Tinnitus Blood Flow and Cerebral Venous Congestion

A study of 87 participants using advanced brain imaging has identified a distinct pattern of reduced blood flow in the brains of patients with non-auditory tinnitus linked to venous congestion. The research, led by Lu Liu, Milan Jia, and colleagues at Capital Medical University in Beijing, connects these perfusion changes directly to symptom severity and emotional distress.

Connecting Veins, Blood Flow, and Phantom Sounds

Non-auditory tinnitus (NAT) describes a perception of sound, like ringing or humming, that does not originate from the ear’s auditory system. Instead, it is thought to arise from within the brain or central nervous system. One proposed cause is cerebral venous congestion (CVC), a condition where narrowed or blocked veins in the head—such as the internal jugular vein or venous sinuses—impair the brain’s ability to drain blood properly. The hypothesis is that this backup of blood can reduce the overall flow of fresh, oxygenated blood to brain tissue, a measure known as cerebral blood flow (CBF). Reduced CBF could then trigger neurological symptoms, including tinnitus. The team from Xuanwu Hospital set out to test this by measuring CBF in patients with CVC, with and without NAT.

Measuring Brain Perfusion with Multi-Delay ASL

The researchers conducted a cross-sectional study with 34 patients who had CVC and NAT, 17 patients with CVC but no tinnitus, and 36 healthy controls. To measure CBF, they used a non-invasive MRI technique called multi-delay pseudo-continuous arterial spin labeling (ASL). This method uses magnetically labeled blood water as a tracer to quantify how much blood is delivered to different brain regions per minute. The “multi-delay” aspect allows for adjustment of the arterial transit time, making the CBF measurement more accurate, especially in conditions like CVC where blood flow timing might be altered.

Brain regions were defined using the Anatomical Automatic Labeling atlas. The team then compared whole-brain and regional CBF across the three groups and analyzed correlations between CBF values and clinical data: tinnitus duration, sleep quality (Pittsburgh Sleep Quality Index), anxiety and depression scores (Hospital Anxiety and Depression Scale), and cognitive function.

Left-Sided Blood Flow Reductions Linked to Symptom Severity

The imaging revealed a clear pattern. Patients in the NAT+ group had significantly lower CBF in the left hemisphere and overall cerebrum compared to both the NAT- group and healthy controls. Specific regions with the most pronounced reductions included the left insula, left paracentral lobule, and left precentral gyrus.

These are not random areas. The insula is involved in interoception and emotional processing; the paracentral lobule plays a role in sensorimotor function for the lower limbs; and the precentral gyrus is the primary motor cortex. Further network analysis showed the affected regions belong to major brain networks governing attention, sensorimotor activity, the default mode network (active during rest and self-referential thought), and cerebellar networks.

The clinical correlations were striking. Within the NAT+ group, the degree of CBF reduction was associated with how long a patient had experienced tinnitus. Lower CBF also correlated with poorer scores on sleep quality and depression assessments. This suggests the perfusion deficit is not just a biomarker but may be mechanistically linked to the daily burden of the condition.

Implications for Understanding and Treatment

This study, published in Brain Imaging and Behavior (PMID: 41957332), provides direct imaging evidence supporting the venous congestion model for some forms of tinnitus. It moves the discussion beyond the auditory pathways to broader brain networks affected by compromised vascular health.

The link to sleep and mood symptoms is particularly important. It offers a potential physiological explanation for why these comorbidities are so common in chronic tinnitus sufferers. The findings align with other research showing how hearing-related disorders involve widespread brain networks. For instance, studies on hyperacusis brain changes and brain responses in misophonia vs. hyperacusis also highlight alterations in non-auditory regions like the insula and areas involved in emotional salience.

Practically, this research points to new directions for assessment and intervention. It suggests that for patients with NAT, especially with comorbid sleep or mood issues, evaluation for vascular contributors like venous congestion could be warranted. Treatments aimed at improving cerebral venous drainage or enhancing cerebral perfusion might be explored as part of a targeted management strategy. The authors note that confirmation in larger, longitudinal studies is needed to establish causality and examine how blood flow changes over time.

For patients, this work reinforces that non-auditory tinnitus is a real, physical condition with measurable changes in the brain. It underscores the importance of a comprehensive neurological evaluation that looks beyond the cochlea to understand the full picture of a patient’s symptoms.