abnormal motor neuorns

Hi, I am a 53yr. old male. I had an emg done for numbness that started in my feet, and now is up to my tighs. the emg rervealed "abnormal motor neuron wave lenght", I am having another test called a single fiber emg done at Un. of Penn. I have weakness in my legs, my tighs are always tight.I also am unstable when walking. do I have MS, ALS ??

[Neuro Forum]

Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.

Without the ability to examine you and obtain a history, I can not tell you what the exact cause of your symptoms is. However I will try to provide you with some useful information.

It is difficult to interpret this statement in your EMG "Abnormal motor neuron wave length", as wave lengths are not typically included in the description of nerve conductions or motor potentials to my knowledge. In ALS, abnormalities on EMG typically include evidence of denervation, and motor unit potentials may be increased, and there may be fasiculation potentials. Single fiber EMG may be used to confirm denervation (denervation means a loss of innervation, a loss of nerve supply). Based on the information you have provided, I can not say for sure whether or not you have ALS. However, I will say that if you have sensory symptoms, which it sounds like you do, numbness in your feet and up to the thighs, this makes ALS unlikely since ALS is predominantly a motor problem.

One possible cause of weakness and numbness with instability in walking is a neuropathy, a problem with the peripheral nerves, and specifically a large fiber neuropathy (a problem with the large nerves in the legs as opposed to the very small nerves that supply the skin, sweat glands, etc). There are several categories of neuropathy, and there are many many causes. Sensory and motor neuropathies can involve just one nerve or several nerves in the body. Some types of sensory neuropathies occur and progress very slowly, others sort of wax and wane (with flare-ups) and some are progressive. One of the most common causes of neuropathy is diabetes, and sometimes only glucose intolerances, or abnormal rises in blood sugar after a glucose load can be the only indication (this is called a oral glucose tolerance test. Other causes include but are not limited to hereditary/genetic causes (such as in a disease called Charcot-Marie-Tooth, in which there is a family history of sensory neuropathy usually from an early age associated with other clinical features such as high-arched feet), autoimmune problems (such as lupus (SLE), Sjogren's, Churg-Strauss (in which asthma also occurs), polyarteritis nodosa, which affects blood vessels), and demyelinating diseases (such as CIDP). Vitamin B12 and B6 deficiency, as well as excess vitamin B6, can also cause neuropathy. Some toxins, such as lead, arsenic, and thalium can cause large fiber sensory neuropathy.Other causes include abnormalities of protein metabolism, as in a type called amyloidosis or monoclonal proteinemia. Infections such as HIV and syphilis can also cause neuropathy or other sensory abnormalities.

If you experience tightness or increased tone in the legs, this may be a sign of spasticity. When a person has spasticity combined with instability in walking, if this is "ataxia", or gait instability due to a problem in part of the brain called the cerebellum, a genetic disorder such as spinocerebellar ataxia is one possibility. Multiple sclerosis is another disorder that causes sensory symptoms and gait instability.

It sounds like you are going to be evaluated soon at a reputable university hospital, I strongly recommend you keep this appointment and I recommend continued follow-up with your physicians.

Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.