The Neuropsychiatry of Tinnitus: Causes and Treatments
Tinnitus is associated with psychiatric disorders. Marciano et al found that 77% of tinnitus patients met criteria for a psychiatric disorder. They most frequently had affective, anxiety and somatoform disorders (DSMIV-Axis I), but often also had personality disorders (DSM-IV Axis II). This was also seen by Zoger et al, who found that the lifetime prevalence of depressive and anxiety disorders in tinnitus patients was 62% and 45%, respectively. Many studies have shown that Beck Anxiety Inventory Scores and Beck Depression Inventory Scores were significantly higher in tinnitus patients than in normal control subjects. A population study found that emotional exhaustion was a strong predictor of the severity of tinnitus. Also, a decrease in depression was associated with a decrease in tinnitus prevalence. Finally, a few studies looked at a possible association between tinnitus and suicide though this association was confounded by comorbid psychiatric conditions, particularly depression. However, one study found that frequent tinnitus was associated with generalised anxiety disorder but not major depressive disorder.
Patients with tinnitus have higher scores on paranoid ideation, psychotism and hostility. Sometimes, it can be difficult to distinguish between tinnitus and psychotic symptoms, especially in patients with schizophrenia.
Tinnitus has also been described as a somatoform disorder. The WHO found that 42% of the patients with somatisation disorder had tinnitus with autonomic arousal as a common link.
Studies are also being carried out looking at the effects of stress on tinnitus, as well as tinnitus on stress levels. People who are highly stressed are about as likely to develop tinnitus as people exposed to occupational noise. Exposure to both high stress and occupational noise doubles the chance of developing tinnitus. Another study found a linear association between stress (health-related and/or work-related stress) and the magnitude and duration of tinnitus. Tinnitus sufferers may associate their first awareness of tinnitus to changes in their life, such as divorce, being laid off, sickness in family members, accidents, surgery or having their ears syringed. These events can heighten the brain's arousal, and the tinnitus may be noted cortically. This interaction between reduced auditory sensation and brain compensation might explain why some people are very bothered by their tinnitus and others just adjust to it.
Moreover, allostasis, or the body's ability to adapt to stress, might also be linked to tinnitus. Allostatic load has been shown to affect tissues and organs by causing neuronal atrophy, atherosclerosis, obesity, bone demineralisation and mood disorders, and by decreasing the functioning of the immune system.
Difficulty falling asleep is often one of the most common complaints of tinnitus patients. Sleep complaints include delayed sleep, morning awakenings, mid sleep awakenings, morning fatigue and chronic fatigue. To date, three studies have been carried out with polysomnography to evaluate these sleep complaints. Cronlein et al found longer sleep latency in patients with tinnitus compared with patients without tinnitus referred to a sleep centre. However, there were no other differences in objective or subjective complaints of these patients. Burgos et al found that compared with healthy controls, tinnitus patients had worse sleep on subjective and objective complaints (sleep efficiency, total sleep time and number of periods of awakening). Hebert et al found that compared with healthy controls, tinnitus patients had lower subjective sleep quality but had the same objective sleep quality.
Traumatic brain injury (TBI) is a significant cause of tinnitus. In military personnel with TBI, 38% complained of tinnitus. Various types of trauma can precede the onset of tinnitus. These traumas can include noise, brain injuries that injure the auditory pathways, neck injuries and emotional trauma. Interestingly, patients who had trauma-associated tinnitus reported pain symptoms more than non-trauma-related tinnitus patients. They also had higher rates of vertigo and dizziness.
In a study examining the impact of trauma on tinnitus, post-traumatic tinnitus was associated with higher distress levels. Patients with post-traumatic tinnitus may require specialised treatment from those of non-trauma-associated tinnitus patients.
