations of patients with neuropathy showed a worsening of QOL and neuropathy symptom scores during chemotherapy, then improvement of these values after chemotherapy. Thus, the final nerve conduction study confirmed the decrease in polyneuropathy compared to the 2nd evaluation (P = 0.032). CONCLUSION: Chemotherapy-related polyneuropathy may deteriorate QOL of patients with lymphoma, mainly physical health-associated QOL.

Utility of the cutaneous silent period in the evaluation of carpal tunnel syndrome.

OBJECTIVE: This study investigates the utility of the cutaneous silent period (CuSP) in evaluating patients with carpal tunnel syndrome (CTS). METHODS: The authors measured the CuSP from the abductor pollicis brevis muscle in 135 hands of patients with idiopathic CTS and 30 hands of age- and gender-matched controls. The patient group was further divided into subgroups according to the Canterbury scale. The differences in parameters between the patient subgroups and control group were analysed. A predetermined analysis looked at the possible correlation between the CuSP and symptom severity as measured by the Boston-Questionnaire. RESULTS: The mean CuSP latencies in the patient group (72.4+/-16.1 ms) was significantly longer than the control group (64.6+/-13.4 ms; P=0.014), although there was no difference in the duration of the CuSP between groups. The duration and latency of the CuSP correlated to a higher severity on the Canterbury scale (r=0.273, P<0.001 and r=-0.164, P=0.036, respectively). However, the CuSP parameters did not correlate with the Boston-Questionnaire scores. CONCLUSIONS: Although patients with CTS had significantly prolonged CuSP latency, the CuSP did not correlate with the clinical symptoms scale. SIGNIFICANCE: The CuSP is a useful ancillary test to evaluate Adelta fibre function; however, it is not a reliable tool to quantify clinical severity.

Utility of the cutaneous silent period in patients with diabetes mellitus.

We performed this study to evaluate whether or not the cutaneous silent period (CSP) is a useful metric to identify small-fiber neuropathy in diabetic patients. The CSP was measured from the abductor pollicis brevis muscle in 30 healthy controls and 110 diabetic patients, who in turn were divided into 3 subgroups (patients with large-fiber neuropathy, patients with small-fiber neuropathy, and asymptomatic patients). The measured CSP and clinical characteristics were compared among the groups. The power of the CSP in discriminating patients from controls and any correlation with other clinical variables were analyzed. Each patient subgroup had a significantly delayed CSP latency compared to the controls. The latency of patients with large-fiber neuropathy was also significantly prolonged compared to the other subgroups of patients. The CSP latency was the only variable to discriminate patients. The latency showed a significant correlation with the late responses in nerve conduction studies. Thus, the CSP latency may be a useful tool in evaluating small neural fiber function in diabetic patients.

Driving with polyneuropathy.

Polyneuropathy may result in pain, numbness, and weakness, which may in turn affect driving ability. Medications used to treat neuropathic pain may alter cognition, which may further affect driving. Although such impairments have engendered questions about the driving safety in this group of patients, the rate of motor vehicle accidents (MVAs) in patients with neuropathy has not been studied rigorously. We surveyed patients with neuropathy from three medical centers for reported accident rate, and we analyzed variables related to increased risk for accidents compared to National Highway Traffic Safety Administration data. Surveys from 260 subjects demonstrated that 40.6% were involved in traffic accidents (0.11 accidents/year). Their accident rate was 10.8 MVAs per million vehicle miles traveled (MVA/MVMT), compared to 3.71 MVA/MVMT in 55-59-year-old drivers and 3.72 in 60-64-year-olds (National Highway Traffic Safety Administration data). In all, 72.4% cited their neuropathy and 55.2% cited their medications as playing a role in their accidents, and 51.6% changed their driving habits after developing neuropathy. Independently, elevated levels of pain, motor weakness, and ambulation difficulty met statistical significance for increased MVA frequency. We conclude that accident frequency and discomfort with driving are higher in neuropathy patients compared to age-matched national statistics. However, most patients seem to change habits according to their ability to drive; as such, driving issues should be addressed with caution and on a case-by-case basis.

Clinical utility of electrodiagnostic consultation in suspected polyneuropathy.

Although paresthesias of the distal lower limbs are characteristic features of polyneuropathy, they may also herald the presence of a focal neuropathy, polyradiculopathy, or myelopathy. Electromyography and nerve conduction studies (EMG/NCS) are widely used in the evaluation of such symptoms, but their utility has not been subjected to vigorous scrutiny. We investigated the clinical impact of the electrodiagnostic consultation in assessing suspected polyneuropathy. When compared with the clinical impression, the result of the electrodiagnostic consultation was confirmatory in only 39% of all patients, and changed the diagnosis or uncovered an additional diagnosis in 43%. An alternative diagnosis was likely when either weakness was present (75%) or the Achilles stretch reflex was preserved (48%). These data support the use of EMG/NCS in the diagnostic evaluation of patients presenting with distal paresthesias, especially in those with preserved Achilles reflexes or motor deficits.