Temporary Left Side Numbness & Pain

[bexdesigns]

I have been experiencing numbness and pain in my left leg and arm for almost a year.
It comes on suddenly and lasts  6hrs-48hrs. I usually experience it 2-3times per week.
The numbness makes it very difficult for me to pick up objects or use my hand normally and walking about is risky as the muscles feel weak and unreliable.
When the numbness goes away the left side is gone there seems to be no symptoms at all.
I was diagnosed with hypothyroid earlier this year and am taking levothyroxine.
My GP assumed the numbness is unrelated to the thyroid problems. He believed it could be related to my cervical spine and I had an MRI. It showed abnormal disc wear for my age (27), but no trapped nerves.
One of the specialists who saw me, reviewed the MRI and did a neuro exam asked briefly if my B12 levels had been tested, I didn't know and we didn't discuss it further.
Not knowing what else to do they sent me for physio, which so far has given no improvement.

It led me to read more about hypothyroid, B12 deficiency, etc...
So my question is, what is the cause of the temporary numbness, could it be related to the hypothyroid, could it be B12 deficiency?

Thanks
Bex

[Christopher R Newey, DO]

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 a doctor.

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

Numbness may be a form of sensory neuropathy that is related to a large fiber. These types of sensory neuropathies may progress very slowly, others sort of wax and wane (with flare-ups), and some are progressive. One of the most common causes of this 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. In many neuropathies, both the sensory and motor nerves (the nerves that supply the muscles) are involved, leading to sensory symptoms as well as weakness. The diagnosis of large fiber neuropathy is made by findings on a test called EMG/NCS which assess how well the nerves conduct electricity and how well muscles respond. Rarely, in some cases a lumbar puncture provides useful in formation, and very rarely a nerve biopsy is required.

Without additional neurological findings, it would be difficult to say that the B12 is the cause of the numbness in an otherwise healthy 27 year old. If you do have a B12 level checked, it would be helpful to have an MMA checked. This will increase the sensitivity of the testing.

Lastly, numbness in the leg may be related to the lumbar spine region. If a nerve is compressed as it exits through the bones of the lumbar spine, particularly in an area called the nerve root, a radiculopathy results. The compression could be due to arthritis of the spine or due to a herniated disc or other lesions. The symptoms include pain at the level of the problem (i.e. neck or back etc) and pain that may radiate down the arm or leg (depending on where the problem is). In more advanced cases, muscle weakness or sensory symptoms such as tingling or numbness may occur. A radiculopathy is often diagnosed based on history, physical examination, and MRI of the spine.

I suggest that you follow up with a neurologist to discuss your numbness. More information is needed including the location of the numbness and other associated features. You may benefit from imaging of your lumbar spine.

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

[bexdesigns]

Thank you Christopher for the additional info. I understand no diagnosis can be given, but am keen to try to understand the possible causes further as diagnosis and treatment seems to be very slow here.

I had a nerve conductivity study for both my left arm and left leg, which showed normal conductivity.
I hope that the previous blood screening would have covered many of the other causes you suggested. Glucose intolerance is a possibility with me being slightly overweight, though I haven't spotted any of the early warning signs.
As far as I am aware there are no genetic abnormalities in my family, except for talipes equinovarus.

My understanding of nerve  structure leaves me (and everyone else it seems) bewildered by the numbness and pain, as it occurs in my left leg and left arm at the same time. The MRI I had looked for a trapped nerve in my cervical spine, they found nothing, though the specialist did say due to the on and off nature of the numbness the result wasn't concrete. But based on my understand a trapped nerve in the cervical spine cannot cause numbness in the left leg?  So because the leg and arm numbness occur together it is unlikely to be a trapped nerve?

I am currently being seen by the Rheumatologist who has now taken the wait and see approach, but I'm not sure what we are waiting for other than a miracle!  (My GP sent me to see the Rheumatologist as he had seen me previously for pain and thought he would be the best person to see even though it seems to be neurological.)

I will push for B12 + MMA testing and ask for the Neurology referral, as the wait and see approach isn't helpful when there is no reason for change.

Thank you
Bex