Tinnitus can also be associated with certain pain disorders, such as headache. In one case series, 71 out of 112 patients with a primary headache disorder had tinnitus. Up to 26% of basilar migraine patients also have tinnitus. A few patients have been reported to have tinnitus whereby the tinnitus intensity increased only and consistently during headache exacerbations. In these patients, the cutaneous allodynia they reported occurred in parallel with the development of the tinnitus. Volcy et al hypothesised that in patients with headache, the tinnitus may be from spontaneous and aberrant neural activity, may be an allodynic symptom triggered by the trigemino-cervical complex centralisation and/or from cerebral hyperexcitability. Tinnitus may also rarely be seen in migrainous infarction. In idiopathic intracranial hypertension (IIH), 87% of patients described tinnitus. The tinnitus may be caused by compression of the transverse and sigmoid sinuses as well as compression of the eighth cranial nerve. It has been suggested that although the symptoms of idiopathic intracranial hypertension headache may be indistinguishable from the symptoms of migraine headaches, the presence of pulsatile tinnitus may help with the diagnosis because of the high prevalence of tinnitus in this headache type.
Several possible explanations have been advanced to explain the association of pain with tinnitus. According to Llinas et al, thalamocortical dysrhythmia is responsible for neurogenic pain and tinnitus. They proposed thalamocortical dysrhythmia as a pathophysiological model for the development of γ band activity related to the tinnitus percept. Other researchers believe that tinnitus (similarly to chronic pain) has a peripheral physiological origin, but then the stimulus becomes established in the brain. Gu et al showed that people with tinnitus and normal audiograms demonstrated a reduction in the activity of the auditory nerve, which was then paired with hyperactivity in the auditory brainstem. This suggests a similarity between tinnitus and phantom limb syndrome. Finally, a study by Muhlnickel et al found a strong positive correlation between the subjective strength of tinnitus and the amount of cortical reorganisation, which was similar to their previous findings in phantom limb pain in upper extremity amputees.
Cognitive deficits such as attention and processing speed are also associated with chronic tinnitus. Patients with tinnitus performed worse on the Stroop test compared with people without tinnitus. A study examining selective and divided attention confirmed that tinnitus patients' attention is impacted. Tinnitus patients have slowed cognitive processing speed, even after controlling for IQ and anxiety. Most recently, Das et al did a cross-sectional study of 92 chronic tinnitus patients, objectively measuring cognitive processing speed using the Brain Speed Test (BST). Patients with more severe tinnitus had longer reaction times on the BST. Even after controlling for the composite psychiatric state, the BST score was a significant predictor of tinnitus severity.
Neuropsychiatric Symptoms Associated With Tinnitus
Affective, Anxiety and Personality Disorders
Tinnitus is associated with psychiatric disorders. Marciano et al found that 77% of tinnitus patients met criteria for a psychiatric disorder. They most frequently had affective, anxiety and somatoform disorders (DSMIV-Axis I), but often also had personality disorders (DSM-IV Axis II). This was also seen by Zoger et al, who found that the lifetime prevalence of depressive and anxiety disorders in tinnitus patients was 62% and 45%, respectively. Many studies have shown that Beck Anxiety Inventory Scores and Beck Depression Inventory Scores were significantly higher in tinnitus patients than in normal control subjects. A population study found that emotional exhaustion was a strong predictor of the severity of tinnitus. Also, a decrease in depression was associated with a decrease in tinnitus prevalence. Finally, a few studies looked at a possible association between tinnitus and suicide though this association was confounded by comorbid psychiatric conditions, particularly depression. However, one study found that frequent tinnitus was associated with generalised anxiety disorder but not major depressive disorder.
Patients with tinnitus have higher scores on paranoid ideation, psychotism and hostility. Sometimes, it can be difficult to distinguish between tinnitus and psychotic symptoms, especially in patients with schizophrenia.
Tinnitus has also been described as a somatoform disorder. The WHO found that 42% of the patients with somatisation disorder had tinnitus with autonomic arousal as a common link.
Stress
Studies are also being carried out looking at the effects of stress on tinnitus, as well as tinnitus on stress levels. People who are highly stressed are about as likely to develop tinnitus as people exposed to occupational noise. Exposure to both high stress and occupational noise doubles the chance of developing tinnitus. Another study found a linear association between stress (health-related and/or work-related stress) and the magnitude and duration of tinnitus. Tinnitus sufferers may associate their first awareness of tinnitus to changes in their life, such as divorce, being laid off, sickness in family members, accidents, surgery or having their ears syringed. These events can heighten the brain's arousal, and the tinnitus may be noted cortically. This interaction between reduced auditory sensation and brain compensation might explain why some people are very bothered by their tinnitus and others just adjust to it.
