Continuous vagal monitoring value in prevention of vocal cord paralysis following thyroid surgery.

OBJECTIVES/HYPOTHESIS: Continuous intraoperative neuromonitoring (CIONM) of the vagus nerve was proposed to obtained frequent repetitive electromyography (EMG) data to recognize early change in intraoperative function of the recurrent laryngeal nerve. We examine our initial experience using this technology. STUDY DESIGN: Retrospective review. METHODS: Data for all patients who underwent neck surgery by a single surgeon at a North American institution over a 5-year period were reviewed. CIONM was used in cases with possible higher risk of traction injury and according to surgeon preference. In these cases, stretch injury was established by warning alarm with threshold of ≥50% reduction in amplitude and/or ≥ 10% increase in latency. Preoperative and postoperative direct laryngoscopy was performed for all patients. RESULTS: A total of 879 endocrine neck surgeries were performed. CIONM was used to monitor 455 recurrent laryngeal nerves (RLNs) in 344 (39.1%) surgeries. An automatic periodic stimulation (APS) alarm detected impending nerve injury in 33 (9.6%) cases by 64.9% ± 12.7% decrease in amplitude and by 27.3% increase in latency in one case. A total loss of signal (LOS) was detected in 15 (4.36%) cases. The immediate release of causative retraction successfully preserved the nerves in all cases with impending injury; however, there was no improvement in the LOS cases. Other than the cases with LOS, postoperative laryngoscopy showed normal vocal cord function in all cases. CONCLUSIONS: APS technology is safe, feasible, and helpful in approximately 10% of cases in our series, which developed nascent neurapraxia adverse EMG changes associated with intraoperative RLN stretch that could be reversed intraoperatively. LEVEL OF EVIDENCE: 4. Laryngoscope, 128:2429-2432, 2018.

In vivo leukocyte-mediated brain microcirculatory inflammation: a comparison of osmotherapies and progesterone in severe traumatic brain injury.

BACKGROUND: Mannitol, hypertonic saline, and progesterone may blunt leukocyte recruitment after traumatic brain injury (TBI). We hypothesized that progesterone reduces pericontusional recruitment of leukocytes to a greater extent than either osmotherapy a day after TBI. METHODS: CD1 mice underwent controlled cortical impact and were treated with osmotherapy (mannitol and hypertonic saline) or progesterone. Thirty-two hours after TBI, live pial microscopy was used to evaluate leukocyte-endothelial interactions and immunohistochemistry was used for the detection of pericontusional tissue polymorphonuclear neutrophils. Neurologic recovery was assessed before sacrifice. RESULTS: Mannitol resulted in the lowest in vivo leukocyte recruitment compared with progesterone (795 ± 282 vs 1,636 ± 434 LEU/100 µm/minutes, P < .05). Mannitol also displayed lower tissue accumulation of leukocytes as compared with progesterone (5.7 ± 1.7 vs 15.2 ± .1 LEU/mm(2), P = .03). However, progesterone resulted in better neurologic recovery than either osmotherapy. CONCLUSIONS: Leukocyte recruitment to injured brain is lowest with mannitol administration. How different agents alter progression of secondary brain injury will require further evaluation in humans.

Neuroprotective effects of progesterone in traumatic brain injury: blunted in vivo neutrophil activation at the blood-brain barrier.

BACKGROUND: Progesterone (PRO) may confer a survival advantage in traumatic brain injury (TBI) by reducing cerebral edema. We hypothesized that PRO reduces edema by blocking polymorphonuclear (PMN) interactions with endothelium (EC) in the blood-brain barrier (BBB). METHODS: CD1 mice received repeated PRO (16 mg/kg intraperitoneally) or vehicle (cyclodextrin) for 36 hours after TBI. Sham animals underwent craniotomy without TBI. The modified Neurological Severity Score graded neurologic recovery. A second craniotomy allowed in vivo observation of pial EC/PMN interactions and vascular macromolecule leakage. Wet/dry ratios assessed cerebral edema. RESULTS: Compared with the vehicle, PRO reduced subjective cerebral swelling (2.9 ± .1 vs 1.2 ± .1, P < .001), PMN rolling (95 ± 1.8 vs 57 ± 2.0 cells/100 µm/min, P < .001), total EC/PMN adhesion (2.0 ± .4 vs .8 ± .1 PMN/100 µm, P < .01), and vascular permeability (51.8% ± 4.9% vs 27.1% ± 4.6%, P < .01). TBI groups had similar a Neurological Severity Score and cerebral wet/dry ratios (P > .05). CONCLUSIONS: PRO reduces live pericontusional EC/PMN and BBB macromolecular leakage after TBI. Direct PRO effects on the microcirculation warrant further investigation.