Ultrasound Imaging of the Sciatic Nerve

Abstract

The sciatic nerve (SN) is the biggest nerve in the human body and innervates a large skin surface of the lower limb and several muscles of the thigh, leg, and foot. It originates from the ventral rami of spinal nerves L4 through S3 and contains fibers from both the posterior and anterior divisions of the lumbosacral plexus. After leaving the neural foramina, the nerve roots merge with each other forming a single peripheral nerve that travels within the pelvis and thigh. Non-discogenic pathologies of the SN are largely underdiagnosed entities due to nonspecific clinical tests and poorly described imaging findings. Likewise, to the best of our knowledge, a step-by-step ultrasound protocol to assess the SN is lacking in the pertinent literature. In this sense, the aim of the present manuscript is to describe the normal sono-anatomy of the SN from the greater sciatic foramen to the proximal thigh proposing a standardized and simple sonographic protocol. Then, based on the clinical experience of the authors, a few tips and tricks have been reported to avoid misinterpretation of confounding sonographic findings. Last but not least, we report some common pathological conditions encountered in daily practice with the main purpose of making physicians more confident regarding the sonographic “navigation” of a complex anatomical site and optimizing the diagnosis and management of non-discogenic neuropathies of the SN.

Zusammenfassung

Der Nervus ischiadicus (SN „sciatic nerve“) ist der größte Nerv des menschlichen Körpers und innerviert eine große Hautfläche der unteren Extremität sowie mehrere Muskeln des Oberschenkels, des Beins und des Fußes. Er entspringt aus den ventralen Ästen der Spinalnerven L4 bis S3 und enthält Fasern sowohl der hinteren als auch der vorderen Abschnitte des Plexus lumbosacralis. Nach dem Austritt aus den Neuralforamina verschmelzen die Nervenwurzeln miteinander und bilden einen einzigen peripheren Nerv, der im Becken und im Oberschenkel verläuft. Nicht diskogene Pathologien des SN sind aufgrund unspezifischer klinischer Tests und schlecht beschriebener bildgebender Befunde weitgehend unterdiagnostiziert. Ebenso fehlt unseres Wissens ein schrittweises Ultraschallprotokoll zur Beurteilung des SN in der einschlägigen Literatur. Diesbezüglich ist es das Ziel des vorliegenden Manuskripts, die normale Sonoanatomie des SN vom Foramen ischiadicum majus bis zum proximalen Oberschenkel zu beschreiben und ein standardisiertes und einfaches sonografisches Protokoll vorzuschlagen. Basierend auf der klinischen Erfahrung der Autoren wurden dann einige Tipps und Tricks beschrieben, um Fehlinterpretationen bei unklaren sonografischen Befunden zu vermeiden. Abschließend berichten wir über einige häufige pathologische Zustände, die in der täglichen Praxis auftreten, vor allem, um den Ärzten mehr Sicherheit bei der sonografischen „Navigation“ einer komplexen anatomischen Stelle zu geben und die Diagnose und Behandlung von nicht diskogenen Neuropathien des SN zu optimieren.

Keywords

METHODS & TECHNIQUES - ultrasound - sciatic nerve - dynamic ultrasound - THEMES - anatomy - non-discogenic pain

Publication History

Received: 15 February 2023

Accepted after revision: 26 April 2023

Article published online:
13 October 2023

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