Related Experiment Videos
The effects of reduced cerebrovascular circulation on the auditory brain stem response (ABR)
Insights
Decreased carotid blood flow may prolong auditory brain stem response (ABR) wave V latency in middle-aged males. Surgery to restore blood flow did not immediately affect ABR results within one week.
Area of Science:
- Neurology
- Audiology
- Vascular Surgery
Background:
- Reduced cerebral blood flow, particularly in the anterior circulation via the carotid arteries, can impact neurological function.
- The auditory brainstem response (ABR) is a sensitive electrophysiological test reflecting the integrity of the auditory pathway and brainstem function.
- Patients undergoing carotid endarterectomy often have underlying cerebrovascular disease affecting blood supply.
Purpose of the Study:
- To investigate the effect of decreased anterior (carotid) blood flow on auditory brainstem response (ABR) latencies.
- To compare ABR findings in patients with confirmed carotid stenosis to a matched control group.
- To assess the immediate impact of carotid revascularization surgery on ABR parameters.
Main Methods:
- Auditory brainstem response (ABR) testing was performed on middle-aged males with angiographically confirmed decreased carotid circulation.
- Latencies of ABR waves were compared between the experimental group and an age- and sex-matched control group with similar hearing loss.
- ABR results were also compared to normative data and assessed for abnormality; postoperative ABRs were obtained 1 week after endarterectomy.
Main Results:
- Mean absolute latency of wave V was significantly longer in the decreased carotid circulation group compared to controls.
- 29% of patients with reduced anterior circulation showed abnormal ABRs (corrected for hearing loss), versus 0% in the control group.
- No significant changes in absolute or interpeak latencies were observed in postoperative ABR testing within one week of carotid endarterectomy.
Conclusions:
- Confirmed decreased cerebrovascular circulation in the carotid arteries may lead to prolonged absolute latency of wave V in ABR testing.
- ABR can serve as a potential indicator of compromised anterior circulation.
- Carotid revascularization surgery does not appear to immediately alter ABR findings within the first postoperative week.
Abstract:
The effect of decreased anterior (carotid) bloodflow on the auditory brain stem response (ABR) was studied in a group of middle-aged males with angiographically confirmed decreased carotid circulation who were candidates for internal carotid end-arterectomy. Individual and mean latencies from the experimental group were compared to latencies of a control group matched for age, sex, and hearing loss. Mean absolute latency of wave V was significantly longer in the group with decreased anterior circulation when compared to the matched control group. These findings are similar to those from studies examining decreased posterior (vertebrobasilar) circulation. Both the matched control and experimental group were also compared to clinic norms and judged for abnormality. None of the control group ABRs were judged abnormal, after correction for hearing loss, while 29% of the ABRs were judged abnormal from the group with decreased anterior circulation. Postoperative testing was performed 1 week after surgery to determine any immediate effects of revascularization of the ABR. No changes in absolute or interpeak latencies were observed for either ear between pre- and postoperative testing. It is concluded that patients with confirmed decreased cerebrovascular circulation may show prolongation of absolute latency of wave V on ABR testing. Revascularization surgery in these patients appears to have no affect on their ABR within 1 week of surgery.