Stroke And Tinnitus: Is There A Link?

Tinnitus, or the perception of sound without an external source, is a symptom that may precede a stroke. A 2017 study published in the journal PLOS One found that tinnitus could be a novel risk factor or clinical indicator for ischemic stroke. While further research is needed, the study's scientists hypothesised that stroke and tinnitus share several pathophysiological mechanisms, such as arterial stiffening, hypoxia, and increased sympathetic activity. Tinnitus may also be caused by interrupted or restricted blood flow to a patient's ear.

Tinnitus may be a novel risk factor for ischemic stroke

Tinnitus is defined as the conscious perception of an auditory non-speech sensation, such as hissing, sizzling, and ringing, in the absence of a corresponding external sound. Epidemiological studies have found the prevalence of tinnitus to be approximately 10% of the adult population, regardless of sex. However, a recent cross-sectional survey in South Korea showed that the prevalence of tinnitus was 20.7%.

Tinnitus can occur in association with a number of otological diseases, including otosclerosis, Ménière’s disease, and vestibular schwannoma, as well as other metabolic abnormalities and psychiatric disturbances. Specifically, sensorineural hearing loss, obesity, smoking, alcohol consumption, previous head injuries, hypertension, sleep disturbances, and certain medications are a few of the possible risk factors for the sensorineural type of tinnitus.

A 2017 study published in the journal PLOS One found a significant association between tinnitus and a higher risk of incident ischemic cerebrovascular disease (ICVD) among young and middle-aged patients. The study used Taiwan's National Health Insurance Research Database to identify 3,474 patients aged 20–45 years with incident ICVD diagnosed between 2000 and 2010 and 17,370 controls. The risk of ICVD associated with tinnitus was assessed using multiple logistic regression analyses, which showed that tinnitus was significantly associated with a higher risk of ICVD, particularly in those under 40 years of age.

The study concluded that tinnitus could be a novel risk factor or clinical indicator for young ischemic stroke and recommended further investigations to elucidate the underlying mechanisms. The association between tinnitus and stroke could be explained by several shared pathophysiological mechanisms, such as arterial stiffening, hypoxia, oxidative stress, neural inflammation, poor sleep, and increased sympathetic activity.

Tinnitus and stroke share several pathophysiological mechanisms

• Arterial stiffening: Arterial stiffness can lead to impaired cochlear microcirculation. A higher common carotid artery stiffness index was found to be significantly associated with the formation and severity of tinnitus. Arterial stiffness is also associated with a higher incidence of stroke.
• Hypoxia: This is the condition in which the body or a region of the body is deprived of adequate oxygen supply.
• Oxidative stress: This is an imbalance between free radicals and antioxidants in the body, which can lead to nerve cell damage.
• Neural inflammation: This is inflammation of the nervous tissue, which can be caused by various factors such as infection, autoimmune disorders, or physical injury.
• Poor sleep: Sleep disturbances are associated with both tinnitus and stroke.
• Increased sympathetic activity: The sympathetic nervous system is responsible for the body's fight-or-flight response, and increased activity can lead to physiological changes such as increased heart rate and blood pressure.

Tinnitus may be a result of interrupted or restricted blood flow to the ear

Tinnitus is the perception of sound that does not have an external source, so people other than the affected individual cannot hear it. It is commonly described as a ringing sound, but some people hear other types of sounds, such as roaring, buzzing, or whooshing. Tinnitus is usually not a sign of anything serious, but it can be linked to a stroke.

A 2017 study published in the journal PLOS One found that "tinnitus could be a novel risk factor or clinical indicator" for ischemic stroke. The study also reported a "strong association between tinnitus and young stroke", suggesting that tinnitus could precede a stroke as an independent risk factor or as an intermediate role in the association between vascular disease and stroke.

One of the mechanisms underpinning this potential association is increased sympathetic activity. Another hypothesis is that tinnitus may occur as a result of interrupted or restricted blood flow to a patient's ear. This is supported by the fact that tinnitus is often associated with arterial hypertension and sensorineural hearing impairment.

Tinnitus is also linked to several conditions that can cause interrupted or restricted blood flow to the ear, including:

• Atherosclerosis: a hardening of the arteries that can make blood flow uneven and noisier.
• High blood pressure (hypertension): which can lead to a change in blood flow, and things like stress, alcohol, and caffeine can make the noise more noticeable.
• Head and neck tumours: which can press on blood vessels and cause noise.
• Arteriovenous malformations: tangles of blood vessels affecting the connections between veins and arteries.
• Middle ear tumours: small tumours in the middle ear with many blood vessels that can cause tinnitus when blood flows through them.

Tinnitus is associated with a higher risk of intracerebral vascular disease

Tinnitus and ICVD may share common pathophysiologic mechanisms such as arterial stiffening, which can lead to impaired cochlear microcirculation and a higher incidence of stroke. Other potential mechanisms underpinning the association between tinnitus and stroke include hypoxia, oxidative stress, neural inflammation, poor sleep, and increased sympathetic activity.

While the 2017 study was one of the few to make a connection between tinnitus and intracerebral vascular disease, the scientists involved emphasised that further research was warranted.

Tinnitus is a common symptom of other conditions, including hypertension and sleep disturbances

Tinnitus is a symptom that can precede a stroke, and it is associated with a number of other conditions, including hypertension and sleep disturbances.

Hypertension, or high blood pressure, is a common condition that affects a large proportion of the global population. It is characterised by raised and sustained arterial pressure levels and is a significant risk factor for the development of both ischemic and hemorrhagic strokes. Several studies have found a positive association between hypertension and tinnitus, with hypertension treatment, such as diuretics and angiotensin-converting enzyme (ACE) inhibitors, potentially contributing to tinnitus pathophysiology. However, the relationship between hypertension and tinnitus is complex and may be influenced by other factors such as age, hearing loss, and comorbidities like diabetes and dyslipidemia.

Sleep disturbances, including sleep apnea, have also been linked to tinnitus in several studies. Sleep problems can be both a cause and an effect of tinnitus, creating a cycle that can be challenging to break. Poor sleep can exacerbate tinnitus symptoms, and the presence of tinnitus can disrupt sleep quality, leading to a bidirectional relationship that can negatively impact overall health and well-being.

While the exact mechanisms underlying the association between tinnitus and conditions like hypertension and sleep disturbances are not fully understood, it is clear that tinnitus is a multifaceted symptom that can be influenced by a range of physiological and environmental factors. Further research is needed to fully elucidate the complex relationships between tinnitus and other health conditions, which could inform the development of more effective prevention and treatment strategies.

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