Q. How can I rule out ALS?

Answered by
Dr. J. Mariano Anto Bruno Mascarenhas
and medically reviewed by iCliniq medical review team.
This is a premium question & answer published on Jun 25, 2016 and last reviewed on: Oct 09, 2018

Hi doctor,

About five weeks ago, I started feeling some weakness in my left leg. I have consulted my family doctor and a neurologist. All physical tests showed no actual weakness. There were no other clinical signs and the reflexes were also normal. There is no activity or movement that I cannot do. When I run, I feel normal. The sensation has persisted and is difficult to describe. Sometimes it feels like weakness, but sometimes like an ache down my leg, particularly when I sit down for a longer period of time and then I feel sore on my lower left back, just above by buttocks. Overall, if I had to describe the sensation in my left leg, I will describe it as a sense of weakness. Apart from the persisting feeling of weakness, I have also noticed muscle twitches all over my body, including my left foot and primarily in both my legs. I know I have been aware of these for years, but I have been more aware of them lately. Every morning for the past three to four weeks, my left foot feels tight, a slight pain when I am walking. But, it does not persist all day and if I do not think about it, then it feels normal. If I do think about it, then it feels as if I am going to have foot drop, although it does not actually happen. On top of this, I frequently feel a sense of vibration at the bottom of my left foot particularly when lying or sitting down. It is hard to tell whether this is a spasm or numbness or tingling. In the past two weeks, I have had two periods of probably two to three days where I have felt cramped and tightness in my left leg particularly at the top of my left calf.

I have had a brain MRI, which came back as normal. I have had a left knee ultrasound performed which shows a varicose small saphenous vein and my family doctor does not believe this explains my symptoms. Furthermore, I have had a lumbar CT which returned the following results. At L5-S1 moderate broad left paracentral disc protrusion mildly distorting the anterior aspect of the thecal sac and abutting without displacing the traversing nerve roots. Minor disc extension into the foramen at this level without exiting L5 nerve root impingement. Minor changes in the other levels also as described. However, again, my family doctor does not believe this is the cause of my symptoms. He maintains it is most likely from anxiety. I am a 21 year old medical student and to be completely honest, I made the mistake of initially looking up my symptoms online. I have been very anxious since I started experiencing the sense of weakness, as I am worried about the possibility of having ALS. I have constantly been stretching my legs and trying to test my left leg as a result. What is your recommendation? Also, could you please include what you think of the possibility of ALS, as this is my biggest concern at the moment. Thank you so much for your time.



Welcome to

The various symptoms you have described are due to L5-S1 moderate broad left paracentral disc protrusion mildly distorted the anterior aspect of the thecal sac and abutting without displacing the traversing nerve roots.

When a disc prolapses and compresses the spinal cord in cervical and thoracic levels, we get myelopathy. When it compresses the root, we get radiculopathy.

But, please note that even when a prolapsed disc does not directly compress the spinal cord or nerve root, it can still produce symptoms if it compresses the blood vessels and interferes with blood flow.

As a rule, veins are more easily compressed than arteries and the epidural plexus of veins are compressed by the prolapsed disc.

This leads to venous stasis and the metabolites are not washed away from the nerve roots. However, this compression is dependant on the posture.

When you move a bit, the pressure gets released and the blood flow resumes and the metabolites are washed and the nerve becomes functionally normal.

So, even though you may be having symptoms at one time or another, the moment you walk to your doctor's room and climb the examination couch, all metabolites are washed away and your examination does not find any abnormality.

However, the good news is that this condition can be treated by very simple postural adjustments as follows.

  1. Maximize your lumbar extension as much as possible. Be in lordotic position.
  2. Minimum lumbar flexion as much as possible. Do not bend down.
  3. Avoid riding two wheelers for at least six months.

For further information consult a neurologist online -->

Thank you doctor,

My family doctor did not believe that the CT scan results would show any symptoms. Just wanted to clarify, are you saying that they could definitely cause these symptoms? Would the bulge need to be more severe or is what was in the results a sufficient explanation? As I mentioned in my first question, I am personally very worried and stressed about the possibility of ALS. Can you please explain to me in detail how I can rule it out? I am concerned with the spasms that I am having in my left foot. Specifically, they involved my second and third toe and happen continuously when at rest. Sometimes my whole foot jolts, but mostly the toes. Could this be explained by the CT scan results? I do not have severe pain unless I sit for a long time and then I might get an ache in my bottom left back Could this still be a nerve impingement?



Welcome back to

It is must to consult a neuro surgeon for detailed physical evaluation in case of myelopathy and radiculopathy due to vascular problems.

ALS - amyotrophic lateral sclerosis is a motor neuron disease. Your symptoms are sensation, foot feels tight, a slight pain when walking and a frequent feel vibration. These are all sensory symptoms. Sensory symptoms never occur in a motor neuron disease.

So, you can rule out not only just ALS, but other MNDs as well.

Yes, due to venous stasis which is shown on CT you can have spasms.

This is not nerve impingement. Nerve Impingement means the disc is pressing on the nerve. In your case, the disc is just pressing on the nearby veins and arteries and not directly on the nerve.

For further information consult a neurologist online -->

Thank you doctor,

I just completed an EMG and nerve conduction test and I have attached the results. At the end the report, the right upper and lower limb NCS were normal. EMG of left and right lower limb muscles showed occasional fasciculations, but no evidence of fibrillation potentials or sharp waves and normal recruitment. The occurrence of left calf fasciculations does not correlate with a sensation of toe twitching. What do you think of these findings? Can I conclusively rule out ALS with these findings?



Welcome back to

  • I have gone through the EMG report (attachment removed to protect patient identity).
  • This is not suggestive of ALS. Please be happy and cheerful.

For further doubts consult a neurologist online -->

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