Complications of Peripheral Nerve Surgery

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Chapter 135 Complications of Peripheral Nerve Surgery

Complications involving the peripheral nerves are often difficult to assess and treat, and their consequences may be significant and irreversible. Because of sensory overlap and collateral motor control, even complete nerve lesions may go unrecognized. Before surgical intervention, a thorough clinical and radiologic evaluation is necessary to prevent future problems because injuries to surrounding anatomic structures such as bony fractures may complicate subsequent interventions. In addition, peripheral and central lesions can coexist. Other factors that can contribute to surgical complications include misdiagnosis, inappropriate or unskilled surgical technique, and poor infection control.

Accurate localization of the lesion in the damaged plexus or peripheral elements is essential, and differentiating between complete and partial lesions is also important. The etiology of the injury or disease process is equally important. Atypical clinical presentations can occur from anatomic variants, incomplete lesions, and other medical causes such as diabetes and renal disease. Nondiagnostic clinical findings warrant additional examinations with studies, such as electromyography and radiography.

This chapter summarizes two categories of peripheral nerve complications: (1) the complications that result from peripheral nerve surgery, and (2) the complications of other surgeries and injuries that directly cause peripheral nerve lesions.

Preoperative Assessment for Complication Avoidance

The goals of preoperative assessment include recognition of the pathology, identification of the disease etiology, and selection of an appropriate treatment plan. A number of considerations must be ruled out before any surgical intervention. These complicating factors include immunologic disorders, toxic polyneuropathies, metabolic processes, inflammatory diseases, nutritional deficiencies, drug-induced neuropathies, vasculitides, hormonal etiologies, and connective tissue disorders.1,2

Planning a successful surgery requires a thorough knowledge of normal and variant peripheral nerve anatomy, of the adjacent structures, and of the basic concepts of nerve regeneration and intraneural anatomy.1,312 Thus, an inadequate or misinterpreted preoperative assessment can lead to improper surgical interventions and subsequent complications.1,10,1315

Electrodiagnostic Studies

Electrodiagnostic studies help determine the severity of the nerve injury and establish the baseline of the nerve’s physiologic status and functional integrity.18 In addition, sensory testing with electrophysiologic studies can confirm suspect findings, delineate the problem, or predict the possibility of spontaneous recovery.10,14,19,20 These data can be influenced by a patient’s adaptive response, temperature changes in the pain receptor area, thickness of the myelin sheath, or autonomic conditions.2127

Nerve conduction velocity studies measure the velocity, intensity, and time that it takes an electrical signal to travel the length of the involved nerve. These studies are influenced by the type of instrument being used, the duration and intensity of the stimulation, and the relative distance of the internodes.2830 Conduction velocity normally decreases with age from myelin degeneration and changes in the internodal distances.31 In addition, abnormal conduction test results do not necessarily correlate with a complete loss of sensation because a patient who has a sutured nerve may not fully display nerve conduction but can appreciate light touch.32

Nerve recordings are best measured directly proximal to a nerve lesion, and other interventions may hinder accurate recordings. For example, fluctuations in nerve waveforms can occur if a tourniquet is used or if a nerve is being dissected. Other confounding factors include extensive injuries, neurologic deficits, and the patient’s age and associated medical conditions. Nerve conduction velocity is inconclusive and may demonstrate slow to below-normal values or fibrillations in neuropathies with wallerian degeneration or “dying back” in a portion of an axon.33

Many authors advise using nerve stimulation to ascertain if distal segments are innervated before surgical exploration.3437 However, in the absence of electrical conduction studies, surgical intervention within 3 months of the injury is warranted when there is loss of function in one or more neural elements.10

Complications of Peripheral Nerve Surgery

General Complications

Pulmonary Complications

Pulmonary complications can occur, especially if general anesthesia and lengthy operative time are necessary. These complications include atelectasis, pneumonia, pulmonary embolus, and acute respiratory distress syndrome.53 Preoperative assessment of pulmonary risk factors aids in prevention, and postoperative pulmonary care assists in avoiding unnecessary complications. Specifically, pleural effusion, pneumothorax, hemothorax, and diaphragmatic paralysis can result from brachial plexus or thoracic outlet procedures. Each complication should be appropriately identified based on imaging and clinical judgment and should subsequently be treated appropriately.

