Foot Drop

[sarahkelly]

Hi there
I'm currently a student so forgive if my questions is a bit silly but is foot drop something commonly seen in an outpatients setting? If so how do you determine what is causing it? And how is foot drop treated? and my most important question, how does treatment differ depending on the cause?(as in when is E-stim used and not used...)
I can only guess if there's already strenght there its with a theraband, but I saw a patient on a recent placement and there was literally nothing. I'm presuming the afo you mentioned is to prevent tighting of the gastroc's is this its only function?

[gcoe]

Hi Sarah

No foot drop is not that common a syndrome to see in musculoskeletal outpatients as neurological disease is the most common underlying conditions that give rise to foot drop. The term is rather colloquial and uninformative and really anything that gives rise to the weakness or paralysis of the dorsiflexors of the foot can give rise to foot drop. So that means anything in the motor system. You can classify this into: UMN syndromes, LMN diseases and injuries and disorders of the muscle. Because of the serious nature of most of these diseases you should always refer back to get a diagnosis underway if a patient fronts up to outpatients without a known reason.

1. UMN. Stroke is the most common cause but CNS tumors MS, TBI, spinal cord disease (eg transverse myelitis) or injury can all give rise to foot drop. There are three impairments that interact and can contribute to foot drop:
a) Weakness/paralysis. Measurement is by MMT or Hand held dynamometry. Usually when treating this your suggestion of NMES/FES is often a great idea and even when there is complete paralysis you can get a contraction - think about it - the lower motor neurone/muscle circuit is all completely intact - so good involuntary contractions can be ached with FES. In the chronic UMN situation the LMN and muscles will atrophy but this process is often surprisingly slow. The challenge with FES is trying to get a pairing up of the involuntary contraction with volition so timing your instructions so the patient thinks hard about contracting the muscle while the machine is stimulating the muscle is the key. TAsk oriented training is another approach so practicing contracting the muscle in relation to walking practice is key. You can combine the FES with gait practice. when you get to grades 2+ and above progressive resistance training is good and yes theraband is a good place to start. Your patient was way too weak for this. To compensate for the deficit ankle-foot orothses are commonly used. and these can also take a role in preventing contracture of the plantar flexors. One newer innovation is an electrical AFO - has a stimulator of the dorsiflexors that is operated either by pressure off a heal switch or an electrogoniometer. Many patients find these very helpful but they cost a lot.
b)spasticity of the plantar flexors. Measurement is by Tardieu scale or modified Ashworth (tardieu is better). Spasticity can interfere with achieving heel strike. The management is controversial and many physios make all sorts of false claims about being able to control spasticity through handling techniques. If the "catch" happens early in the movement and if the spasticity is very marked and there is weakness of the dorsiflexors then botox injections combined with active strengthening and gait reed can be effective.
c)contracture of the plantar flexors/ankle joint. Assess three things: decreased end range of movement, increased resistance (not velocity dependent) through range and presence of deformity at rest. Measurement is by goniometry and the Lidcombe goniometer is one of the best clinical tools for measuring plantar flexions contracture. Contracture is usually bad news once established. contracture is very difficult to reverse by even quite vigorous and sustained stretching procedures. serial casting can work well with contracture and spasticity combinations but this usually way beyond the outpatient setting - it requires a highly skilled neurophysio to safely do this - risk of pressure areas and break down is high.
d)combinations of weakness of the three above impairments. This is common in the UMN syndrome particularly in the more chronic situation. Preventing further contracture is key and aggressive attempts to improve the strength of the dorsiflexors is best

2. Lower Motor Neuron Disease/injury could involve: the peroneal nerve, sciatica (severe), lumbosacral plexus, L5 Nerve root - so anywhere along the course of the nerve. Diseases could be diabetic neuropathy or other neuropathy. Sudden onset of bilateral foot drop can indicate the onset of Guillain Barre Syndrome - always a reason for referring on. You won't see marked foot drop in your everyday nerve root lesion from a disc trespass so when you see it again - alerts you to cause for concern. Measurement is by MMT or Hand held Dynamometry. Testing for reflexes can help clinically to differentiate between UMN and LMN disease - LMN reflexes will always be reduced or absent. UMN will often be brisk although also can be diminished or absent. Management is strength training but this has less options open to you. FES is usually fairly useless - in this case the command control system is all intact and and is connected to the alpha motor neuron and gamma motor neuron. The problem is the output. So you won't usually get much happening with LMN disease. However...occasionally you can get something - presumably more like a memory jog to the nervous system "this is how you lift your foot". If there is marked sensory loss FES may be contraindicated. One technique you could try is mental practice - it is worth reading up about mental practice for UMN and LMN diease. Again if you have a grade 2+ or above then PRT is good. Direct stimulation of the muscle in the case of paralysis is an old treatment but you need a specialized stimulator and I don't think the evidence is great for that - I would have to look that up

3) Myopathy, diseases of the Neuromuscular junction can all cause foot drop. Treatment is as for LMN disease

one condition that covers the whole motor system is Motor Neurone Disease or (ALS in the USA) Generally this is a very serious disease and foot drop can be the first sign.

Hope this helps. I would be interested to know on reflection what you think you would do to manage your patient?