Beyond “buzzwords”—updated recommendations for evaluating patients presenting without la belle indifference and diagnosing functional neurological symptom disorder: A case report

Introduction

Functional neurological symptom disorder (FND) is a somatic disorder characterized by an acute onset of one or more sensory or motor symptoms in patients who may present with a recent psychological stressor, a history of trauma, or a phenomenon known as “la belle indifference” (LBI)—a paradoxical absence of psychological distress despite a significant medical condition or its symptoms. ¹ The prevalence of LBI in FND ranges from 0% to 54%, whereas the prevalence of LBI in organic diseases is 0%–60%. ² Reflecting this knowledge, LBI has been removed from the fifth edition of The Diagnostic and Statistical Manual of Mental Disorders (DSM-5). Despite this, LBI continues to be used as a classic sign of FND. This practice has been shown to lead to misdiagnosis and delay of proper management. Keeping FND in the differential diagnosis even when LBI is absent may facilitate better patient care and optimize healthcare spending, as discussed below.

Case description

A 60-year-old female presented to the Emergency Department complaining of severe abdominal pain and a sensation of colostomy obstruction. Shortly after arrival, she suddenly lost the ability to speak and developed rapid, rhythmic mandible movements and numbness of the left upper extremity. Notably, these new-onset symptoms caused the patient significant distress. Pertinent past medical history included metastatic colorectal cancer status postsurgical resection, chemotherapy, and radiation; major depressive disorder with psychotic features; cannabis use disorder; and tobacco use disorder. Urine drug testing was positive for cannabinoids, fentanyl, and opiates (opiates were prescribed upon admission to ED). Review of systems revealed headache, throat pain, and epigastric pain radiating to the chest that worsened with inspiration.

Her speech and mandible dysfunction led to concerns for a dystonic reaction, so she was administered diphenhydramine 25 mg intravenously. After the diphenhydramine failed to improve her symptoms, she was evaluated for a stroke. Her National Institutes of Health Stroke Scale score was 9, but subsequent stroke workup including noncontrast head CT was negative. Neurological examination was remarkable for decreased light touch sensation in the left upper extremity. Hoover’s sign was positive bilaterally. Otorhinolaryngology exam was unremarkable. Electrocardiogram indicated asymptomatic sinus bradycardia with premature atrial contractions. Additional imaging studies including chest radiography, CT angiography of the head, and head MRI were unremarkable. CT angiography of the neck revealed a nonspecific prominence of the soft tissues at the level of the left supraglottic/body junction, similar to a previous exam in 2023. Flexible laryngoscopy was grossly unremarkable, revealing small amounts of edema and swelling near the glottis and hypopharynx without obvious structural abnormality.

After these tests failed to identify the cause of the patient’s symptoms, psychiatry was consulted. It was discovered that the patient had a history of auditory hallucinations and childhood trauma in addition to recent major life stressors. When asked, she endorsed experiencing acute loss of speech in the past, with the most recent episode having occurred 1 week prior to this presentation. At that time, she was involved in a motor vehicle accident—a time she described as “high stress.” Shortly following the collision, she lost her ability to speak. Her speech spontaneously returned after 4 hours. Other similar episodes occurred in 2016 and 2023. Upon physical examination, it was noted that attempting to speak would exacerbate her jaw movements, but the movements would decrease in intensity when she was writing or otherwise distracted. No audible phonation was noted. Despite this, the patient was able to communicate effectively via writing and could follow commands.

Based on the largely unremarkable diagnostic workup in addition to the patient’s history, a working diagnosis of FND was established. To help improve symptoms of FND, exacerbating mood conditions must be addressed. For this, the patient received a one-time dose of hydroxyzine 10 mg for symptoms of anxiety. She also received sertraline 25 mg daily for symptoms of anxiety and depression with plans to increase the dose to 50 mg daily after establishing tolerability. Sertraline was chosen because the patient reported that it previously provided therapeutic benefit following her diagnosis of major depressive disorder several years prior, based on DSM-IV criteria. To aid sleep, melatonin 6 mg was given nightly at bedtime. Propranolol 10 mg three times daily was provided for the rapid jaw movements. All of the patient’s home medications were continued without change.

