Ultrasound is an established clinical assessment modality with which we may be familiar, perhaps from obstetrics or in the assessment of the integrity of the muscle tissue in neuromuscular disease. However, ultrasound of the head and neck is an interesting and emerging area of consideration for Speech and Language Therapists working within respiratory, voice and swallowing services.
What is ultrasound?
Ultrasound uses high-frequency sound waves that transmit through the body and interact with tissue interfaces. The sound waves are emitted and received from a small, hand-held probe moved in contact with and over the skin. The sound waves reflect or refract off the tissue interfaces and generate the images that can be seen on a monitor and recorded.
Ultrasound waves cannot pass through dense structures, for example in the head and neck structures such as the hyoid bone and thyroid cartilage, so there is a loss of visual information. So, on the images, tissues are grey and the denser the tissue, the brighter or whiter it will be.
Ultrasound is already used to monitor patients in head and neck services, for example for checking for lumps in the neck. After radiotherapy it can be more challenging to obtain useful images because of the fibrosis making it more difficult for the sound waves to penetrate.
An ultrasound scan of the head and neck is usually non-invasive and there is no radiation exposure.
Will ultrasound become an important addition to our assessment tools?
It is early days. Current opinion is that ultrasound is not a replacement for video-fluoroscopy (modified barium swallow), FEES assessments or laryngeal endoscopy, which remain the gold standard diagnostic assessments.
At the moment ultrasound is considered to be a supplementary or an additional tool which provides an added dimension – further information about any changes to or the integrity of the deep structures important for respiration, voice and swallowing.
However, ultrasound is already being used by some clinicians to check for movement disorders of the vocal folds after thyroid surgery.
Ultrasound may have the potential to speed up the diagnostic pathway for inducible laryngeal obstruction (ILO) if the presentation of ILO can be reliably described and measured using ultrasound, and if standardised protocols are developed.
Teams around the world are collaborating to further understand the utility, feasibility, and reliability of ultrasound for speech and language therapy practice and sharing their findings regarding its clinical application. How accessible is ultrasound for our patients?
Ultrasound has become more portable over recent years as the technology has developed. It is available in a range of clinical areas including community locations which may be more accessible for patients who live far from their specialist centre or who present out of clinic hours, for example with exacerbation of symptoms in ILO.
Decontamination of the monitor and the probes is straightforward and, as a non-invasive and non-aerosol generating procedure (AGP) in head and neck, ultrasound is being considered as a useful adjunct to or even a proxy for a screening assessment during the pandemic.
Collaboration is key.
We had the pleasure of chatting with a radiographer and two speech and language therapists (see below) about their experiences of using ultrasound. They have been working to identify the structures of the head and neck important for respiration and relevant to voice and swallowing disorders and weighing the evidence for the application of ultrasound to their clinical practice.
For them, finding local champions for ultrasound and developing networks have been key factors in understanding this modality in the context of voice, respiratory and swallowing disorders. They began with exploring images together, ring-fencing time to explore the literature and developing networks with colleagues in the UK and across the world.
All practices are different, and if you are interested in exploring this further for yourself remember that your local ultrasound champion may be a physiotherapist, a doctor, a nurse, or a radiographer, so cast your net wide!
Thanks for your interest in this topic, please do send us your feedback as we are keen to hear your opinions and any updates from your own practice.
Keep safe and in touch,
Fiona and Suzanne You can find us at www.svsassociates.co.uk and @_svs_associates Information from Episode 10 of SVS PodChats was included in this article.
Thank you to our guests:
Jodi Allen, Senior Speech and Language Therapist at The National Hospital for Neurology and Neurosurgery and NIHR Pre-Academic Fellow @jodiAllenSLT
Claire Slinger, Consultant Respiratory Speech and Language Therapist at the Royal Preston Hospital @claire_slinger
Sally Richmond, Consultant Head and Neck Radiographer at University College London Hospitals @SallyRi26954475
References:
The link to the laryngeal ultrasound paper written by the two radiologists at UCH: https://pubs.rsna.org/doi/10.1148/rg.2020190160
Recent reviews in swallowing & laryngeal ultrasound :
In Press: Utility of Ultrasound in the Assessment of Swallowing & Laryngeal Function: A Rapid Review and Critical Appraisal of the Literature
Journal: International Journal of Language & Communication Disorders
