Prediction of Limb Salvage Following Percutaneous Vascular Intervention Using a Composite Tibial Artery Perfusion Score

PURPOSE

To assess a novel tibial artery perfusion score (TPS) for predicting limb salvage in critical limb ischemia (CLI) patients undergoing percutaneous vascular intervention (PVI).

PATIENTS AND METHODS

A consecutive cohort of 115 CLI patients undergoing PVI in 144 limbs from 2011 to 2016 was analyzed. TPS comprised a 27-point scale based on: (1) patent tibial vessels following PVI, (2) severity of calcification of the tibial arteries, (3) presence of an intact pedal arch following intervention, (4) whether or not revascularization was direct or indirect based on the target angiosome, (5) presence of angiosome blush at the completion of index intervention. Limbs were stratified into (1) High [21-27 points], (2) Medium [13-20 points], and (3) Low [0-12 points] TPS. Predictive value of TPS was evaluated using logistic regression and Cox proportional hazards models.

RESULTS

The median follow-up was 15.7 months (range 0.4-69.9 months). Limb salvage in High, Medium, and Low TPS groups was 90.6%, 85.9%, and 55.6%, respectively, as freedom from the composite outcome: (1) limb complication resulting in death, (2) tibial bypass surgery, (3) above-the-knee amputation, or (4) below-the-knee amputation in patients without supratibial disease at the time of PVI. TPS was significantly associated with limb salvage defined as freedom from both the composite outcome and major amputation.

CONCLUSIONS

Based on this preliminary investigation, TPS was associated with limb salvage in CLI limbs, particularly in high-risk limbs. Further validation in a prospective cohort may identify patients with high-risk limbs in need of closer surveillance and earlier reintervention.

LEVEL OF EVIDENCE

Level IV, case series.

Selective Impairment in Frequency Discrimination in a Mouse Model of Tinnitus

Tinnitus is an auditory disorder, which affects millions of Americans, including active duty service members and veterans. It is manifested by a phantom sound that is commonly restricted to a specific frequency range. Because tinnitus is associated with hearing deficits, understanding how tinnitus affects hearing perception is important for guiding therapies to improve the quality of life in this vast group of patients. In a rodent model of tinnitus, prolonged exposure to a tone leads to a selective decrease in gap detection in specific frequency bands. However, whether and how hearing acuity is affected for sounds within and outside those frequency bands is not well understood. We induced tinnitus in mice by prolonged exposure to a loud mid-range tone, and behaviorally assayed whether mice exhibited a change in frequency discrimination acuity for tones embedded within the mid-frequency range and high-frequency range at 1, 4, and 8 weeks post-exposure. A subset of tone-exposed mice exhibited tinnitus-like symptoms, as demonstrated by selective deficits in gap detection, which were restricted to the high frequency range. These mice exhibited impaired frequency discrimination both for tones in the mid-frequency range and high-frequency range. The remaining tone exposed mice, which did not demonstrate behavioral evidence of tinnitus, showed temporary deficits in frequency discrimination for tones in the mid-frequency range, while control mice remained unimpaired. Our findings reveal that the high frequency-specific deficits in gap detection, indicative of tinnitus, are associated with impairments in frequency discrimination at the frequency of the presumed tinnitus.