Peripheral nerve microanatomy: new insights into possible mechanisms for block success.

Postmortem histology and in vivo, animal-based ultra-high-definition microultrasound demonstrate a complex array of non-communicating adipose tissue compartments enclosed by fascia. Classic nerve block mechanisms and histology do not consider this tissue. Injected local anesthetic agents can occupy any of these adipose compartments, which may explain the significant differences in outcomes such as success rates, onset time, block density, duration of nerve block, and secondary continuous block failure.

Comparative anatomical study of digital block with the WALANT, interdigital, and transthecal techniques.

Introduction: Interdigital block and transthecal block through the flexor sheath are commonly used techniques for the anesthesia of isolated fingers. The wide-awake local anesthetic no-tourniquet technique is a relatively new approach for local anesthesia during finger procedures. The anatomical spread of local anesthetics with the wide-awake local anesthetic no tourniquet technique has not been described adequately.

No evidence of fascicular injury following a low-volume intraneural injection of the median nerve: a cadaveric study.

Background: The test dose or hydrolocation technique allows rapid detection of spread location. Though its primary aim is to enhance safety in peripheral nerve blocks, evidence on the potential risks of an intraneural test aliquot is lacking. We conducted a cadaveric study to evaluate the risk of fascicular injury following a low-volume (<1 mL) intraneural injection of the median nerve.

Neuraxial pathology and regional anesthesia: an education guide to decision-making.

In current clinical practice, spinal anesthesia and analgesia techniques-including epidural and subarachnoid procedures-are frequently executed without imaging like X-ray or epidurography. Unrecognized spinal pathology has resulted in serious morbidity in the context of performing neuraxial anesthesia. Typically, preoperative consultations incorporate a patient's medical history but lack a detailed spinal examination or consideration of recent MRI or CT scans.

Nerve block, nerve damage, and fluid injection pressure: overturning the myth.

Histological and micro-ultrasound evidence rebuffs deep-rooted views on the nature of nerve block, nerve damage, and injection pressure monitoring. We propose that the ideal position of the needle tip for nerve block is between the innermost circumneural fascial layer and outer epineurium, with local anaesthetic passing circumferentially through adipose tissue. Thin, circumferential, subepineural expansion that is invisible to the naked eye was identified using micro-ultrasound, and could account for variability of outcomes in clinical practice.

Refractory primary and secondary headache disorders that dramatically responded to combined treatment of ultrasound-guided percutaneous suprazygomatic pterygopalatine ganglion blocks and non-invasive vagus nerve stimulation: a case series.

In 1981, Devoghel achieved an 85.6% success rate in treating patients with treatment-refractory cluster headaches with alcoholization of the pterygopalatine ganglion (PPG) via the percutaneous suprazygomatic approach. Devoghel's study led to the theory that interrupting the parasympathetic pathway by blocking its transduction at the PPG could prevent or treat symptoms related to primary headache disorders (PHDs).

Identification of spread after deliberate intraneural injection in five mammalian species.

Introduction: This research endeavors to investigate the phenomenon of intraneural spread across distinct locations: subcircumneurium, extrafascicular intraneural, intrafascicular intraneural, and intraperineurium after deliberate intraneural injections across five mammalian species. The study also aims to propose determinants influencing this spread. Furthermore, the investigation strives to ascertain the optimal animal species and needle configuration for extrapolating intraneural injection outcomes to human contexts.

Accuracy of injection pressure measurement at peripheral nerves using high-resolution 40 MHz ultrasound in an anesthetized porcine model.

Background: Fluid injection pressure measurement is promoted as a marker of needle tip position that discriminates between tissue layers. However, clinical ultrasound has insufficient resolution to identify the exact position of the needle tip. Our primary objective was to use 40 MHz ultrasound in anesthetized pigs in order to precisely locate the tip of the needle and measure opening injection pressure in muscle, at epineurium and in subepineurium.

Visceral versus somatic pain: an educational review of anatomy and clinical implications.

Somatic and visceral nociceptive signals travel via different pathways to reach the spinal cord. Additionally, signals regulating visceral blood flow and gastrointestinal tract (GIT) motility travel via efferent sympathetic nerves. To offer optimal pain relief and increase GIT motility and blood flow, we should interfere with all these pathways.