By Jennifer Langsdorf, MD
Assistant Professor of Neurology, Peripheral Neuropathy Center, Weill Cornell Medical College
SYNOPSIS: A stepwise diagnostic algorithm was developed to identify potentially treatable idiopathic inflammatory myopathies in patients presenting with isolated unexplained dysphagia.
SOURCE: Labeit B, Grond T, Beule AG, et al. Detecting myositis as a cause of unexplained dysphagia: Proposal for a diagnostic algorithm. Eur J Neurol 2022;29:1165-1173.
Swallowing disorders can occur in many neurological disorders, including stroke, myasthenia gravis, amyotrophic lateral sclerosis, and many other disorders of the central nervous system, peripheral nerves, and muscles. Impaired swallowing causes significant morbidity and mortality because of the risk of aspiration pneumonia and respiratory failure. Early identification and treatment of swallowing disorders can greatly improve patient outcomes and quality of life.
When dysphagia is the sole or presenting symptom, identification of the cause of swallowing difficulty can be difficult. Dysphagia occurs frequently in idiopathic inflammatory myopathy (IIM) and is considered a diagnostic hallmark. The muscles of the oropharynx and upper esophagus are skeletal muscle and can be affected early in IIM. If only these small muscles are affected in isolation and the limbs are asymptomatic, creatine kinase (CK) blood levels may remain normal, making the diagnosis more challenging. Early diagnosis of focal myositis in the swallowing muscles can lead to earlier initiation of treatment and may even prevent the development of systemic disease.
This retrospective study presents the results of using a new stepwise diagnostic algorithm for patients with unexplained dysphagia as the initial or sole symptom. The algorithm was developed in 2016 at the Center for Neurogenic Dysphagia and was offered to all patients with unexplained dysphagia who presented between December 2016 and December 2020.
The first step in the algorithm is objective swallowing analysis with instrumental assessment for the presence of pharyngeal dysphagia. The two main methods used are flexible endoscopic evaluation of swallowing (FEES) and videofluoroscopic swallowing studies (VFSS). Objective findings, such as pharyngeal residue, reduced pharyngeal contractility, and esophageal hypomotility, among others, were considered IIM-compatible findings. If found, the next step in the algorithm is to exclude other neurologic disorders using the clinical neurologic exam, magnetic resonance imaging (MRI) of the brain, lumbar puncture, and edrophonium test for myasthenia gravis.
In this study, 72 patients presented with unexplained dysphagia potentially compatible with IIM. The patients were 79% male, with a mean age of 69 years and an average disease duration of 3.8 years. After instrumental assessment and exclusion of other neurologic disorders as noted earlier, 45 potential myositis patients remained.
The next step in the algorithm is to focus on testing specifically for detection of myositis. Testing includes blood tests for both muscle breakdown (CK, lactate dehydrogenase, aspartate aminotransferase, and alanine transaminase) and commonly tested myositis-associated antibodies. In addition, whole-body MRI and electromyography (EMG) are performed to look for additional evidence of systemic myositis and to identify potential affected sites for muscle biopsy. In this study, this testing resulted in only one diagnosis of IIM, which was made on the basis of positive Jo-1 antibodies.
For the remaining dysphagia patients with diagnostic uncertainty, muscle biopsy is recommended as the final diagnostic step. Thirty-three patients in this study underwent muscle biopsy. If no other muscles on EMG or whole-body MRI showed abnormality, then a cricopharyngeal muscle biopsy was performed under general anesthesia. This procedure was performed on 12 patients. If limb or other muscles showed evidence of myositis, these muscles were preferentially biopsied. This was done for 21 patients.
Of the 33 patients who had muscle biopsies, 18 were diagnosed with definitive or probable IIM. These 18 patients received immunotherapy. Ten of these patients had follow-up endoscopic evaluation (FEES), and nine of them stabilized or improved.
COMMENTARY
This stepwise algorithm helps identify potentially treatable IIM in patients presenting with isolated dysphagia. In this study sample, a valid IIM diagnosis was made in 26% of the patients with an IIM-compatible dysphagia pattern on instrumental swallowing assessment. This is an unexpectedly high percentage given the rarity of the condition and the level of diagnostic difficulty when myositis is limited predominantly to the oropharyngeal muscles.