Throughout her hospital stay, the patient slowly regained the ability to speak. The gradual recovery was abnormal compared to her previous episodes, during which she regained the ability to speak all at once. However, during this episode, her recovery began with regaining only the ability to phonate; she was still unable to control her mandible and mouth. The next day, she was able to say a few words. The following day, she remarked, “I can get words out if I go slowly.” Once her speech returned, the patient felt ready to discharge. Because she originally presented for abdominal pain, she was counseled on appropriate bowel regimen and given recommendations to manage her abdominal pain. For her functional speech disorder, she was advised to follow-up with outpatient psychiatric services to explore anger and stress management strategies. At her outpatient follow-up appointment 3 days postdischarge, the patient’s speech was clear and coherent, and her mood and affect were appropriate.

Discussion

Although current literature on LBI in FND is somewhat limited, it suggests that this phenomenon may not be as sensitive for FND as previously believed. In fact, research indicates that LBI may only present in a minority of FND cases. One systematic review found the median frequency of LBI in patients with FND symptoms was 21%, ranging from 0% to 54%. ³ Another study reported an even lower rate, stating that LBI was present in only 3% of patients with FND, calling into question its reliability as a diagnostic criterion. ⁴ Beyond its limited prevalence, over-reliance on LBI can lead to diagnostic errors. For example, cases of progressive supranuclear palsy and fibrocartilaginous embolism have been initially misdiagnosed as FND due to the presence of LBI, which were later understood to be secondary to organic causes.^5,6 Additionally, LBI has been demonstrated to present in cases of stroke with right-sided hemiparesis, neuropathic pain secondary to diabetic neuropathy, and cardiac dyspnea secondary to chronic heart failure. ⁷ The variability in how LBI presents in FND, as well as in other diseases and disorders (range 0%–60%), underscores the importance of comprehensive diagnostic assessments that do not significantly depend on the presence or absence of this phenomenon. ² Instead, diagnosis should be based on a combination of physical exam findings and thorough patient history. The updates in the DSM-5 regarding diagnostic criteria for FND emphasize that it is no longer considered a diagnosis of exclusion. A positive diagnosis can be made if there is presence of a motor or sensory symptom causing distress or difficulty for the patient and positive physical signs of internal inconsistency or incongruity with recognized disease. Essential elements of history collection include a complete list of the patient’s physical symptoms and a detailed description of the patient’s day-to-day function. Questions regarding onset may include whether there was a physical injury, panic attack, viral illness, or other potential trigger. Identifying a recent psychological stressor or past traumatic event is unnecessary for diagnosis of FND, as they are not present in many patients with FND. Duration and characterization of symptoms should be discussed, as symptoms related to FND will usually temporarily improve or be representative of a clinical phenotype typical of FND.^8,9 Prioritizing the history collection and physical examination in this manner may help clinicians more readily narrow down their differential diagnosis and determine which, if any, potential organic causes of their patient’s presentation require more thorough diagnostic evaluation. This will ultimately facilitate more efficient use of healthcare resources, thus decreasing healthcare spending while increasing diagnostic accuracy.

Several questions remain regarding how the misconceptions surrounding the evaluation and diagnosis of FND impact patient care and healthcare spending. How often does the reliance on LBI as a diagnostic indicator lead to an incorrect diagnosis? Have clinicians updated their methods for evaluating motor and sensory symptoms now that FND is no longer considered a diagnosis of exclusion? If evaluation practices have not changed, does this lead to an increase in healthcare spending or a delay in appropriate management? Answering these questions could significantly contribute to the growing body of evidence regarding the importance of staying up to date on diagnostic criteria and practice recommendations not only for the evaluation and management of patients with FND, but for all patients.