Moreover, allostasis, or the body's ability to adapt to stress, might also be linked to tinnitus. Allostatic load has been shown to affect tissues and organs by causing neuronal atrophy, atherosclerosis, obesity, bone demineralisation and mood disorders, and by decreasing the functioning of the immune system.
Sleep
Difficulty falling asleep is often one of the most common complaints of tinnitus patients. Sleep complaints include delayed sleep, morning awakenings, mid sleep awakenings, morning fatigue and chronic fatigue. To date, three studies have been carried out with polysomnography to evaluate these sleep complaints. Cronlein et al found longer sleep latency in patients with tinnitus compared with patients without tinnitus referred to a sleep centre. However, there were no other differences in objective or subjective complaints of these patients. Burgos et al found that compared with healthy controls, tinnitus patients had worse sleep on subjective and objective complaints (sleep efficiency, total sleep time and number of periods of awakening). Hebert et al found that compared with healthy controls, tinnitus patients had lower subjective sleep quality but had the same objective sleep quality.
Trauma-Associated Tinnitus
Traumatic brain injury (TBI) is a significant cause of tinnitus. In military personnel with TBI, 38% complained of tinnitus. Various types of trauma can precede the onset of tinnitus. These traumas can include noise, brain injuries that injure the auditory pathways, neck injuries and emotional trauma. Interestingly, patients who had trauma-associated tinnitus reported pain symptoms more than non-trauma-related tinnitus patients. They also had higher rates of vertigo and dizziness.
In a study examining the impact of trauma on tinnitus, post-traumatic tinnitus was associated with higher distress levels. Patients with post-traumatic tinnitus may require specialised treatment from those of non-trauma-associated tinnitus patients.
Headache and Pain
Tinnitus can also be associated with certain pain disorders, such as headache. In one case series, 71 out of 112 patients with a primary headache disorder had tinnitus. Up to 26% of basilar migraine patients also have tinnitus. A few patients have been reported to have tinnitus whereby the tinnitus intensity increased only and consistently during headache exacerbations. In these patients, the cutaneous allodynia they reported occurred in parallel with the development of the tinnitus. Volcy et al hypothesised that in patients with headache, the tinnitus may be from spontaneous and aberrant neural activity, may be an allodynic symptom triggered by the trigemino-cervical complex centralisation and/or from cerebral hyperexcitability. Tinnitus may also rarely be seen in migrainous infarction. In idiopathic intracranial hypertension (IIH), 87% of patients described tinnitus. The tinnitus may be caused by compression of the transverse and sigmoid sinuses as well as compression of the eighth cranial nerve. It has been suggested that although the symptoms of idiopathic intracranial hypertension headache may be indistinguishable from the symptoms of migraine headaches, the presence of pulsatile tinnitus may help with the diagnosis because of the high prevalence of tinnitus in this headache type.
Several possible explanations have been advanced to explain the association of pain with tinnitus. According to Llinas et al, thalamocortical dysrhythmia is responsible for neurogenic pain and tinnitus. They proposed thalamocortical dysrhythmia as a pathophysiological model for the development of γ band activity related to the tinnitus percept. Other researchers believe that tinnitus (similarly to chronic pain) has a peripheral physiological origin, but then the stimulus becomes established in the brain. Gu et al showed that people with tinnitus and normal audiograms demonstrated a reduction in the activity of the auditory nerve, which was then paired with hyperactivity in the auditory brainstem. This suggests a similarity between tinnitus and phantom limb syndrome. Finally, a study by Muhlnickel et al found a strong positive correlation between the subjective strength of tinnitus and the amount of cortical reorganisation, which was similar to their previous findings in phantom limb pain in upper extremity amputees.
Cognitive Speed as a Measure of Tinnitus
Cognitive deficits such as attention and processing speed are also associated with chronic tinnitus. Patients with tinnitus performed worse on the Stroop test compared with people without tinnitus. A study examining selective and divided attention confirmed that tinnitus patients' attention is impacted. Tinnitus patients have slowed cognitive processing speed, even after controlling for IQ and anxiety. Most recently, Das et al did a cross-sectional study of 92 chronic tinnitus patients, objectively measuring cognitive processing speed using the Brain Speed Test (BST). Patients with more severe tinnitus had longer reaction times on the BST. Even after controlling for the composite psychiatric state, the BST score was a significant predictor of tinnitus severity.
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