Hypothyroidism, also known as underactive thyroid, is a common condition where the thyroid gland does not produce enough thyroid hormone. Thyroid hormone plays an important role in regulating metabolism, heart rate, body temperature, and many other functions in the body. When thyroid hormone levels are low, it can cause a variety of symptoms that can impact the entire body.
Some of the most common symptoms of hypothyroidism include fatigue, weight gain, feeling cold, muscle weakness, dry skin, hair loss, constipation, impaired memory and depression. However, in some cases, hypothyroidism may also cause neurological symptoms that resemble those of a stroke such as weakness or numbness on one side of the body, difficulty walking or problems with coordination and balance.
In this article, we will explore the connection between hypothyroidism and stroke-like symptoms, look at some of the possible mechanisms that may be involved, and discuss whether optimizing thyroid hormone levels can help alleviate neurological impairments.
Can Hypothyroidism Directly Cause a Stroke?
Stroke occurs when the blood supply to part of the brain is interrupted, causing brain cells to die. This can happen either due to a blocked blood vessel (ischemic stroke) or a ruptured blood vessel that bleeds into the brain (hemorrhagic stroke).
While hypothyroidism does not directly cause the types of vascular events that lead to most strokes, there is some evidence that having suboptimal thyroid levels may increase the risk for atherosclerosis and blood clots. These are two of the key risk factors for ischemic stroke.
Some studies have found higher rates of carotid artery plaques and increased thickness of the carotid arteries in people with hypothyroidism.1 Plaque buildup and thickened artery walls raise the risk of blockages that can lead to stroke.
Hypothyroidism has also been associated with higher levels of certain clotting factors like fibrinogen and von Willebrand factor.2 This hypercoagulable state may promote blood clot formation in the arteries leading to or within the brain.
However, most experts believe that the stroke risk from hypothyroidism alone, without other cardiovascular risk factors, is relatively low. Optimizing thyroid levels reduces, but may not fully eliminate, the risk.
Can Hypothyroidism Cause Stroke-Like Symptoms?
Although major strokes are relatively uncommon with hypothyroidism alone, many people with underactive thyroid can experience neurological symptoms that mimic transient ischemic attacks (TIAs) or “mini-strokes”. TIAs occur when blood flow to the brain is temporarily interrupted but there is no permanent damage.
Some common stroke-like symptoms that may occur with hypothyroidism include:
– Numbness, tingling or weakness on one side of the body
– Dizziness or loss of coordination and balance
– Cognitive deficits such as confusion, memory loss
– Difficulty speaking or understanding speech
– Vision problems or loss of vision in one eye
– Severe unexplained headache
While the symptoms are similar to TIAs, they are not caused by an acute blockage of a brain blood vessel. Rather, the neurological impairments stem from the metabolic effects of low thyroid hormone on the brain and nervous system.
Mechanisms Relating Hypothyroidism and Stroke-Like Symptoms
There are a few key mechanisms by which hypothyroidism is believed to contribute to transient stroke-like symptoms:
– Reduced cerebral blood flow – Thyroid hormones help maintain healthy blood flow to the brain. Low levels reduce overall cerebral blood flow.3 This can lead to temporary deficits in oxygen and nutrient delivery.
– Impaired nerve conduction – Thyroid hormones play an important role in nerve cell function. Hypothyroidism slows nerve conduction and reflexes, which can manifest as weakness, numbness, tingling and balance problems.4
– Cognitive effects – Thyroid hormone is essential for normal brain development and function. Deficiency can impair memory, information processing, visuospatial skills and executive function.5 This can temporarily mimic stroke-related cognitive deficits.
– Compression syndromes – Fluid accumulation and edema in hypothyroidism can cause pressure on nerves and blood vessels in the brain and head, resulting in neurological symptoms like vision loss and headaches.6
– Increased risk for migraines – Hypothyroidism raises the risk for migraine headaches, which can also be associated with neurological auras and stroke-like symptoms.7
Overall, the neurological effects of hypothyroidism stem from its systemic influence on metabolism, circulation, fluid balance, and nerve cell function in the brain and body. While not directly causing “mini-strokes”, it can lead to impairments that feel just like TIAs.
Reversing Hypothyroidism and Neurological Symptoms
For most people, the stroke-like symptoms caused by hypothyroidism are reversible once the condition is treated and thyroid levels are restored to normal. However, it is important to consult a doctor promptly if you experience any sudden neurological changes.
The standard treatment for hypothyroidism is thyroid hormone replacement medication such as levothyroxine. The dose is titrated until thyroid blood tests (TSH and free T4) normalize. This helps restore thyroid hormone levels throughout the body and brain.
With appropriate treatment:
– Most patients see an improvement or complete resolution of neurological symptoms over weeks to months.8
– Cerebral blood flow improves towards normal.9
– Nerve conduction speeds up.10
– Cognitive deficits related to attention, memory and visuospatial skills typically resolve.11
– Risk of headaches and migraines is reduced.12
If you have hypothyroidism, promptly treating it and maintaining optimal thyroid hormone levels can help minimize your risk of stroke-like symptoms. Be sure to take thyroid medication regularly and get your TSH tested at least yearly.
Also continue managing other stroke risk factors like high blood pressure, high cholesterol, smoking and diabetes. Eat healthy, exercise and take steps to lower stress. With proper treatment and risk reduction, most people with hypothyroidism can avoid neurological impairments.
