Surgery of the Sympathetic Nervous System

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Chapter 132 Surgery of the Sympathetic Nervous System

Sympathectomy procedures involve interrupting thoracic or lumbar sympathetic pathways to provide relief from autonomically mediated syndromes. Currently the most common disorder treated is essential hyperhidrosis,1,2 but sympathectomies have been used extensively in the past to treat various pain syndromes, including complex regional pain syndrome (CRPS; also known as reflex sympathetic dystrophy), causalgia, vascular insufficiency pain syndromes, and Raynaud phenomenon.36 More recently, pain syndromes have been treated less frequently with ablative sympathectomy procedures because of the limited success with sympathectomy and potential improvement in outcomes with neurostimulation techniques.7,8 This chapter reviews the history, relevant anatomy and physiology, surgical indications, and techniques of the open and closed sympathectomy procedures as well as the more recent endoscopic techniques, with particular regard to perioperative management, complications, and outcomes of the different sympathectomy procedures.

Historical Background

The earliest known investigations of sympathetic nervous system surgery were described by Francois Parfour du Petit in 1727, reporting on the results of sympathectomy in dogs, and Biffi reported similar findings in a doctoral thesis in 1846. Budge and Walker demonstrated the clinical effects of stimulation of the cervical sympathetic chain in humans in 1852. However, it was Claude Bernard, a French physiologist, in a series of articles published in the 1850s describing his observations after sectioning and stimulating the cervical sympathetic chain in rabbits, who provided a clearer understanding of clinical correlates. A well-recognized clinical correlate of Bernard’s experimental observations is known as Horner syndrome, as described by Frederick T. Horner in 1869. However, the first clinical report of a sympathectomy causing the typical ocular changes was reported by Mitchell et al. in 1864, which actually predated Horner’s description by 5 years. This book also coined the term causalgia, a condition that was treated primarily with sympathectomy for many years. Early surgical sympathectomy procedures were promoted by Jaboulay and Johnson, who stripped the periarterial sympathetics to treat exophthalmos, glaucoma, and tic douloureux, as well as vascular insufficiency. One of Jaboulay’s students, Leriche, promoted the use of sympathectomy for ischemic vascular disease; sympathectomy was used frequently in the 1940s for soldiers sustaining nerve injuries in World War II. Subsequently, various sympathectomy procedures reviewed here were refined to treat hyperhidrosis and both ischemic and neuropathic pain syndromes.

Clinical Syndromes

Neuropathic and Ischemic Pain

Chronic pain syndromes9,10 such as causalgia and reflex sympathetic dystrophy (now referred to as CRPS) are thought to arise from peripheral nerve trauma that is usually ill defined. They also include several other related syndromes (e.g., phantom pain, shoulder-hand syndrome, posttraumatic neuralgia). Characteristic symptoms are burning pain, edema, and trophic skin changes in the extremity. Temperature changes are frequently noted in the affected extremity. Ischemic pain syndromes including Raynaud phenomenon and other vasculitic disorders typically have episodes of severe, painful skin blanching, primarily of the hands and fingertips.11 Cold temperature or emotional response may exacerbate these episodes, and extreme cases may result in ischemia and gangrenous ulceration of the digits. The initial treatment is avoidance of cold and administration of α-adrenergic blocking agents, which are useful for less severe cases. Sympathectomy procedures have been used extensively in the past and can provide significant initial relief from severe pain and digital ulcers. However, the long-term outcomes of sympathectomy for relieving the episodic vasospasms associated with chronic pain syndromes and Raynaud phenomenon are less optimal.

Anatomy and Physiology

The autonomic nervous system includes both the sympathetic and the parasympathetic nervous systems. The sympathetic system mediates the “fight-or-flight” responses such as pupillary dilation, tachycardia, bronchial dilation, increased muscle blood flow, and the release of adrenergic agents from the adrenal glands. It is a two-neuron disynaptic system in which responses are mediated through autonomic ganglia, with the ultimate regulation occurring in the hypothalamus. Anatomically, the sympathetic nervous system has outflow in the thoracic and upper lumbar regions of the spinal cord. Preganglionic fibers from the intermediolateral cell column exit the spinal cord through the ventral nerve roots into spinal nerves and enter the paravertebral chain ganglia, coursing through the myelinated white rami communicantes.3,4 Once in the ganglia, the presynaptic neuron can (1) synapse with a postganglionic neuron and exit as a gray ramus to the viscera, (2) synapse with a postganglionic neuron and exit as a gray ramus in a segmental nerve, (3) travel up or down the sympathetic chain, (4) stimulate the adrenal gland, or (5) exit the sympathetic chain in the splanchnic nerves and enter peripherally located ganglia such as the mesenteric ganglia. Postganglionic fibers travel in peripheral nerves or along arteries to reach their target organs. Afferent autonomic fibers travel from receptors though the dorsal spinal roots to enter the spinal cord, where they can trigger reflexes through spinal cord interneurons and efferent autonomic fibers.

