Hoover's Test for Functional Neurological Weakness
Hoover's test is a bedside clinical examination used to diagnose functional (non-organic) weakness of the lower limb, and a positive result supports the diagnosis of functional neurological disorder (FND).
What is the Test?
Hoover's test actually consists of two complementary subtests performed with the patient supine 1:
Testing the "weak" leg: Place your hand under the heel of the reportedly weak leg and ask the patient to lift that leg against resistance. In functional weakness, you'll feel little to no downward pressure, but in organic weakness, you'll feel normal synergistic downward pressure.
Testing the "normal" leg: Place your hand under the heel of the reportedly weak leg and ask the patient to lift the opposite (normal) leg against resistance. In functional weakness, you'll now feel strong downward pressure under the "weak" leg (involuntary hip extension), demonstrating that the weakness is not organic.
The test exploits the principle of synergistic contraction—when flexing one hip, the contralateral hip normally extends involuntarily 2. In functional weakness, voluntary hip extension is absent but involuntary hip extension during contralateral hip flexion remains intact 3.
What Does a Positive Result Mean?
A positive Hoover's sign indicates functional neurological disorder (FND) with functional weakness 4. This is explicitly recognized in current FND guidelines as one of the "positive clinical signs" used by neurologists to diagnose FND 4.
Diagnostic Performance
This means when positive, the test is highly reliable for functional weakness, but a negative test does not rule it out.
Critical Diagnostic Context
FND is diagnosed using positive clinical signs like Hoover's sign and is NOT a diagnosis of exclusion 4. The diagnosis should be made affirmatively based on the presence of these signs, not simply because other conditions have been ruled out. FND can coexist with other neurological conditions 4.
Important Caveats and Pitfalls
Recent evidence suggests Hoover's sign may be more nuanced: It can occur in people with pain, other functional disorders, and even FND without weakness 5. It may reflect altered agency and sensory processing rather than purely "functional weakness" 5.
COPD confusion: Be aware that "Hoover's sign" in pulmonary medicine refers to something completely different—paradoxical inspiratory rib motion in severe COPD 6. This is unrelated to the neurological test.
Technique matters: Avoid having the patient voluntarily press down with the unlifted leg before testing, as this directs attention to that leg and may confound results 1. A modified approach using a "break test" maneuver may improve objectivity 1.
Quantitative approaches exist: Using weighing scales to measure pressure forces can provide objective data, with a Hoover's index >1.4 suggesting functional weakness 7.
Clinical Application
When you identify a positive Hoover's sign, use it as part of a comprehensive explanation to the patient that FND is a real, disabling condition diagnosed through specific neurological signs, not a diagnosis made because "nothing else was found" 4. This positive framing is essential for therapeutic engagement and rehabilitation success.