PSYCHOGENIC MOTOR WEAKNESS

PSYCHOGENIC MOTOR WEAKNESS

Motor weakness is a common symptom presenting in neurology out-patient department or in an emergency room. It is important to determine whether it is of psychogenic or neurological origin. A few clinical signs can help in this matter.

 1. Hoover's sign- Place the palm of your hand under the heel of foot on the side with "normal" power and ask the patient to lift the "affected" side. In a person with neurologic (genuine) weakness, you would feel the heel (of the normal foot) pressing against your palm. The affected leg would be weaker. On the other hand, in a person with psychogenic weakness, no pressure would be felt on the palm.

 2. Raise the affected arm and let it drop. In a person with neurologic weakness, it falls on the body part if allowed to drop there. On the other hand, in a person with psychogenic weakness, the falling hand avoids any body part in order to avoid getting hurt. Please ensure that while testing, the hand is not allowed to fall over the face to avoid any inadvertent eye injury.

 3. Ask the patient to stand or walk, if he is presented with leg weakness. In a person with psychogenic weakness, they tend to fall over the chair, table or bed, so as to avoid getting injured. On the other hand, a person with neurologic weakness can fall on the ground where he is made to stand (please stand close to avoid any injury to the patient). 

 4. Patient may not be able to raise leg against gravity, while asked to do so while lying on the examination couch. The same person, when made to stand with support, may start walking, when asked to do so. This would be more in favour of a psychogenic weakness. 

 5. Patient may be left in a closed room with a view from one direction. The patient can not see outside, however, the examiner can watch from outside. In a case of psychogenic weakness, the symptoms persist in front of others and disappear when left alone.

 6. Patient may be observed while asleep. A neurologic weakness would not improve during sleep and no limb movements would occur. Whereas, a person with psychogenic weakness may move the limbs during sleep.

 There is no investigation to "confirm" a diagnosis of psychogenic weakness. Therefore, the above mentioned clinical examination steps would be valuable in the diagnosis. It is important to make a definite diagnosis of psychogenic motor weakness at the earliest so that correct treatment can be started under the guidance of a psychiatrist; and unnecessary medicines/investigations can be avoided. 

 Dr Sudhir Kumar MD DM
Consultant Neurologist
Apollo Hospitals, Hyderabad
04023607777/60601066
drsudhirkumar@yahoo.com
https://www.facebook.com/bestneurologist

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