Long-term reactions to pulsatile tinnitus are marked by weakened short-range functional connectivity within a brain network in the right temporal lobe

Altered functional connectivity of the default mode network in non-arteritic anterior ischaemic optic neuropathy

The functional connectivity of the default mode network is important in understanding the neuro-pathophysiological abnormalities in patients with non-arteritic anterior ischaemic optic neuropathy. Independent component analysis can effectively determine within and between network connectivity of different brain components. Therefore, in order to explore the association between the default mode network and other brain regions, we utilized independent component analysis to investigate the alteration of functional connectivity of the default mode network. Thirty-one patients with non-arteritic anterior ischaemic optic neuropathy and 31 healthy controls, matched for age, sex and years of education, were recruited. For patients and healthy controls, functional connectivity within and between the default mode network and other brain regions were evaluated by independent component analysis. Compared with healthy controls, patients with non-arteritic anterior ischaemic optic neuropathy showed reduced functional connectivity within the default mode network in the right cerebellar tonsil and left cerebellum posterior lobe and increased functional connectivity in the left inferior temporal and right middle frontal gyri. Furthermore, patients with non-arteritic anterior ischaemic optic neuropathy showed reduced functional connectivity between the default mode network and other brain regions in the left cerebellar tonsil and increased functional connectivity in the right putamen, left thalamus, right middle temporal and left middle frontal gyri. In conclusion, negative correlations between several clinical parameters and functional connectivity of the default mode network were observed. The study contributes to understanding the mechanism of functional reorganization in non-arteritic anterior ischaemic optic neuropathy.

Using ALE coordinate-based meta-analysis to observe resting-state brain abnormalities in subjective tinnitus

The origin of tinnitus remains a topic of discussion; however, numerous resting-state functional magnetic resonance imaging (rsfMRI) studies interpret it as a disruption in neural functional connectivity. Yet, there's notable inconsistency in the resting-state data across these studies. To shed light on this discrepancy, we conducted a meta-analysis of extant rsfMRI studies, aiming to identify potential regions that consistently signify core abnormalities in individuals with tinnitus.

METHODS

A systematic search on MEDLINE/PubMed, Google Scholar, and Scopus databases was performed to identify rsfMRI studies on tinnitus published up to October 2022. Coordinates related to the amplitude of low-frequency fluctuation (ALFF) and regional homogeneity (ReHo) brain maps that showed significant differences between tinnitus patients and controls were extracted. Meta-analysis was performed using the activation likelihood estimation method. Data were included from 17 rsfMRI studies that reported a total of 63 distinct foci in ALFF and 46 foci in ReHo.

RESULTS

Our meta-analysis revealed several regions where tinnitus patients demonstrated increased ALFF and ReHO values, both individually and collectively, when compared to control subjects. These regions encompassed the insula, middle temporal gyrus, and inferior frontal gyrus on both sides. Additionally, increased activity was also noted in the cerebellum posterior lobe bilaterally and the right superior frontal gyrus.

CONCLUSIONS

This meta-analysis demonstrates a unique pattern of resting-state brain abnormalities involving both the auditory and non-auditory brain regions as neuroimaging markers, which helps understand the neuro-pathophysiological mechanisms of tinnitus.

Modulations of resting-static functional connectivity on insular by electroacupuncture in subjective tinnitus

Objective

To explore the modulations of electroacupuncture in subjective tinnitus (ST) by comparing the difference of functional connectivity (FC) in ST patients and healthy volunteers between the insular (INS) and the whole brain region.

Methods

A total of 34 ST patients were selected into electroacupuncture group (EG) and 34 age- and sex-matched normal subjects were recruited into control group (CG). The EG received acupuncture at SI19 (Tinggong), GB11 (Touqiaoyin), TE17 (Yifeng), GV20 (Baihui), GV15 (Yamen), GV14 (Dazhui), SJ13 (Zhongzhu), among which the points of SI19 and GB11 were connected to the electroacupuncture instrument with the density wave of 2/50 Hz, and 3 treatments per week for 10 sessions in total. The severity of tinnitus was evaluated by Tinnitus Handicap Inventory (THI), the hearing status was recorded using pure tone audiometry, and resting-state functional magnetic resonance imaging (rs-fMRI) was performed on the brain before and after treatment, the CG received no intervention yet only rs-fMRI data were collected.

