The laryngeal twitch response - Can it avoid unnecessary two-stage thyroidectomy? - A retrospective cohort study.

BACKGROUND: The objective of this study was to determine if the laryngeal twitch response, when compared to neuromonitoring, can predict postoperative vocal cord function and can thus be used in case of technical failure of the EMG-recording electrode. METHODS: A total of 640 nerves at risk were included in this study based on a prospective protocol. The laryngeal twitch response and the EMG-records were compared with the results of the postoperative laryngoscopy. RESULTS: Of the 640 nerves at risk, 582 showed a normal postoperative vocal cord function. A recurrent laryngeal nerve paralysis (no vocal fold movement) was observed in 39 cases and recurrent laryngeal nerve paresis (reduced vocal cord movement) was diagnosed in 19 cases. The overall negative predictive value (NPV) in final vagus nerve stimulation (V2) was 95.0% for the EMG-records and 94.8% for the laryngeal twitch response. When pareses were excluded, the NPV was 96.8% and 96.6% respectively. The positive predictive value (PPV) of vagus nerve stimulation lies between 51.4% and 57.1% excluding the pareses. It rises to values between 60.0% and 65.1% if they are included. CONCLUSIONS: The laryngeal twitch response and the EMG-records show similar results, and the NPV is good in both. Thus, in case of technical failure or displacement of the EMG-recording electrode, the laryngeal twitch can be used in decision-making for or against a two-stage thyroidectomy.

Comparing the inferior colliculus of young and old gerbils (Meriones unguiculatus) with an emphasis on GABA.

Indicators of an age-dependent down-regulation of GABA (gamma amino butyric acid) have been well-documented in the inferior colliculus (IC) of several rat strains. In the present study, we performed a quantitative light microscopic analysis of GABA-immunostained IC sections to characterize the effect of age on the cross-sectional area of the IC, the number and density of GABAergic cells and the expression of GABA in gerbils. Compared to young gerbils, a significant shrinkage of the IC but no loss of GABAergic cells was found resulting in an increased density of GABAergic cells in old gerbils. The expression of GABA in neurons and the neuropil of the IC did not differ between young and old gerbils. The results in the gerbil differ considerably from age-dependent changes described for the rat IC, showing clear species-specific differences.