The autonomic ganglia are variable in size, number, and location. There are generally three cervical ganglia (superior, middle, and inferior). The lowest cervical ganglia can fuse with the highest thoracic ganglia to form the stellate or cervicothoracic ganglion.3,4 Pupillary dilation occurs as a result of sympathetic output from the spinal cord ciliospinal center of Budge. The preganglionic fibers exit the spinal cord at the T1 and T2 levels and travel through the thoracic, stellate, and middle cervical ganglia to synapse in the superior cervical ganglia; the postganglionic fibers then enter the sympathetic plexus surrounding the carotid artery and travel along the third, fifth, and sixth cranial nerves to enter the orbit and pass through the ciliary ganglion to the pupillary dilators via the long anterior ciliary nerves. A lesion anywhere along this course is manifested by pupillary miosis, anhidrosis (loss of sympathetic innervation to the sweat glands of the face), ptosis (loss of innervation of the superior tarsal musculature), and, occasionally, enophthalmos. The thoracic ganglia correlate with the corresponding thoracic level, as do the upper lumbar ganglia.

Sexual and urinary function are also influenced by the autonomic nervous system.12 Sympathetic efferent innervation to the bladder arises from the lower thoracic and upper lumbar levels. The efferent nerves travel through a series of ganglia in the sacral region, and the postganglionic fibers travel to the vesicular plexus via the hypogastric nerves. There is also sympathetic stimulation involved in both erection and ejaculation in male patients.

Neurochemically, the presynaptic sympathetic neurons are believed to release acetylcholine and peptides that act on muscarinic, nicotinic, or peptidergic receptors of the postsynaptic neurons, which in turn release norepinephrine to achieve stimulatory responses in the innervated organs.

The effects of sympathetic denervation for the treatment of hyperhidrosis presumably arise from interruption of cutaneous sweating and vasoconstriction mediated by the sympathetic nervous system. The mechanisms of a sympathectomy for treating pain and ischemic syndromes are mediated through less well understood pathways from the denervated sympathetic ganglion into the central nervous system, and reducing sympathetic input by a sympathectomy will achieve at least temporary improvement in the pain symptoms.

Preoperative Evaluation

Patients with autonomically mediated syndromes require thorough diagnostic evaluation and aggressive medical treatment before being considered for surgical treatment. A thorough history and physical examination are necessary to begin the evaluation to consider possible underlying metabolic, infectious, or neoplastic disorders, and radiologic evaluation with plain radiographs and either CT or MRI of the thorax and brachial plexus may be needed. However, most preoperative diagnostic studies are limited, and imaging studies have not demonstrated any clear diagnostic information. Psychological evaluation should be considered, particularly in patients with chronic pain disorders.

Diagnostic sympathetic blocks with short-acting anesthetics provide temporary relief, but may cause transient Horner syndrome. Sympathetic blocks are useful indicators that a sympathectomy will be therapeutically successful. Occasionally, repeated blocks may provide temporary relief of pain syndromes that allow rehabilitation to proceed and preclude the need for a sympathectomy. Anesthetic lumbar blocks for diagnostic and therapeutic effects, particularly in lower extremity pain syndromes, may be quite useful.

Medical treatment of autonomically mediated syndromes is theoretically useful and may have potential in limited cases. Medications that produce systemic sympathetic blockade include phenoxybenzamine, which blocks the α-adrenergic receptors.13,14 Alpha blockade is associated with frequent complications, including hypotension, miosis, and loss of ejaculatory function, but it is an effective test treatment for causalgia-type symptoms.

Open Sympathectomy Techniques

Open sympathectomy techniques have been used to treat hyperhidrosis effectively, but have less efficacy for treating pain syndromes, particularly given the need for highly invasive procedures. These approaches do not require specialized endoscopic equipment and techniques. The open techniques are generally known to most practicing physicians.

Cervical and Cervicothoracic Approaches

Operative Techniques

Cervical or cervicothoracic sympathectomy procedures can be performed using several techniques. These include ventral supraclavicular or transaxillary approaches or dorsal costotransversectomy approaches.17,18 Ventral approaches provide good exposure of the sympathetic chain but carry risks of injury to the brachial plexus and pleural cavity.

The most common open approach for upper thoracic and stellate ganglionectomy is the dorsal approach, where a T2 ganglionectomy has been performed for hyperhidrosis and CRPS. The patient is placed in the prone position on the operating table after general anesthesia. A 4- to 5-cm midline incision over T2 and T3 and the paraspinal muscles is retracted to expose and remove the T2 transverse process and proximal rib of T3 (Fig. 132-1), with preservation of the intercostal nerves. The lateral surface of the vertebral body is then exposed by elevating the parietal pleura carefully to expose the sympathetic chain. The ganglia are usually clearly visible and easily dissected from the chain, which is then cauterized with bipolar electrocautery above and below the ganglia, and the ganglion is resected (Fig. 132-2). The ganglion can be sent to the pathology unit for histologic confirmation. A similar procedure is performed on the opposite side for patients with bilateral palmar hyperhidrosis.

In the transaxillary ventral approach described by Atkins,17 the patient is in a lateral position with the arm extended forward. An incision is made in the second intercostal space from the latissimus dorsi to the pectoralis musculature. The pleural cavity is entered and the ribs slowly retracted. The lung is partially deflated, the sympathetic chain is located, and the appropriate ganglion is identified and removed. The transthoracic endoscopic approach developed in recent years has become the most frequently used method today.

The supraclavicular approach is performed with the patient in a supine position with the neck placed in hyperextension. An incision is made above the clavicle and the two heads of the sternocleidomastoid muscle are split. The phrenic nerve is identified and protected, after which the anterior scalene muscle is incised and arterial branches of the subclavian artery are sacrificed. The brachial plexus is then identified and the parietal pleura is dissected from the dorsal chest by blunt dissection. The parietal pleura and subclavian artery are retracted caudally, and the sympathetic ganglia are identified and incised.

Complications

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