The threshold tracking nerve conduction study technique: Experience of clinical users unfamiliar with a research-grade neuronal excitability system.

Objective: To 1) explore if clinical electrophysiologists with different degrees of experience performing standard nerve conduction studies could run a threshold tracking nerve conduction study (TTNCS) protocol and 2) learn how clinical users view a research-grade TTNCSs neuronal excitability system. Methods: Five clinical electrophysiologists conducted a TTNCS session using QTracS and then completed a questionnaire describing their impressions. Results: All of the electrophysiologists completed the QTracS protocol on an initial attempt. Perceived strengths comprised the ease of preparatory steps and quick protocol speed. Identified drawbacks included an unwieldly user-interface. The electrophysiologists indicated that knowledge of TTNCS principles and applications would be critical for incorporation of the method into clinical use. Conclusions: This pilot study suggests that clinical electrophysiologists can carry out TTNCSs with a research-grade system. The development of a more user-friendly program, along with dedicated education and training, could lead to wider application of the TTNCS technique. Significance: Considered together with clinical presentation and other biomarkers, increased use of TTNCSs could provide improved assessment of neuromuscular disease and treatment response.

Quantitative ultrasound of the tongue: Echo intensity is a potential biomarker of bulbar dysfunction in amyotrophic lateral sclerosis.

OBJECTIVES: To learn if quantitative ultrasound (QUS) distinguishes the tongues of healthy participants and amyotrophic lateral sclerosis (ALS) patients by echo intensity (EI) and to evaluate if EI correlates with measures of bulbar function. METHODS: Ultrasound was performed along the midline of the anterior tongue surface in 16 ALS patients and 16 age-matched controls using a linear hockey stick 16-7 MHz transducer. A region of interest was manually drawn and then EI was determined for the upper 1/3 of the muscle. For patients, the ALS functional rating scale - revised (ALSFRS-R) was used to calculate bulbar sub-scores and the Iowa Oral Performance Instrument (IOPI) was used to measure tongue strength. RESULTS: EI was significantly higher in ALS patients than in healthy participants (49.8 versus 37.8 arbitrary units, p < 0.01). In the patient group, EI was negatively correlated with ALSFRS-R bulbar sub-score (RS = -0.65, p < 0.01). An inverse correlation between EI and tongue strength did not reach significance (RS = -0.34, p = 0.28). CONCLUSIONS: This study suggests that EI can differentiate healthy from diseased tongue muscle, and correlates with a standard functional measure in ALS patients. SIGNIFICANCE: Tongue EI may represent a novel biomarker for bulbar dysfunction in ALS.