Can hypothyroidism cause a mini stroke?

Acute ischemic stroke and hypothyroidism

Background: In Kentucky, the incidence and mortality associated with stroke are among the highest in the United States. Treatment of modifiable risk factors can significantly prevent stroke. Identification of additional risk factors may further reduce stroke risk. Hypothyroidism is linked to altered lipid metabolism and is associated with hyperhomocysteinemia. In this study, we examined a possible association between acute ischemic stroke (AIS) and hypothyroidism.

Methods: Records were reviewed on all consecutive patients admitted to the University of Louisville Stroke Center with a diagnosis of AIS or transient ischemic attack (TIA).

Result: Our data revealed that 12% of patients with AIS or TIA had hypothyroidism. A significant difference was found between the prevalence of hyperhomocysteinemia in patients with hypothyroidism (45.4%) compared with the prevalence of hyperhomocysteinemia in euthyroid patients (27.8%).

Conclusion: Hypothyroidism is common in patients with AIS and TIA. Elevated homocysteine levels associated with hypothyroidism suggest that hypothyroidism may represent a modifiable stroke risk factor. Prospective studies are needed to verify this association.

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Stroke in Dogs

Chances are, you know someone who has had a stroke and have seen the life-altering impact it can have. As a pet parent, you might be surprised to learn that dogs can have strokes, too, although much less frequently than people do.

With the increased availability of MRI and CT scans for pets, strokes are being diagnosed more frequently, says Dr. Brett Levitzke, medical director of the Veterinary Emergency and Referral Group in Brooklyn, N.Y. Understanding the causes, symptoms, and treatment of strokes in dogs will help you to be a savvy pet parent.

What Is a Stroke?

Dr. Virginia Sinnott, of the Massachusetts Society for the Prevention of Cruelty to Animals Angell Medical Center, explains that a stroke is caused by a loss of blood flow to parts of the brain that leads to tissue damage and neurologic abnormalities.

There are two mechanisms that cause strokes in dogs:

• An obstruction in blood vessels (ischemic strokes), which often occur due to things like blood clots, tumors, inflammation, and infections
• Bleeds in the brain (hemorrhagic strokes), which result from the rupture of blood vessels or blood clotting disorders.

Ischemic strokes are more common in dogs than hemorrhagic strokes.

Symptoms of a Stroke in Dogs

Signs of strokes in animals can be similar to those in people, though animals do not obviously suffer from slurred speech or loss of memory. Symptoms vary depending on the location in the brain where the stroke occurred, Dr. Levitzke says.

“Even in people, these signs can be subtle, and since animals can’t speak and tell us they ‘feel dizzy’ or ‘I can no longer see out of my left eye,’ subtle true strokes can go unnoticed in animals,” Dr. Sinnott adds.

However, it is more common to see massive strokes in dogs, Sinnott says, but pet parents sometimes mistake fainting spells (syncope) for strokes. “Both are very serious and require immediate attention by a veterinarian,” Dr. Sinnott says.

Symptoms of strokes in dogs can include:

• Inability to walk or walking with an uncoordinated gait
• Head tilt
• Abnormal eye movements, side to side or rotary (nystagmus)
• Abnormal eye positioning (strabismus)
• Loss of consciousness
• Abnormal behavior
• Falling to one side
• Blindness
• Abnormal behavior
• Rapid onset of symptoms

“Generally, one minute owners report the pet is fine, and the next [the pet] cannot get up. These signs may last for a few minutes or much longer (hours to days),” Dr. Sinnott says.

It’s important to note, however, that many of these symptoms are seen with other more common conditions in dogs including idiopathic vestibular disease, which frequently affects older dogs, and even severe ear infections.

Causes of Strokes in Dogs

Dr. Sinnott says vets typically see only a couple of cases of strokes in dogs every year, and when they do occur, it is usually in a very old dog who has diseases that can increase the risk of clots or bleeding.

“The signs can be frightening and may be associated with discomfort for the dog, and some owners elect to euthanize their pets,” Dr. Sinnott says in the cases of severe strokes in very old dogs.

The underlying diseases that can cause strokes in dogs include:

• Kidney disease
• Cushing’s disease (hyperadrenocorticism)
• Hypertension
• Diabetes
• Heart disease
• Bleeding disorders
• Hypothyroidism
• Cancer

In some cases, high doses of steroids, such as prednisone, can lead to stroke.

While no one breed is more likely to suffer a stroke than another, Dr. Levitzke says some breeds are prone to some of the underlying diseases that cause strokes, such as Cavalier King Charles Spaniels, which have a high rate of heart disease.

How Vets Diagnose Strokes in Dogs

Proper diagnosis is the most important part of treating strokes in dogs. A fainting spell that might look like a stroke can be caused by an abnormal heart rhythm, which can be life-threatening. Your vet can distinguish a stroke from other diseases that cause similar symptoms with a physical examination, including examining your dog’s heart functions to rule out a cardiac problem that can cause fainting. Tests may include an electrocardiogram (ECG), chest X-rays, and possibly a cardiac ultrasound, Dr. Sinnott says.

If the heart is normal, the brain can be examined using an MRI or CAT scan. Your vet might also do more testing to look for underlying diseases that could cause a blood clot, such as hormone testing, bloodwork, and urinalysis.

Treatment of Strokes in Dogs

Once the cause is determined, treatment will aim to resolve it, Dr. Levitzke says. If a clot caused the stroke, blood thinners might be prescribed. High blood pressure medications can be used for a stroke caused by hypertension.

“The neurologic signs associated with a stroke are allowed to resolve on their own as the patient’s body re-establishes blood flow to the affected area and swelling resolves. Medications such as steroids, mannitol, and hypertonic saline can help resolve swelling in the brain,” Dr. Levitzke says.

Supplemental oxygen is a mainstay of treatment to maximize oxygen delivery to damaged tissues and promote healing.

Managing urination and defecation, maintaining good nutrition, and physical therapy (massage, passive range of motion of limbs, if needed, etc.) are also important for healing. “The brain is very adept at recovery, though it can take time,” says Dr. Levitzke.

Preventing Strokes in Dogs

Because strokes in dogs are often associated with underlying disease processes, routine check-ups with a veterinarian and screening blood work can identify potential causes that can be addressed before a stroke happens, says Dr. Levitzke. Staying on top of wellness care as dogs age is essential to their health and happiness.

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