Table 1:

Examples of positive diagnostic signs of functional neurologic disorder

FND subtype	Example of positive diagnostic signs^*
Functional tremors	Entrainment: When copying rhythmic movements with opposite hand, the tremor in the affected limb stops or is entrained to the same rhythm Distractable: Abnormal movement stops when patient is focused on a different task
Functional weakness	Inconsistent or “give-way” weakness (initially strong and then sudden loss of resistance) on power testing Hoover sign: Ask the patient to voluntarily extend the hip of the weak leg and assess strength (if patient lying down, the examiner’s hand is placed under the heel). Then ask the patient to flex the healthy hip against resistance and again assess the strength of hip extension of the weak leg (this time it is involuntarily being extended). Compare voluntary to involuntary hip extension strength and if the latter is notably stronger, Hoover sign is positive
Functional seizures	Long-duration waxing and waning episodes that may be accompanied by forced eye closure, tearfulness, side-to-side head-shaking or bilateral limb jerking with preserved consciousness

Note: FND = functional neurologic disorder.
↵* Included examples of FND-positive diagnostic signs focus on motor subtypes relevant to our patient. For a more detailed list of symptom subtypes and diagnostic signs, see Aybek and Perez’s recent review on this topic.1