Efficiency of intraoperative neuromonitoring on voice outcomes after thyroid surgery

Application of patch stimulator for intraoperative neuromonitoring during thyroid surgery: maximizing surgeon's convenience

Background

Intraoperative neuromonitoring (IONM) is frequently used in thyroid surgery to reduce recurrent laryngeal nerve (RLN) injury by providing the surgeon with real-time feedback on nerve stimulation during dissection. We applied a disposable adhesive patch electrode to a dissecting instrument to transfer electrical stimulation to the dissecting instrument for IONM during thyroid surgery. This study aimed to evaluate the feasibility of using the patch stimulator approach for IONM during thyroid surgery.

Methods

We reviewed the medical records of patients who underwent thyroidectomy using both conventional stimulator and adhesive patch stimulator for IONM. The electromyography (EMG) amplitudes of the vagal and the RLNs before (V1, R1) and after thyroid resection (V2, R2) were alternatively checked with each type of stimulator at the same location of each nerve.

Results

Fifteen consecutive patients (4 males, 11 females) were included in this analysis, and a total of 38 nerves (19 vagus nerves and 19 RLNs) were evaluated. No statistically significant differences were seen in the mean amplitudes evoked by the patch stimulator and the conventional probe stimulator for the V1 signal (825.5±394.6 vs. 821.8±360.9 µV, P=0.954), R1 signal (1,044.8±471.2 vs. 1,039.2±507.4 µV, P=0.898), R2 signal (1,037.8±495.0 vs. 938.2±415.8 µV, P=0.948), or V2 signal (812.5±391.9 vs. 787.3±355.7 µV, P=0.975).

Conclusions

The patch stimulator was safely and effectively used for IONM during thyroid surgery and provided similar nerve monitoring responses as the conventional stimulator. This approach may be used to enhance the surgeon's convenience during thyroid surgery.

Development and Validation of the Thyroidectomy-Related Voice and Symptom Questionnaire (TVSQ)

OBJECTIVES

Common symptoms after thyroidectomy include voice change and throat and neck discomfort. But no common questionnaire has been developed. This study was performed to evaluate the reliability and validity of the Thyroidectomy-related Voice and Symptom Questionnaire (TVSQ).

METHODS

Fourty items of the TVSQ were divided into 20 items related to the "voice change" and "throat and neck discomfort" subcategories, using item generation. Through a reduction process, 20 items were removed and 20 items were used. For the patients after thyroidectomy, we evaluated the reliability and validity of each of the 20 items through item discrimination, test-retest reliability, concurrent validity, and external validity by comparing normal group and laryngeal disease patients. Also, the patients were compared before as well as 2 and 4 weeks after thyroidectomy.

RESULTS

Item discrimination assessment showed a significant correlation between TVSQ total score and both the TVSQ "voice change" score (r = 0.908**) and TVSQ "throat and neck discomfort" score (r = 0.862**). Test-retest reliability assessment showed a significant correlation between TVSQ total scores at 2 and 4 weeks postoperatively (r = 0.764**). Concurrent validity assessment revealed that the TVSQ showed high correlations with other voice questionnaires (Voice Handicap Index, Reflux Finding Index, and Vocal Track Discomfort Scale; r = 0.538**-0.830**). External validity assessment revealed that the TVSQ was suitable for patients after thyroidectomy (P < 0.000**).

CONCLUSIONS

Validity and reliability tests revealed that the TVSQ was suitable for assessment of the subjective feelings of patients with voice change and throat and neck discomfort after thyroidectomy.

Feasibility of Brachial Plexus Schwannoma Enucleation With Intraoperative Neuromonitoring

Objectives

To evaluate the feasibility of brachial plexus schwannoma enucleation under intraoperative neuromonitoring.

Methods

Five patients who were treated for brachial plexus schwannoma under intraoperative neuromonitoring from 2008 to 2018 were included in this retrospective review. Neuromonitoring was performed with a 100-μV event threshold of the neuromonitoring system (NIM-2 or 3) at the deltoid, biceps brachii, triceps brachii, and brachioradialis muscles. Patient characteristics, tumor size and location, intraoperative neuromonitoring findings, and postoperative function were evaluated.

Results

The intraoperative neuromonitoring findings were in accordance with the preoperative assessment of the included nerve root. Three patients had no postoperative morbidity, one patient had temporary paresthesia of the forearm for 2 months, and one patient mild loss of grip strength for 1 month.

Conclusion

Intraoperative neuromonitoring of the arm and forearm muscles during enucleation of brachial plexus schwannoma promoted confident and successful surgery with minimal postoperative morbidity.