A thorough physical and neurological exam should be conducted to exclude serious medical and neurological disorders. Neurological disorders that need to be ruled out include multiple sclerosis, stroke, Guillain-Barré syndrome, myopathies, polymyositis, and myasthenia gravis. Depending on the presentation, a focused neurological exam should be performed. Described below are some tests for motor symptoms with high sensitivity and specificity for CD. A full range of neurological exams for motor, sensory, and gait are summarized by Oneal and Baslet.[19]

Hoover's sign (63% Sensitivity & 100% specificity): This test is commonly used to separate organic from the nonorganic cause of the weakness or paralysis. An examiner's hand is placed below the heel of the affected leg, and the patient is asked to flex the hip of the normal leg against resistance. In organic disorders, there should not be any pressure on the examiner's hand on the affected side, while pressure is felt in patients with FNSD/CD.[20]

Variable Strength (63% sensitivity and 97% specificity): The weakness is inconsistent with variable force at different locations.

Inconsistencies in the exam (13% sensitivity and 98% specificity): Individuals have an inconsistent presentation of signs and symptoms when performing the voluntary activity and when they are being examined. 

Co-contraction (17% sensitivity and100% specificity): When asked to flex the elbow, there is a contraction of both triceps and biceps.[21]

For tremors, distraction affecting the tremor (92% sensitivity and 94% specificity), tremor variability (22% sensitivity and 92% specificity), and tremor entertainment ( (91% sensitivity and 92% specificity) are commonly used.[22]

EEG and video-EEG should be ordered to rule out epileptic seizures. MRI is essential to rule out neurological disorders like multiple sclerosis or stroke. Labwork should be done to rule out Guillain-Barré syndrome, myopathies, polymyositis, and myasthenia gravis. Some patients with PNES may also have epileptogenic seizures [23]. The approximate incidence of epileptic seizures in patients with PNES is 10% [24]. In some cultures, seizure-like episodes are common during cultural rituals. Therefore, providers must carefully explore the religious and cultural association with symptoms in these individuals.

Treatment of FNSD/CD poses a significant challenge due to the lack of empirical studies and RCTs.[16] A comprehensive treatment approach involving multiple specialties - primary care providers (PCPs), psychiatrists, neurologists, and psychologists is usually needed. The three P's approach -identifying predisposing factors, precipitating stressors, and perpetuating factors are suggested in the literature.[25]

Cognitive-behavioral therapy (CBT) is identified as an effective treatment for SSD.[26][27] In a pilot study of 16 PNES patients treated with CBT, a significant reduction of symptoms was seen at a 6-month follow up.[28] In a study looking at the effectiveness of pharmacology, 7 out of 10 patients with conversion disorder showed improvement in motor symptoms with antidepressants.[29] Though there are several treatment strategies suggested, there is no effective evidence-based treatment for FNSD/CD.[27] Providers should focus on the effective treatment of comorbidities and the management of stressors and psychological trauma.

FNSD/CD can be present in patients with physical illness. Patients with epileptogenic seizures may also have concurrent PNES.[23] Patients with significant and life-threatening physical illness may also present with dissociative symptoms and conversion. However, patients with la belle indifference do not appear to be distressed by their symptoms. FNSD/CD is frequently seen in patients with multiple psychiatric comorbidities like depression, anxiety, PTSD, and personality disorders. Multiple sclerosis, stroke, Guillain-Barré syndrome, myopathies, polymyositis, and myasthenia gravis should be considered in the differential.

Prognosis of FNSD/CD depends on the onset and duration of the symptoms. Acute onset and short duration with an identifiable stressor generally have a good prognosis. For a quarter of patients the symptoms of conversion resolve within weeks.[16] In a longitudinal study of patients with psychogenic movement disorders, patients with psychiatric comorbidities have prolonged duration of symptoms.[30]

According to a systematic review by Stone et al., there is only a 4% chance of misdiagnosis of FNSD/CD.[31] However, there remains a risk that a true neurological or medical etiology may be missed, and treatment is delayed in these cases. Hence an immediate referral by PCP for comprehensive screening and assessment by psychiatry and neurology is essential to arrive at an accurate diagnosis in a reasonable amount of time.

Primary teams should consult neurology, psychology, and psychiatry for appropriate diagnosis, referral, and treatment of la belle indifference and FNSD/CD.

A multidisciplinary treatment approach is needed to diagnose and treat FNSD/CD. Engaging patients is critical for positive treatment outcomes. The first step towards patient engagement is the patient’s acceptance of their diagnosis. Educating the patient on their physical symptoms and how the diagnosis of FNSD/CD was made should be explained in a manner that the patient understands.[32]

A comprehensive screening and assessment by a multidisciplinary treatment team, including primary care providers, neurology, and psychiatry, are needed for the diagnosis and treatment of FNSD/CD. Active collaboration and agreement regarding the diagnosis across specialties involved in the care of the patient are required to prevent unnecessary consultations, testing, multiple hospital visits, and health care utilization. Patients should be educated on their presenting symptoms, and efforts should be made to engage the patient in treatment. Treatment outcomes are generally worse if the patient does not have buy-in in their diagnosis of FNSD/CD, or do not engage in treatment.[33]