Anatomic Variants

Anatomic variants of neural elements and non-neural structures are common and can be a source of iatrogenic injury (Table 135-2). These variations are usually encountered in certain areas, and a thorough knowledge of normal and aberrant anatomy is paramount.1 For example, the nerve to the triceps commonly can arise off the dorsal spinal cord of the brachial plexus in the axilla. The subscapular nerve may arise from the posterior cord as part of a common trunk with the nerve to the subscapularis, or from the axillary nerve itself. The musculocutaneous nerve may arise from the median nerve or can be associated with the tendon of the pectoralis major muscle. Thus, when retracting, dividing, or reapproximating this tendon, the surgeon should pay close attention to preserving this nerve.

Table 135-2 Common Iatrogenic Nerve Injuries

Affected Nerve Procedure
Spinal accessory Lymph node biopsy
Transverse cervical or greater auricular Lymph node biopsy
Brachial plexus Radical neck dissection or mastectomy
Median Carpal tunnel release or removal of ganglion
Radial Arterial puncture or osteosynthesis
Ulnar Removal of ganglion or wrist osteotomy
Superficial radial Kirschner wire placement or removal of ganglion
Anterior interosseous Internal fixation of forearm
Posterior interosseous Osteosynthesis or cast
Sciatic Hip arthroplasty
Femoral Hip arthroplasty or femoral arterial graft
Genitofemoral or ilioinguinal Hernia repair
Tibial Injection or orthopedic procedure
Common peroneal Surgery of the knee or removal of Baker cyst
Sural Vein extirpation
Saphenous Vein stripping

Complications of Surgery for Peripheral Nerve Tumors

Both benign and malignant tumors affect peripheral nerves.5457 These tumors cause motor and sensory symptoms through local mass effect with entrapment as well as compression of adjacent neurovascular structures. Before surgical excision, it is prudent to consider all tumors malignant until confirmed by pathologic examination.

Patients with peripheral nerve tumors should be referred to specialized centers that have experience with peripheral nerve lesions. In general, nerve tumors should be removed when small to decrease the incidence of complications. Biopsies are not recommended in lesions likely to be benign because this may lead to nerve damage or hemorrhage.58

Intraoperative electrodiagnostic studies are mandatory to assess nerve viability and integrity and to determine if nerve grafting is necessary. During these studies, long-acting muscle relaxants should not be used, because these agents interfere with nerve conduction velocity and clinical findings.

Complications of Surgery for Entrapment Neuropathies

Entrapment syndromes are a diverse group of diseases with varying surgical interventions; although most surgical procedures are routine, complications can occur and can result in serious morbidity. For this reason, the specific cause should be determined before entrapment release.

Diagnostic Pitfalls

The preoperative assessment includes a thorough history and physical and electrophysiologic studies; misinterpretation of these findings may lead to delay in therapeutic or surgical interventions.1,13,15 Associated medical conditions may include diabetes, hormonal diseases, connective tissue disorders, rheumatoid disease, arthritis, and metabolic deficiency. In addition, central nervous system pathologies such as syringomyelia, spinal cord lesions, and intracranial masses should be excluded before any surgical intervention.

Misinterpretation of physical signs can also lead to mismanagement. For example, the Hoffman-Tinel sign (a tingling sensation in the distribution of the median nerve over the hand) indicates axonal regeneration, but this sign may be absent in the early and late stages of nerve entrapment. Also, a negative Phalen sign may be due to a lack of pathology or to severe disruption of neural elements.

When a peripheral nerve is entrapped at more than one site such as would be present with carpal tunnel syndrome with cervical spine pathology, it is termed double crush syndrome. With this syndrome, the more distal compression is usually symptomatic. However, when the proximal compression is symptomatic, it is termed reverse double crush syndrome.

Electrodiagnostic studies are often used to confirm peripheral nerve entrapment neuropathies.10,15 Inaccurate results may be due to anatomic variations, associated medical conditions, overlapping sensory innervation, errors in technical skill, and misinterpretation of the results. Examples of overlapping sensory innervation include the Riche-Cannieu anomaly (both branches of the median and ulnar nerves communicate) and the Martin-Gruber anastomosis (the median nerve or the anterior interosseous branch communicates with the ulnar nerve). Awareness of these pitfalls allows for correct interpretation and management.