Results

With the electroacupuncture treatment, the total THI score, average air conduction threshold of patients of EG were significantly lower than before (p < 0.01), and the total effective rate was 88.24%. Compared with CG, FC of ST patients between INS and left superior temporal gyrus and right hippocampal significantly decreased before treatment, while FC of ST patients between INS and right superior frontal gyrus, left middle frontal gyrus and right anterior cuneus significantly decreased after treatment (voxel p < 0.001, cluster p < 0.05, corrected with GRF). FC of ST patients between the INS and right middle frontal gyrus, left superior frontal gyrus and right paracentral lobule showed a significant decrease after treatment (voxel p < 0.001, cluster p < 0.05, corrected with GRF). In addition, THI score in EG was negatively correlated with the reduction of FC value in INS-left superior frontal gyrus before treatment (r = -0.41, p = 0.017). Therefore, this study suggests that abnormal FC of INS may be one of the significant central mechanisms of ST patients and can be modulated by electroacupuncture.

Discussion

Electroacupuncture treatment can effectively reduce or eliminate tinnitus symptoms in ST patients and improve the hearing by decreasing FC between the INS and the frontal and temporal brain regions.

CT evaluation of unilateral pulsatile tinnitus with jugular bulb wall dehiscence

OBJECTIVES

To investigate the imaging features of unilateral pulsatile tinnitus (PT) with jugular bulb wall dehiscence (JBWD).

METHODS

Computerized tomography angiography images of unilateral PT patients were reviewed between 2019 and 2021. Thirty-one symptomatic JBWD patients without sigmoid sinus wall dehiscence (SSWD) were included. Thirty-eight patients with SSWD were used as the control group. The prevalence of JBWD was calculated. The area and height of the jugular bulb, the extent of dehiscence, the presence of jugular bulb diverticulum, posterior condylar emissary vein (PCEV), oblique occipital sinus (OOS), venous outflow laterality (VOL), the degree of transverse sinus stenosis (TSS), and the pituitary height to sella turcica ratio were compared between the two groups.

RESULTS

The prevalence of JBWD was 12.1%, and JBWD was established as a causative diagnosis in 5.0% of unilateral PT patients. There were no statistical differences in the gender, symptomatic side, or VOL between the two groups. The area of the jugular bulb was larger and the height was higher (p_area < 0.001, p_height = 0.005). The prevalence of jugular bulb diverticulum was higher in the JBWD group (p = 0.002). The degree of symptomatic TSS was less severe (p < 0.001), and the prevalence of bilateral TSS was lower in the JBWD group (p < 0.001). The pituitary height to sella turcica ratio was greater (p = 0.004), the prevalence of PCEV (p = 0.014) was lower, and OOS (p = 0.015) was greater in the JBWD group.

CONCLUSIONS

The correlating factors of PT with JBWD and PT with SSWD are significantly different. These findings can further facilitate early and efficient PT treatment.

KEY POINTS

• The incidence of jugular bulb dehiscence (JBWD) accounted for approximately 12.1% in pulsatile tinnitus (PT) patients, and JBWD was established as a causative diagnosis in 5.0% of PT patients. • PT required large blood flows and abnormal flow patterns, whether in JBWD or sigmoid sinus wall dehiscence groups. • JBWD causing PT has some unique characteristic findings on CT.

Altered Neurovascular Coupling in Unilateral Pulsatile Tinnitus

Objective

Altered cerebral blood flow (CBF) and regional homogeneity (ReHo) have been reported in pulsatile tinnitus (PT) patients. We aimed to explore regional neurovascular coupling changes in PT patients.

