Ultrasound for Assessing Traumatic Peripheral Nerve Lesions
Ultrasound for Assessing Traumatic Peripheral Nerve Lesions
Ultrasound technology continues to improve with better image resolution and availability. Its use in evaluating peripheral nerve lesions is increasing. The current review focuses on the utility of ultrasound in traumatic injuries. In this report, the authors present 4 illustrative cases in which high-resolution ultrasound dramatically enhanced the anatomical understanding and surgical planning of traumatic peripheral nerve lesions. Cases include a lacerating injury of the sciatic nerve at the popliteal fossa, a femoral nerve injury from a pseudoaneurysm, an ulnar nerve neuroma after attempted repair with a conduit, and, finally, a spinal accessory nerve injury after biopsy of a supraclavicular fossa lesion. Preoperative ultrasound images and intraoperative pictures are presented with a focus on how ultrasound aided with surgical decision making. These cases are set into context with a review of the literature on peripheral nerve ultrasound and a comparison between ultrasound and MRI modalities.
Peripheral nerve injuries can be classified according to their location, mechanism of injury, and completeness of injury. Neurological impairment to the extremities includes motor and sensory loss as well as the potential for the development of neuropathic pain. In the setting of trauma, peripheral nerve lesions often represent one of the most serious long-term sequelae affecting quality of life and causing disability. In a study of 5777 patients with trauma, Noble et al. found a 3% prevalence of traumatic peripheral nerve injuries, 54% of which required surgical intervention. Taylor et al. found a 1.64% incidence of traumatic peripheral nerve injury, with the highest rate of such pathology seen with crush injuries.
The diagnosis and localization of peripheral nerve lesions rely primarily on clinical history and physical/neurological examination. Electromyography (EMG) and nerve conduction studies are useful in confirming the completeness of peripheral nerve injury but cannot differentiate between axonotmesis and neurotmesis. Even the combination of neurological examination and EMG is insufficient for determining the precise extent of nerve damage and whether to proceed conservatively or with surgical repair. Although the absence of significant neurological recovery after a 4- to 6-month observation period is one of the critical determinants for surgical exploration after blunt nerve injury, obtaining preoperative anatomical information of the status of the nerve injury is becoming more important in surgical planning. Critical information to be gleaned from ultrasound includes the following: 1) whether the nerve remains in continuity; 2) length of the gap, if present; 3) presence of a focal neuroma and its location/size; 4) additional areas of nerve injury, such as tandem lesions; 5) degree of adjoining scar tissue; and 6) status of adjoining tissues such as blood vessels and bone.
Direct imaging with MRI and ultrasonography (US) is widely used when evaluating the extent of peripheral nerve injuries. MRI provides high-resolution imaging of peripheral nerves using T2-weighted images in combination with fat and flow suppression, which yield excellent representations of peripheral nerve anatomy. MRI, however, is limited in some centers by the difficulties of access, cost, and time. High-resolution ultrasonography (HRU) has been shown to be a useful tool in the diagnosis of peripheral nerve lesions. HRU can easily identify all the main nerve trunks running in the limbs, including the median, ulnar, and radial nerves in the upper limbs and the sciatic, common peroneal, and posterior tibial nerves in the lower limbs. Review of the literature shows that ultrasound is successful in clearly and accurately demonstrating complete or partial transections, nerve lacerations, epineural hematoma, and neuroma formation as well as the adequacy of postsurgical repair.
In this paper, we present 4 cases in which HRU accurately demonstrated the anatomy and extent of traumatic peripheral nerve injury and guided the surgical management for these patients.
Abstract and Introduction
Abstract
Ultrasound technology continues to improve with better image resolution and availability. Its use in evaluating peripheral nerve lesions is increasing. The current review focuses on the utility of ultrasound in traumatic injuries. In this report, the authors present 4 illustrative cases in which high-resolution ultrasound dramatically enhanced the anatomical understanding and surgical planning of traumatic peripheral nerve lesions. Cases include a lacerating injury of the sciatic nerve at the popliteal fossa, a femoral nerve injury from a pseudoaneurysm, an ulnar nerve neuroma after attempted repair with a conduit, and, finally, a spinal accessory nerve injury after biopsy of a supraclavicular fossa lesion. Preoperative ultrasound images and intraoperative pictures are presented with a focus on how ultrasound aided with surgical decision making. These cases are set into context with a review of the literature on peripheral nerve ultrasound and a comparison between ultrasound and MRI modalities.
Introduction
Peripheral nerve injuries can be classified according to their location, mechanism of injury, and completeness of injury. Neurological impairment to the extremities includes motor and sensory loss as well as the potential for the development of neuropathic pain. In the setting of trauma, peripheral nerve lesions often represent one of the most serious long-term sequelae affecting quality of life and causing disability. In a study of 5777 patients with trauma, Noble et al. found a 3% prevalence of traumatic peripheral nerve injuries, 54% of which required surgical intervention. Taylor et al. found a 1.64% incidence of traumatic peripheral nerve injury, with the highest rate of such pathology seen with crush injuries.
The diagnosis and localization of peripheral nerve lesions rely primarily on clinical history and physical/neurological examination. Electromyography (EMG) and nerve conduction studies are useful in confirming the completeness of peripheral nerve injury but cannot differentiate between axonotmesis and neurotmesis. Even the combination of neurological examination and EMG is insufficient for determining the precise extent of nerve damage and whether to proceed conservatively or with surgical repair. Although the absence of significant neurological recovery after a 4- to 6-month observation period is one of the critical determinants for surgical exploration after blunt nerve injury, obtaining preoperative anatomical information of the status of the nerve injury is becoming more important in surgical planning. Critical information to be gleaned from ultrasound includes the following: 1) whether the nerve remains in continuity; 2) length of the gap, if present; 3) presence of a focal neuroma and its location/size; 4) additional areas of nerve injury, such as tandem lesions; 5) degree of adjoining scar tissue; and 6) status of adjoining tissues such as blood vessels and bone.
Direct imaging with MRI and ultrasonography (US) is widely used when evaluating the extent of peripheral nerve injuries. MRI provides high-resolution imaging of peripheral nerves using T2-weighted images in combination with fat and flow suppression, which yield excellent representations of peripheral nerve anatomy. MRI, however, is limited in some centers by the difficulties of access, cost, and time. High-resolution ultrasonography (HRU) has been shown to be a useful tool in the diagnosis of peripheral nerve lesions. HRU can easily identify all the main nerve trunks running in the limbs, including the median, ulnar, and radial nerves in the upper limbs and the sciatic, common peroneal, and posterior tibial nerves in the lower limbs. Review of the literature shows that ultrasound is successful in clearly and accurately demonstrating complete or partial transections, nerve lacerations, epineural hematoma, and neuroma formation as well as the adequacy of postsurgical repair.
In this paper, we present 4 cases in which HRU accurately demonstrated the anatomy and extent of traumatic peripheral nerve injury and guided the surgical management for these patients.