Functional neurological disorders (FND) are conditions in which patients experience neurological symptoms without a currently known underlying structural or pathophysiological abnormality in the nervous system. FND are common and were found to be present in up to 16 percent of patients referred to neurology outpatient clinics.1 The diagnosis of FND remains largely clinical although supportive evidence (e.g. for functional tremor) can be demonstrated with electromyographic studies.2 Patients may present with weakness, gait problems, hyperkinetic movements, dysarthria, or a combination of presenting symptoms. Onset of the disorder is often sudden and symptoms are typically variable, distractible, and may be of intermittent nature.3-5 FND are more commonly seen in young females4 and are often believed to be related to an underlying psychological trauma, but it is important to not exclude this diagnosis based on demographics6 and the absence of psychological stress factors. Historically, FND have been felt to be due to conversion of an underlying psychological trauma into physical symptoms (“conversion disorder”), and patients were typically referred for psychiatric care once the diagnosis was established. Diagnostic criteria have recently been revised and the presence of a psychological stress factor is no longer required per DSM-V (Table 1).7 Although no treatment guidelines for FND exist, the value of physical therapy in addition to psychological based treatment has been emphasized in recent years.8
Our patient was a 66-year-old right-handed male initially presenting with pain and intermittent weakness in his legs at age 63. Symptoms occurred episodically and were of fluctuating severity, characterized by the inability to move his legs. Several weeks later, his arms were affected as well. Episodes lasted from minutes to several hours at a time and he would typically lay in a recliner until the episode passed. There was no associated alteration of consciousness or other seizure-like phenomena. About a year later, his speech started to become intermittently slurred, usually for several hours at a time. This could occur independently or with the weakness. He was seen at several outside institutions and underwent extensive diagnostic studies including magnetic resonance imaging of the brain and whole spine and MR-angiography of head and neck. Laboratory studies for blood counts, a comprehensive metabolic panel, thyroid function tests, vitamin B12, folate, copper, ceruloplasmin, glycated hemoglobin, antinuclear antibody, rapid plasma reagin, zinc, protein electrophoresis, sedimentation rate, creatine kinase and angiotensin converting enzyme were normal. Testing for porphyria, an acetycholine receptor antibody panel and cerebrospinal fluid analysis including a paraneoplastic panel were negative. He had a normal 72-hour video-electroencephalogram and normal visual, auditory and somatosensory evoked potentials. His electromyography showed mild left median neuropathy and a chronic left lumbosacral radiculopathy. Although not supported by electrophysiologic studies, he received a diagnosis of antibody-negative myasthenia gravis and was started on treatment with pyridostigmine without benefit for several weeks. He was subsequently diagnosed with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and was empirically treated with eight cycles of intravenous immunoglobulin infusions, which gave him relief for few days at a time. Another neurologist started him on acetazolamide for suspected episodic ataxia with no benefit.
ARTICLE AT A GLANCE
Functional neurologic symptoms are frequently encountered in clinical practice but may commonly be misdiagnosed, especially in elderly patients and in the absence of psychiatric comorbidities or obvious stress factors. In a case report, a 66-year-old gentleman with a functional gait and speech disorder was inappropriately treated for presumed myasthenia gravis and CIDP for over a year despite the absence of typical electromyographic features. Once correctly diagnosed, he was able to regain normal neurologic function with a short-term inpatient rehabilitation program.
The patient sought another opinion at an academic movement disorders center and was given the diagnosis of a FND based on the phenomenology of his spells and intermittent resolution of symptoms. Given the severity of his disorder, he was referred to our center for admission to an inpatient multidisciplinary treatment program. Examination in our clinic showed a pleasant elderly male in a wheelchair with anxious affect. He was fully alert and oriented and had a normal score on the Montreal Cognitive Assessment. Examination of cranial nerves II-XII was unremarkable. His motor strength was 5/5 in all extremities, DTR were symmetric and rated 2+ and sensory examination was normal. He had no tremor or other involuntary movements and no limb ataxia was present. Despite his normal strength testing, he had great difficulties with getting up from a chair and initiating gait. He had straps attached around his thighs and pulled on both straps while walking in order to move his legs, giving his gait a marionette-like appearance (see video on PracticalNeurology.com). During the examination, he developed an unusual spell with severe dysarthria and reported inability to move either arms or legs. However, with appropriate encouragement, he continued to demonstrate full strength on individual muscle testing. Irregular, high amplitude flailing movements were present in both arms. His gait and speech spontaneously returned to baseline after 15 minutes. He had no prior history of weakness or gait difficulties earlier in life and denied a history of seizures, preceding physical trauma, fevers or sick contacts. He denied any psychological stressors preceding the onset of his symptoms. He was a retired car salesman, denied smoking or drug use and had no family history of neurologic disorders. A neuropsychological assessment revealed normal cognitive function and mild depression and anxiety. We agreed with the diagnosis of FND and recommended inpatient admission for rehabilitation. The patient was admitted for a one-week multidisciplinary treatment program based on the principles of motor retraining9 and cognitive behavioral therapy. He improved greatly over the course of the week. In fact, by the third day he had no further episodes of weakness or dysarthria. He has been able to maintain treatment success with home exercises at six-month follow-up.
Our patient presented with typical symptoms of a FND, characterized by paroxysmal weakness and dysarthria with variable and non-congruent findings on examination. Other typical features included the acute onset of symptoms and normal diagnostic imaging and electrophysiologic studies. A recent study demonstrated that the clinical assessment is most decisive in making a diagnosis of FND,10 with the caveat that neurologists need to be familiar with typical signs and symptoms of these disorders. Given the high prevalence of FND in neurologic practice, greater emphasis should be placed on teaching residents and practicing neurologists about diagnosis and management of these conditions. As already mentioned, the current DSM-V criteria (Table 1) do not require the presence of a preceding psychological stress factor for diagnosis of FND. Of note, the latest version of the International Classification of Disease (ICD-11), which is due to be finalized this year, will for the first time include functional neurological disorders within the “neurology” rather than “psychiatry” section.
Our case demonstrates that patients with FND frequently experience a delay in diagnosis, as many practitioners order extensive diagnostic studies and inappropriately consider FND a diagnosis of exclusion. Neurologists without special training in movement disorders may also be hesitant of making a diagnosis of FND in elderly patients and in the absence of apparent psychological trauma. Further complicating factors in the management of FND is the misperception by some practitioners that patients are voluntarily producing their symptoms in order to have secondary gains such as disability benefits, which in our experience is rarely the case.
Left untreated, the prognosis of FND is generally poor and patients often experience a chronic course of the disorder.11 Receiving the correct diagnosis in a timely fashion is important to avoid unnecessary and potentially harmful diagnostic testing and treatments as in our case and facilitate referral for appropriate therapies.12 Despite the delay in diagnosis, our patient was able to recover normal neurologic function with a short inpatient treatment approach. Familiarity with the common phenomenology of FND, patient counseling, and referral to appropriate therapies can lead to very satisfactory treatment outcomes.
The authors are grateful to Dr. Darryl Kaelin and the multidisciplinary rehabilitation team at Frazier Rehab Institute in Louisville, KY, for outstanding treatment of our FND patients.
Kathrin LaFaver, MD is Assistant Professor of Neurology at the University of Louisville School of Medicine.
Tapan Abrol, MD is a resident at the University of Louisville School of Medicine.
For more coverage of functional movement disorders, see article in the March 2017 edition of Practical Neurology®, entitled “’It’s Not In Your Head’: Navigating the Challenges of a Functional Movement Disorder Diagnosis,” by Katie Kompoliti, MD.
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