What does the thyroid gland have to do with carpal tunnel syndrome (CTS)? The short answer is, a lot! But the “how” requires a more detailed explanation…
The carpal tunnel is made up of eight small bones in the wrist that form a tunnel, with the “floor” of the tunnel located on the palm side of the wrist. CTS is caused by the median nerve getting pinched as it travels through the carpal tunnel, which results in numbness and tingling into the middle three fingers (index, third, and fourth) initially, and usually weakness of the grip later.
The thyroid gland is located at the base of the neck just below the “Adam’s Apple” (which is really thyroid cartilage). There are two “lobes” located on either side of the windpipe (trachea), and a small bridge of thyroid tissue crosses over the front connecting the two lobes (called the “isthmus”) in most of us.
The thyroid belongs to the endocrine system, which is controlled by the pituitary or “master” gland that is located inside the head. These glands secrete hormones into the bloodstream that influence the body in a variety of ways. Some of the other “members” of the endocrine system include the adrenals, the parathyroid, the gonads (testicles or ovaries), the insulin producing part of the pancreas, the mammary glands, and more. Think of the endocrine system as a “team” and the pituitary gland as the “coach.”
The thyroid’s role on the endocrine “team” is to release hormones (primarily T3 and T4) that regulate our metabolism/metabolic rate (digestion, heart rate, breathing, body temperature, etc.).
It’s been known for a long time that thyroid disease—particularly low thyroid function—increases one’s risk for developing CTS. One thought is that the type of swelling that occurs with hypothyroid (called “myxedema”) places enough pressure on the median nerve to pinch it, resulting in the classic signs and symptoms of CTS.
More recently, researchers used ultrasound to measure the size of the median nerve (called the cross-sectional area or CSA) in 30 patients with newly diagnosed primary hypothyroidism and comparable “normal” controls (similar size/BMI, similar gender, and age). In those with hypothyroidism, the cross sectional size of the median nerve was larger than those measured in the normal group, and four of the hypothyroid patients already began experiencing CTS signs and symptoms. After receiving treatment to restore their thyroid levels, both the size of the median nerve was reduced and the symptoms that were present resolved within three months.
This study points out the significant relationship between the thyroid and its effect on CTS. Doctors of chiropractic treat the mechanical causes of CTS very successfully, but they may rely on the expertise of a “team” of healthcare providers to treat the patient when necessary.