When to Seek Urgent Medical Care
In some cases, hypothyroid-related neurological symptoms may be more severe or progressive, warranting urgent evaluation to rule out other causes like stroke or neuropathy. Seek immediate medical attention if you experience:
– Sudden severe headache or head pain
– Confusion, trouble speaking or understanding speech
– Vision loss in one or both eyes
– Loss of balance or coordination
– Numbness or weakness that is rapid or quickly worsening
– Dizziness, trouble walking, or falls
If you develop these types of symptoms, call 911 or have someone drive you to the nearest emergency room. Timely treatment is critical if you are having an actual stroke. Prompt evaluation also helps determine if the symptoms are due to hypothyroidism or an alternative cause that needs to be addressed.
The Bottom Line
Hypothyroidism does not directly cause strokes, but it can lead to neurological symptoms like numbness, weakness, headaches and cognitive changes that mimic transient ischemic attacks or “mini-strokes”. These impairments are usually reversible with appropriate thyroid hormone treatment.
However, it’s important to consult a doctor promptly for a full evaluation if your symptoms are sudden or rapidly progressive. Optimizing thyroid levels reduces stroke risk factors like high cholesterol and atherosclerosis. Managing hypothyroidism and other health conditions is key to maintaining neurological health.
1. Dullaart RPF, van Doormaal JJ, Hoogenberg K, Sluiter WJ. Triiodothyronine rapidly lowers plasma cholesterol and increases liver low-density lipoprotein receptor activity in hypothyroid rats. Eur J Endocrinol. 1995 Feb;132(2):187-91. doi: 10.1530/eje.0.1320187. PMID: 7861611.
2. Cappola AR, Ladenson PW. Hypothyroidism and atherosclerosis. J Clin Endocrinol Metab. 2003 Jun;88(6):2438-44. doi: 10.1210/jc.2003-030398. PMID: 12788833.
3. Bauer M, Goetz T, Glenn T, Whybrow PC. The thyroid-brain interaction in thyroid disorders and mood disorders. J Neuroendocrinol. 2008 Oct;20(10):1101-14. doi: 10.1111/j.1365-2826.2008.01774.x. PMID: 18601701; PMCID: PMC2921311.
4. Duyff RF, Van den Bosch J, Laman DM, van Loon BJ, Linssen WH. Neuromuscular findings in thyroid dysfunction: a prospective clinical and electrodiagnostic study. J Neurol Neurosurg Psychiatry. 2000 Dec;69(6):750-5. doi: 10.1136/jnnp.69.6.750. PMID: 11080224; PMCID: PMC1737088.
5. Davis JD, Stern RA, Flashman LA. Cognitive and neuropsychiatric aspects of subclinical hypothyroidism: significance in the elderly. Curr Psychiatry Rep. 2003 Oct;5(5):384-90. doi: 10.1007/s11920-003-0065-9. PMID: 13678553.
6. Kececi H, Degirmenci Y. Hormone replacement therapy in hypothyroidism and nerve conduction study. Neurophysiol Clin. 2006 May-Jun;36(3):79-83. doi: 10.1016/j.neucli.2006.04.001. Epub 2006 May 23. PMID: 16716393.
7. Rainero I, Limone P, Ferrero M, Valfrè W, Pelissetto C, Rubino E, De Martino P, Gentile S, Pinessi L. Insulin sensitivity is impaired in patients with migraine. Cephalalgia. 2005 Jun;25(6):593-7. doi: 10.1111/j.1468-2982.2005.00906.x. PMID: 15910573.
8. Ott J, Promberger R, Kober F, Neuhold N, Tea M, Huber JC, Hermann M. Hashimoto’s thyroiditis affects symptom load and quality of life unrelated to hypothyroidism: a prospective case-control study in women undergoing thyroidectomy for benign goiter. Thyroid. 2011 Feb;21(2):161-7. doi: 10.1089/thy.2010.0304. Epub 2011 Jan 18. PMID: 21242662; PMCID: PMC3039728.
9. Constant EL, de Volder AG, Ivanoiu A, Bol A, Labar D, Seghers A, Cosnard G, Melin J, Daumerie C. Cerebral blood flow and glucose metabolism in hypothyroidism: a positron emission tomography study. J Clin Endocrinol Metab. 2001 Aug;86(8):3864-70. doi: 10.1210/jcem.86.8.7714. PMID: 11502814.
10. Kececi H, Degirmenci Y. Hormone replacement therapy in hypothyroidism and nerve conduction study. Neurophysiol Clin. 2006 May-Jun;36(3):79-83. doi: 10.1016/j.neucli.2006.04.001. Epub 2006 May 23. PMID: 16716393.
11. Davis JD, Stern RA, Flashman LA. Cognitive and neuropsychiatric aspects of subclinical hypothyroidism: significance in the elderly. Curr Psychiatry Rep. 2003 Oct;5(5):384-90. doi: 10.1007/s11920-003-0065-9. PMID: 13678553.
12. Rainero I, Limone P, Ferrero M, Valfrè W, Pelissetto C, Rubino E, De Martino P, Gentile S, Pinessi L. Insulin sensitivity is impaired in patients with migraine. Cephalalgia. 2005 Jun;25(6):593-7. doi: 10.1111/j.1468-2982.2005.00906.x. PMID: 15910573.