Negative results and positive signs point to the Dx
Conversion disorder is not a diagnosis of exclusion. Diagnosis requires detailed history taking and a thorough neurologic exam. Laboratory testing and neuroimaging are also important, and results will have to be negative to support the diagnosis.
Conversion disorder is not a diagnosis of exclusion; diagnosis requires detailed history taking and a thorough neurologic exam.
Neurologic deficits with conversion disorder do not follow a known neurologic insult.14 There are many tests that can be used to distinguish functional symptoms vs organic symptoms. Two of the most well-known tests are the Hoover sign and the abductor sign, which will be positive in conversion disorder. Both can be performed easily in an outpatient setting.
The Hoover sign is considered positive when there is weakness of voluntary hip extension in the presence of normal involuntary hip extension during contralateral hip flexion against resistance. According to a meta-analysis of multiple studies of patients with conversion disorder, the overall estimated sensitivity of this test is 94% and the specificity, 99%.15
The abductor sign follows the same principle as the Hoover sign: When the patient abducts the nonparetic leg, both the nonparetic and “paretic” leg are strong. When the patient abducts just the “paretic” leg, both legs become weak.16
Other symptom evaluations.For patients who have functional seizures, video electroencephalography is helpful to distinguish functional seizures from “true” seizures.17,18 In conversion disorder, functional dysarthria normally resembles a stutter or speech that is extremely slow with long hesitations that are hard to interrupt.18 Dysphonia and functional dysphagia are also very common functional symptoms. Usually after extensive work-up, no organic cause of the patient’s symptoms is ever found.18
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