Eglin Family Medicine Residency, Eglin Air Force Base, FL (Dr. Clemente Fuentes); Abrazo Health Network Family Medicine Residency, Phoenix, AZ (Dr. Bucaj); Defense Health Headquarters, Falls Church, VA (Dr. Wonnum) roselynjan.w.fuentes.mil@mail.mil
The authors reported no potential conflict of interest relevant to this article.
The opinions and assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the US Air Force Medical Department or the US Air Force at large.
The work-up over the next month for Mr. D includes numerous studies, all yielding results that are negative or within normal limits: visual acuity; electrocardiography and an event monitor; laboratory testing (including a complete blood count, comprehensive metabolic panel, thyroid-stimulating hormone, creatine kinase, erythrocyte sedimentation rate, C-reactive protein, vitamin B12, folate, and vitamin D); magnetic resonance imaging of the brain and lumbar spine; lumbar puncture; and electromyography.
The score on the 9-item Patient Health Questionnaire for depression is 4 (severity: “none or minimal”); on the 7-item Generalized Anxiety Disorder scale, 0 (“no anxiety disorder”).
Referral. A neurology work-up of headache, lower extremity weakness, and unsteady gait to address several diagnostic possibilities, including migraine and multiple sclerosis, is within normal limits. A cardiology work-up of palpitations is negative for arrhythmias and other concerning findings.
Mr. D declines psychiatric and psychological evaluations.
Building a differential diagnosisis a formidable task
The differential diagnosis of FND is vast. It includes neurological, physiological, and psychiatric symptoms and disorders; somatization; and malingering (Table 4).6 Any disorder or condition in these areas that is in the differential diagnosis can be precipitated or exacerbated by stress; most, however, do not involve loss of physical function.12 In addition, the diagnosis of an FND does not necessarily exclude an organic disorder.
A patient’s presentation becomes complicated—and more difficult to treat—when functional symptoms and an unrelated underlying or early-stage neurological condition coexist. For example, a patient with epilepsy might also have dissociative seizures atop their organic disorder. Neurological disease is considered a risk factor for an overlying FND—just as the risk of depression or anxiety runs concurrently with other chronic diseases.14
Focus on clinical signs to narrow the differential.A thorough social and medical history and physical examination, as discussed earlier, help narrow the differential diagnosis of organic and medically unexplained disorders. Well-defined imaging or laboratory protocols do not exist to guide physicians to a definitive diagnosis, however.