Materials and Methods

Twenty-four right PT patients and 25 sex- and age-matched normal controls were included in this study. All subjects received arterial spin labeling imaging to measure CBF and functional MRI to compute ReHo. CBF/ReHo ratio was used to assess regional neurovascular coupling between the two groups. We also analyzed the correlation between CBF/ReHo ratio and clinical data from the PT patients.

Results

PT patients exhibited increased CBF/ReHo ratio in left middle temporal gyrus and right angular gyrus than normal controls, and no decreased CBF/ReHo ratio was found. CBF/ReHo ratio in the left middle temporal gyrus of PT patients was positively correlated with Tinnitus Handicap Inventory score (r = 0.433, p = 0.035).

Conclusion

These findings indicated that patients with PT exhibit abnormal neurovascular coupling, which provides new information for understanding the neuropathological mechanisms underlying PT.

Diploic vein as a newly treatable cause of pulsatile tinnitus: A case report

BACKGROUND

Pulsatile tinnitus (PT) is an annoying sound that can be eliminated with targeted treatment of the cause. However, the causes of PT have not been fully elucidated.

CASE SUMMARY

A 38-year-old woman with right-sided objective PT underwent preoperative computed tomography arteriography and venography (CTA/V). A 3.8 mm vine diploic vein (DV), which passed through the mastoid air cells posteriorly in a dehiscent canal and was continuous with the transverse-sigmoid sinus, was thought to be the causative finding. Four-dimensional flow magnetic resonance (4D flow MR) imaging showed that the blood in the DV flowed toward the transverse-sigmoid sinus. The closer the blood was to the transverse-sigmoid sinus, the higher the velocity. No vortex or turbulence was found in the DV or adjacent transverse sinus. The sound was eliminated immediately after ligation of the DV with no recurrence during a three-month follow-up. No flow signal of the DV was noted on postoperative 4D flow MR.

CONCLUSION

A DV may be a treatable cause of PT. CTA/V and 4D flow MR could be utilized to determine the morphological and hemodynamic characteristics of the DV.

[Tinnitus: clinical and pathogenetic aspects]

The article discusses the pathogenetic and clinical features of tinnitus. It is emphasized that various causes contribute to the appearance of tinnitus, including somatic diseases, excess body weight, iatrogenies, otological diseases with an outcome in hearing loss. The anatomical and physiological features of the structure of the central part of the auditory system are considered. It is suggested that the occurrence of tinnitus is associated with the processes of maladaptive neuroplasticity caused by pathological changes in the neuronal activity of cortical structures of the CNS, and not with changes in the peripheral part of the auditory analyzer - the structures of the cochlea. The results of recent studies, including those using functional neuroimaging methods, indicate the significance of cortical connection disorders (human connectome) in patients with tinnitus. In patients with tinnitus, there are changes in regional neuronal activity and connections not only in the auditory cortex, but also in areas not directly related to the analysis of auditory afferentation. Thus, tinnitus can be considered as one of the variants of dysfunction of the human connectome, triggered primarily from the «auditory input».

Bone remodeling in sigmoid sinus diverticulum after stenting for transverse sinus stenosis in pulsatile tinnitus: A case report

BACKGROUND

Pulsatile tinnitus (PT) is a potentially disabling symptom that has received increasing attention. Multiple causes of PT have been confirmed by targeted treatment. However, dynamic changes of related structures in PT patients with multiple causes after stenting for ipsilateral transverse sinus stenosis (TSS) have not been previously reported. We report such a case and present postoperative computed tomography venography (CTV) follow-up findings to demonstrate the decreased sigmoid sinus diverticulum and bone remodeling.

