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Play today's Psychology caseFive progressive clues
These are the case findings in their original reveal order, moving from the broader presentation to the most discriminating evidence.
Clue 1
A 34-year-old woman comes in leaning hard on her sister’s arm. Three weeks ago, over the course of a single evening, her right leg went weak, and she has not walked unaided since. Three days before that she had been in a car crash she walked away from without a scratch.
Clue 2
She has been through this once already. Another hospital scanned her, told her the pictures were clear and that there was nothing wrong, and sent her home — which she heard as being told she was making it up. Ask her to walk a few steps now and the right knee gives way again and again, sharply and without warning. She catches herself every time. She has not once hit the floor.
Clue 3
On the couch the leg behaves strangely. Push against it lightly and it holds for a second, then collapses all at once instead of fading away. Ask her to move it and the muscles on both sides of the joint tighten against each other. The weak territory belongs to no nerve root, no peripheral nerve, and no spinal level. And on formal testing she cannot lift that leg a centimetre off the couch — yet a minute later she turns to reach for her shoes and the same leg swings up on its own.
Clue 4
One manoeuvre settles it. The examiner slides a hand under her right heel and asks her to press down: nothing comes. Hand still in place, she is asked instead to lift the good left leg against resistance — and the right heel drives down hard into the palm, exactly the movement she could not produce a moment earlier. This is what the criteria mean by clinical findings that show incompatibility with recognised neurological disease. The diagnosis is made by a positive sign, not by a normal scan.
Clue 5
The rest of the workup returns exactly as expected and proves nothing on its own. Magnetic resonance imaging: no structural lesion, no demyelination. Electroencephalography: no paroxysmal or epileptiform activity. Cognitive screening: normal across every domain, no neurocognitive disorder. All of it together only confirms that nothing else explains her better. None of it is what made the diagnosis. The heel did.
Diagnosis
Conversion Disorder
Why the diagnosis fits
This is conversion disorder — functional neurological symptom disorder — and how it is diagnosed has changed. The criteria are: one or more symptoms of altered voluntary motor or sensory function; clinical findings that provide evidence of incompatibility between the symptom and recognised neurological or medical conditions; the picture is not better explained by another medical or mental disorder; and the symptom or deficit causes clinically significant distress or impairment. Note what is no longer there. The current criteria removed the requirement to prove psychological factors, and the emphasis moved to positive diagnostic signs rather than to ruling organic disease out one test at a time. That is why the heel manoeuvre is the centre of this case: with a hand under the weak heel, asking her to raise the good leg against resistance produces firm downward pressure through the very heel she could not press down to order. That is the Hoover sign. Around it sit the other positive features — collapsing give-way weakness, co-contraction of agonist and antagonist, a distribution that fits no root, nerve, or spinal level, a knee that buckles without her ever hitting the floor, and a leg that moves freely when she is not being formally tested. The imaging, the electroencephalogram, and the cognitive screen were all worth doing and are all normal, but a stack of normal results is not the diagnosis; it satisfies only the criterion that nothing else explains her better. A preceding trauma, adverse life event, or stressor is often present, as here, and the criteria carry specifiers for its presence or absence — the diagnosis holds either way. Two things matter most at the end of this consultation. Her symptoms are not feigned and not intentionally produced: deliberate deception is factitious disorder, feigning for gain is malingering, and neither is what is happening here. And, having already been told once that nothing was wrong, she is owed the explanation the evidence actually supports — the symptoms are real, and they are potentially reversible, because the system is not working properly but there is no underlying structural damage. Prognosis overall is generally poor and depends on multiple factors, yet sudden onset, early diagnosis, short symptom duration, and an identifiable stressor are all favourable, and she has every one of them.
Educational reference
The explanation and decisive case findings were checked against the source below.
Open the clinical referenceFor education and entertainment only. This fictional case is not medical advice and does not replace supervised clinical training, diagnosis, or treatment.
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