Tinnitus and Cerebral Blood Flow Insights

A new brain imaging study from China provides the clearest evidence yet that a specific form of tinnitus is linked to measurable changes in brain blood flow. The research, published in *Brain Imaging and Behavior*, connects reduced cerebral perfusion to non-auditory tinnitus in patients with cerebral venous congestion.

Connecting Vascular Problems to Phantom Sounds

The study, led by Lu Liu, Milan Jia, and colleagues at Capital Medical University, focused on patients with cerebral venous congestion (CVC). This condition involves blockages or narrowing in veins like the internal jugular or cerebral venous sinuses, which can slow the drainage of blood from the brain. Clinicians have long noted that CVC can lead to a range of neurological symptoms, including a form of tinnitus described as non-auditory. Unlike typical tinnitus, which is perceived as coming from the ears, NAT is often described as a humming, pulsing, or rushing sound inside the head.

The team hypothesized that this impaired venous “outflow” might cause a secondary reduction in fresh, oxygenated blood flowing into brain regions critical for sound and sensory processing. To test this, they used a precise MRI technique called multi-delay pseudo-continuous arterial spin labeling (ASL) to measure cerebral blood flow (CBF) in 87 participants.

Methodology: Mapping Blood Flow in Three Groups

The researchers compared three carefully defined groups: 34 patients with CVC and NAT (NAT+), 17 patients with CVC but without tinnitus (NAT-), and 36 healthy controls. This design allowed them to isolate changes specific to the tinnitus symptom, not just the underlying vascular condition.

Using the ASL scans, they quantified blood flow across the entire brain and within 166 specific regions. They then correlated these CBF measurements with clinical data, including tinnitus duration, sleep quality scores, and assessments for anxiety and depression.

A Distinct Pattern of Reduced Blood Flow Emerges

The results revealed a clear and specific pattern. Patients in the NAT+ group showed significantly lower cerebral blood flow compared to both the NAT- patients and healthy controls. The reductions were most pronounced in the left hemisphere of the cerebrum.

Key brain regions with notably diminished perfusion included:
* The **insula**, involved in interoception and emotional processing.
* The **precentral gyrus**, a primary motor control area.
* The **paracentral lobule**, which manages sensation and motor function for the lower limbs.

“When we analyzed the networks these regions belong to, the picture became even clearer,” the authors noted. The affected areas are hubs in the brain’s attention, sensorimotor, default mode, and cerebellar networks. This suggests the vascular issue isn’t random; it disrupts integrated systems that manage focus, body awareness, and internal thought. You can read more about the broader implications of blood flow changes in tinnitus in our article, Tinnitus Linked to Altered Brain Blood Flow.

Blood Flow Correlates with Patient Symptoms

The study went beyond simply identifying reduced blood flow. The researchers found that the degree of reduction was directly associated with the severity of the patients’ clinical experience.

Lower CBF values in the NAT+ group correlated strongly with three factors:
1. **Longer tinnitus duration**
2. **Poorer sleep quality**
3. **Higher scores for depression**

These correlations make a compelling case that the observed brain changes are not just an incidental finding. They appear to be part of the physiological mechanism driving the debilitating symptoms that accompany this condition. The link to emotional dysregulation echoes findings in related disorders; for instance, see how brain responses differ in Affective Sound Processing in Misophonia vs Hyperacusis.

Practical Implications and Future Directions

These findings have several immediate implications. First, they provide a biological basis for non-auditory tinnitus in CVC patients, moving it from a subjective symptom to one with an objective, measurable marker. This could aid in diagnosis and subtyping of tinnitus, which is notoriously heterogeneous.

Second, the strong correlation with sleep and mood symptoms underscores that treating CVC-related tinnitus may require a holistic approach. Improving cerebral venous drainage could potentially address not just the phantom sound, but also the associated depression and sleep disturbances.

Finally, the study points directly to the cerebellar network as being involved. The cerebellum’s role in sensory gating and prediction is an active area of research in hearing disorders, and its inclusion here suggests vascular problems may disrupt these fine-tuning processes.

“The characteristic regional reductions in CBF offer new insights into the venous pathophysiological mechanisms underlying NAT,” conclude Liu, Jia, and the team. They call for larger, longitudinal studies to confirm if treating the venous congestion can reverse the blood flow patterns and alleviate symptoms.

***Source Paper:*** Liu L, Jia M, Li H, et al. Cerebral blood flow alterations in non-auditory tinnitus: implications for cerebral venous congestion pathophysiology. *Brain Imaging Behav*. 2026;20(2):72. doi:[10.1007/s11682-026-01144-8](https://doi.org/10.1007/s11682-026-01144-8). PMID: [41957332](https://pubmed.ncbi.nlm.nih.gov/41957332/).