CASE SUMMARY

A 45-year-old man suffered from left-sided PT for 15 years that was occasionally accompanied by headache and dizziness. Pre-operative CTV revealed left-sided sigmoid sinus wall anomalies (SSWAs), TSS, outflow dominance, large posterior condylar emissary vein, and an empty sella turcica. A cerebrospinal fluid pressure of 270 mmH₂O was further detected. The sound disappeared immediately after stenting for ipsilateral TSS, with no recurrence during 2 years of follow-up. After the procedure, the patient underwent four consecutive CTV examinations. The diverticulum decreased 6 mo after the procedure with new bone remodeling. The density of the remodeled bone was further increased 1 year later, and a hardened edge was formed 2 years later.

CONCLUSION

PT associated with SSWAs, TSS, and idiopathic intracranial hypertension can be cured by stenting for TSS alone. And bone remodeling around SSWAs is a more significant finding.

The Neural Mechanisms of Tinnitus: A Perspective From Functional Magnetic Resonance Imaging

Tinnitus refers to sound perception in the absence of external sound stimulus. It has become a worldwide problem affecting all age groups especially the elderly. Tinnitus often accompanies hearing loss and some mood disorders like depression and anxiety. The comprehensive adverse effects of tinnitus on people determine the severity of tinnitus. Understanding the mechanisms of tinnitus and related discomfort may be beneficial to the prevention and treatment, and then getting patients out of tinnitus distress. Functional magnetic resonance imaging (fMRI) is a powerful technique for characterizing the intrinsic brain activity and making us better understand the tinnitus neural mechanism. In this article, we review fMRI studies published in recent years on the neuroimaging mechanisms of tinnitus. The results have revealed various neural network alterations in tinnitus patients, including the auditory system, limbic system, default mode network, attention system, and some other areas involved in memory, emotion, attention, and control. Moreover, changes in functional connectivity and neural activity in these networks are related to the perception, persistence, and severity of tinnitus. In summary, the neural mechanism of tinnitus is a complex regulatory mechanism involving multiple networks. Future research is needed to study these neural networks more accurately to refine the tinnitus models.

CT venography correlate of transverse sinus stenosis and venous transstenotic pressure gradient in unilateral pulsatile tinnitus patients with sigmoid sinus wall anomalies

Objectives

To investigate the correlation between transverse sinus stenosis (TSS) and transstenotic pressure gradient (TPG) in unilateral pulsatile tinnitus (PT) patients with sigmoid sinus wall anomalies (SSWA).

Methods

Fifty-seven patients with unilateral venous PT were retrospectively included. All of them underwent CT venography and catheter manometry, accompanied with SSWA. The degree, length, shape (intrinsic/extrinsic/dysplasia), location (proximal/middle/distal, referring to the relative position of TSS and the Labbé vein junction) of TSS, the types of SSWA (dehiscence/diverticulum), and the degree of transverse sinus outflow laterality were assessed, and the correlations with ipsilesional TPG were analyzed.

Results

The mean value of ipsilesional TPG was 7.61 ± 0.52 mmHg. The degree and length of ipsilesional TSS were positively correlated with TPG (p < 0.001, p’ < 0.001), respectively. TPG was significantly larger in patients with contralateral transverse sinus dysplasia than those without (p = 0.023) and significantly smaller in patients with ipsilesional sigmoid sinus diverticulum than those with isolated dehiscence (p = 0.001). No statistical difference in TPG was shown between ipsilesional TSSs of different shapes or locations (p > 0.05). No correlation was noted between the degree of ipsilesional transverse sinus outflow laterality and TPG (p = 0.051). Stepwise linear regression indicated that the degree (β = 9.207, 95% CI = 3.558–14.856), length (β = 0.122, 95% CI = 0.025–0.220) of ipsilesional TSS, and contralateral transverse sinus dysplasia (β = 1.875, 95% CI = 0.220–3.530) were significantly correlated with TPG (R² = 0.471).

Conclusions

The degree, length of ipsilesional TSS, and contralateral transverse sinus dysplasia may be used to predict TPG in unilateral PT patients with SSWA.

Key Points

• CT venography may act as a screening tool to help low-probability unilateral pulsatile tinnitus (PT) patients with sigmoid sinus wall anomalies (SSWA) avoid invasive catheter manometry.

