Thermography in complementary assessments of head and neck muscles: A scoping review

Infrared thermography has the potential to help assess human head and neck muscles, as thermal variation measurements due to muscle imbalance can contribute to the evaluation and therapeutic follow-up of various clinical conditions in the field of health.

This study investigated, with a scoping review, the use of infrared thermography in complementary assessments of human head and neck muscles to determine the extent of research on the topic, what methodologies are used in thermal assessment and thermographic analysis, what regions are assessed, and what results are expected in thermography.

LILACS, MEDLINE, SciELO, and Web of Science were the databases searched to identify articles published on the topic, with no restriction of language or time of publication. Descriptive, analytical, and experimental observational studies on the assessment of the human head and neck muscle surface temperature with infrared thermography were included. Case studies, case series, methodological accuracy, literature review, animal studies, studies that assessed patients with head and neck cancer, and studies that did not assess head and neck muscle temperature with thermography were excluded. The articles were analysed with a protocol developed by the authors, with data on author, year, country, type of study, sample characterisation, muscles assessed, outcomes investigated, thermal assessment methodology, thermographic analysis methodology and thermography measurements.

This review identified and analysed 27 articles. The studies assessed thermal distribution in normal individuals and those with pathologies related to hyper- and hypofunctional head and neck muscle conditions for diagnosis or therapeutic follow-up. The masseter, temporal, digastric, anterior cervical region, orbicularis oris, frontalis, buccinator, suprahyoid, trapezius, sternocleidomastoid and levator scapulae muscles were assessed. Quantitative analyses with area selection tool predominated, considering absolute temperatures and temperature differences. The studies investigated temperature and its relationship with myogenic pain, quantitative assessment of muscle parameters and blood flow velocity. The mean temperature ranged from 32.97°C (±2.21) to 34.90°C, and hyper-radiant and/or asymmetric regions were observed in hyperfunctional conditions and normal subjects after muscle activation.

Thermography is used in complementary assessments of head and neck muscles, identifying hyper-radiant regions and thermal asymmetry related to muscle tension and activation state. Papers are limited to specific clinical conditions and few muscle groups, besides having great methodological variability.