Applied Evidence

Functional neurological disorder: A practical guide to an elusive Dx

Author and Disclosure Information

 

References

Mr. D has an antalgic gait with significant swaying (without falling); bent posture; and unsteadiness that requires a cane. However, he is able to get up and off the exam table without assistance, and to propel himself, by rolling a chair forward and backward, without difficulty.

Conducting a diagnostic examination

Taking the history. Certain clues can aid in the diagnosis of FND (TABLE 1).15 For example, the patient might have been seen in multiple specialty practices for a multitude of vague symptoms indicative of potentially related conditions (eg, chronic fatigue, allergies and sensitivities, fibromyalgia, and other chronic pain). The history might include repeated surgeries to investigate those symptoms (eg, laparoscopy, or hysterectomy at an early age). Taking time and care to explore all clinical clues, patient reports, and collateral data are therefore key to making an accurate diagnosis.

Signs, symptoms, and other findings of FND

A coexisting psychiatric diagnosis might be associated with distress from the presenting functional neurological symptoms—not linked to the FND diagnosis itself.

Note any discrepancies between the severity of reported symptoms and functional ability. A technique that can help elucidate a complex or ambiguous medical presentation is to ask the patient to list all their symptoms at the beginning of the interview. This has threefold benefit: You get a broad picture of the problem; the patient is unburdened of their concerns and experiences your validation; and a long list of symptoms can be an early clue to a diagnosis of FND.

The physical examination in suspected FND

Other helpful questions to determine the impact of symptoms on the patient’s well-­being include inquiries about16:

  • functional impairment
  • onset and course of symptoms
  • potential causal or correlating events
  • dissociative episodes
  • previous diagnoses and treatments
  • the patient’s perceptions of, and emotional response to, their illness
  • a history of abuse.
The physical examination in suspected FND

The physical examination to determine the presence of FND varies, depending on the functional area of impact (eg, motor, neurological, sensory, speech and swallowing). Pay particular attention to presenting signs and clues, and balance them with the patient’s report (or lack of report). Endeavor to demonstrate positive functional signs, such as a positive Hoover test, which relies on the principle of synergistic muscle contraction. You might see evidence of inconsistency, such as weakness or a change in gait, under observation, that seemingly resolves when the patient is getting on and off the exam table.16Table 215-24 describes areas affected by FND, characteristics of the disorder, and related diagnostic examinations.

The physical examination in suspected FND

Table 315,18,19 reviews validated special exams that can aid in making the diagnosis. Additional special tests are discussed in the literature.15-24 These tests can be helpful in narrowing the differential diagnosis but have not been validated and should be used with caution.

Specialized tests for FND

Some clinical signs associated with FND might be affected by other factors, including socioeconomic status, limited access to health care, low health literacy, poor communication skills, and physician bias. Keep these factors in mind during the visit, to avoid contributing further to health disparities among groups of patients affected by these problems.

Specialized tests for FND

Continue to: CASE

Pages

Recommended Reading

Child ‘Mis’behavior – What’s ‘mis’ing?
MDedge Family Medicine
The importance of family acceptance for LGBTQ youth
MDedge Family Medicine
Emerging research shows link between suicidality, ‘high-potency’ cannabis products
MDedge Family Medicine
One in 10 family docs with burnout consider quitting medicine
MDedge Family Medicine
Tips offered for treating co-occurring ADHD and SUDs
MDedge Family Medicine
Screening tool may help better predict suicide attempts in adolescents
MDedge Family Medicine
Ob.gyns. report high burnout prior to pandemic
MDedge Family Medicine
Inflammatory immune findings likely in acute schizophrenia, MDD, bipolar
MDedge Family Medicine
Heroes: Nurses’ sacrifice in the age of COVID-19
MDedge Family Medicine
PTSD prevalent in survivors of severe COVID-19
MDedge Family Medicine