• The degree and length of ipsilesional transverse sinus stenosis (TSS) are positively correlated with transtenotic pressure gradient (TPG) in unilateral PT patients with SSWA.

• Ipsilesional TPG is larger in unilateral PT patients with contralateral transverse sinus dysplasia than those without and is smaller in unilateral PT patients with sigmoid sinus diverticulum than those with isolated dehiscence.

Why does unilateral pulsatile tinnitus occur in patients with idiopathic intracranial hypertension?

PURPOSE

To investigate the relevant factors of unilateral pulsatile tinnitus (PT) in patients with idiopathic intracranial hypertension (IIH) using CT.

METHODS

CT angiography images of IIH patients with unilateral PT (n = 19), without PT (n = 13), and controls (n = 32) were reviewed. The characteristics including transverse sinus stenosis (TSS), venous outflow laterality (VOL), sigmoid sinus wall dehiscence (SSWD), and sigmoid sinus diverticulum (SSD) were quantitatively or/and qualitatively detected. VOL was compared between the symptomatic side of IIH patients with PT and the larger side of IIH patients without PT and the controls. TSS, SSWD, and SSD were compared between the symptomatic side of IIH patients with PT, and both sides of the latter two groups.

RESULTS

There was no statistical difference in body mass index or cerebrospinal fluid pressure between IIH patients with and without PT. The prevalence of TSS was significantly higher in IIH patients than that in the controls (p = 0.000), but TSS had no correlation with PT within IIH patients. The prevalence of SSWD successively decreased in IIH patients with PT, without PT, and the controls, with significant differences between each two of three groups (p = 0.000, p' = 0.000, p″ = 0.031). The proportion of VOL and the prevalence of SSD were significantly larger in IIH patients with PT than in the latter groups respectively (p_VOL = 0.005, p'_VOL = 0.000; p_SSD = 0.040, p'_SSD = 0.000). All SSDs in IIH patients with PT were accompanied with SSWD.

CONCLUSION

The dominant VOL and ipsilateral SSWD with/without SSD may be correlated with the occurrence of unilateral PT in IIH patients.

Chronic tinnitus and the limbic system: Reappraising brain structural effects of distress and affective symptoms

Chronic tinnitus has been associated with brain structural changes in both the auditory system as well as limbic system. While there is considerable inconsistency across brain structural findings, growing evidence suggests that distress and other non-auditory symptoms modulate effects. In this study we addressed this issue, testing the hypothesis that limbic changes in tinnitus relate to both disease-related distress as well as co-morbid psychopathology. We obtained high-resolution structural magnetic resonance imaging (MRI) scans from a total of 125 subjects: 59 patients with bilateral chronic tinnitus (29 with a co-morbid psychiatric condition, 30 without), 40 healthy controls and 26 psychiatric controls with depression/anxiety disorders (without tinnitus). Voxel-based morphometry with the CAT12 software package was used to analyse data. First, we analysed data based on a 2 × 2 factorial design (tinnitus; psychiatric co-morbidity), showing trend-level effects for tinnitus in ROI analyses of the anterior cingulate cortex and superior/transverse temporal gyri, and for voxel-based analysis in the left parahippocampal cortex. Multiple regression analyses showed that the parahippocampal finding was mostly predicted by tinnitus rather than (dimensional) psychopathology ratings. Comparing only low-distress tinnitus patients (independent of co-morbid conditions) with healthy controls also showed reduced left parahippocampal grey matter. Our findings demonstrate that depression and anxiety (not only subjective distress) are major modulators of brain structural effects in tinnitus, calling for a stronger consideration of psychopathology in future neurobiological and clinical studies of tinnitus.

•

Chronic tinnitus is associated with high psychiatric co-morbidity and distress.

•

Parahippocamal grey matter is associated with tinnitus rather than distress.

•

Psychiatric co-morbidity modulates tinnitus-related structural patterns.