Increasing the accuracy of spinal needle placement in lumbar punctures using vibroacoustic excitations

Intro Lumbar punctures are a standard procedure for diagnostics or drug administration. However, the correct placement heavily relies on experience. This can increase distress and complications such as post-puncture headaches. The goal of our study was to detect the correct needle placement and facilitate the intervention.

Methods We performed lumbar punctures in five pig cadavers and recorded the vibroacoustic signal (VAS) produced by the needle, as it interacted with the tissue, including ligaments, bone and the dura puncture (DP). To achieve this, we used a microphone prototype, which generates an audible signal from the vibrations. The VAS was filtered and the square of the signal as well as the Continuous Wavelet Transformation (CWT) were used to identify signal characteristics.

Results In 76% of the 75 successful punctures, the experimenter could detect a loss of resistance (LOR). A clear excitation of the VAS could be detected at the time of the DP in 96% of the cases. These events were characterized by a rapid rise and recovery of signal amplitude, followed by free oscillations after the loss of dampening by surrounding tissue when entering the subarachnoid space. The CWT time-frequency spectrum shows spectral lines following the initial excitation corresponding to the free oscillation. These are absent in all other events, making it a key distinction. We were, therefore, able to detect the DP with a higher accuracy than the LOR based on its specific, distinguishable VAS pattern.

Discussion This pattern can be used to train an algorithm to identify a successful DP in real time during the intervention. It also serves as proof of concept, to use the VAS to improve accuracy in a wide range of medical applications such as operating tools and puncture devices.

Publication History

Article published online:
19 April 2024