Today I would like to advise on what I consider to be the correct use of a Tendon Hammer to perform the Babinski sign for determining upper motor neurone lesions.
Essentially, the end tips of most of the modern hammers are far too sharp and can be very uncomfortable to use on a patient's foot especially when there are a team of doctors and students all having a try to practise their skills to elicit the sign.
Unless the end of the tendon hammer is blunted it is therefore not appropriate to use the sharp tip for eliciting the Babinski sign. Please try and use another type of blunted instrument.
In order to understand just how uncomfortable it is to perform Babinski sign on a patient with a sharp tipped tendon hammer I suggest you take off your own shoes and socks and get a colleague to perform it on you. It is not a pleasant experience. Never do to a patient what you would not have done to yourself!
Use of the tip of the tendon hammer by doctors in the UK MRCP examinations can lead to failing that section of the examination. Never put your patient through unnecessary discomfort. Things that can be used are 'orange' sticks, your thumb (although not in an formal examination!), a blunt tipped tongue depressor. The former and latter can be disposed of although I would recommend washing your thumb rather than trying to dispose of it :-p
Just to remind you of the correct technique, ensure that the toes are neutrally positioned e.g. not pointing up or down. Use the blunt instrument to excite the lateral border of the foot starting at the heal and running caudally towards the fifth metatarsal head followed by a medial turn across the foot towards the remaining metatarsal heads in the direction of the great toe.
A negative sign is visualised by the toes plantar flexing [true flexion]. A positive sign is visualised by the toes moving into dorsiflexion [plantar extension]. The most sensitive aspect is visualising the movement of the Great Toe because it may be the only toe that moves.
Sometimes the excitation of the plantar elicits no response at all and it can be due to peripheral neuropathy or myopathy although it may also be seen in early stroke or spinal cord injuries. Drugs also temporarily influence the Babinski response and include sedative drugs such as propofol, general anaesthetics etc.