Thoracoscopic Sympathectomy



Fig. 9.1.
Anatomy of the right thoracic sympathetic chain as seen during thoracoscopic sympathectomy. SVC: superior vena cava.



Multiple aberrant pathways have been described for the thoracic sympathetic chain. The nerve of Kuntz is the most known anatomical variation. It is an alternative sympathetic pathway that directly connects the second or third thoracic ganglia to the brachial plexus [21]. These anatomical variations are of clinical importance to the surgeon because they provide a route for fibers to bypass the sympathetic chain and may be responsible for the recurrence of symptoms after sympathectomy surgery [22, 23].

Because the terminology used to describe this surgical technique has historically been inconsistent and unclear, an effort has been made to establish an internationally agreed upon nomenclature. The International Society on Sympathetic Surgery (ISSS) and STS committee’s consensus was to use a rib-oriented nomenclature. This decision was made because too many patients have mediastinal fat that can obscure clear identification of the specific ganglia and because there are many anatomical variations in the ganglion anatomy [13]. Furthermore, the type of ganglion interruption (clipping, cutting, cauterizing, or removing a segment) should be noted. Thus, if the chain is cauterized on the top of the third rib, the operation should be abbreviated as “cauterized R3, top” [13].



Level of Interruption of the Sympathetic Chain


Historically, palmar hyperhidrosis was treated with transection of the sympathetic chain at R2 and R3, with the addition of R4 if axillary hyperhidrosis was also present. More recent beliefs are that palmar hyperhidrosis can be effectively treated by limiting disruption to a single level, at either R3 or R4, in an effort to minimize side effects and to improve overall quality of life for these patients. Studies have shown that interruption of the sympathetic chain at R4 alone is associated with the lowest incidence of compensatory hyperhidrosis (CH) , the fewest regions/sites of CH, and the lowest frequency of excessively dry hands [24, 25]. Multivariate analysis revealed the most important variable influencing patient satisfaction was palmar over-dryness [25]. The satisfaction rate overall was higher in those with slightly moister hands (more common in the R4 group) as opposed to those with excessively dry hands and significantly higher rates of CH (more commonly in R3 group) [24]. Perhaps more importantly, none of the patients undergoing disruption at the R4 level regretted having the operation [25]. Expert consensus reports that two interruptions in the sympathetic chain at R3 and R4 provide the driest hands at the expense of a higher risk of CH. However, the panel’s recommendation is for an R3 interruption alone, but goes on to state that R4 interruption is an acceptable alternative in order to limit CH [13]. With this in mind, the options of both an R3 or a R4 disruption can be discussed with parents to allow them to make an educated decision, informing them that an R3 interruption alone tends to provide dry hands, though sometimes overly dry, with an increased risk of CH, whereas an R4 interruption alone has a lower rate of CH but the possibility of continuing to have slightly moister hands than the normal child.

For patients with palmar and plantar hyperhidrosis , expert consensus recommends either R4 interruption alone or R4 and R5 interruptions. To yield the driest feet, this panel endorses two interruptions at R4 and R5. However, disruption at R4 alone may reduce the incidence of CH while still providing satisfactory results [13].

In patients with axillary, palmar-axillary, or palmar-axillary-plantar hyperhidrosis , the optimal operation is an interruption at both R4 and R5 [13]. As with palmar hyperhidrosis , some surgeons favor a single level of interruption, at either R4 [26] or R5 [27], for axillary hyperhidrosis. One study demonstrated a 0 % incidence of CH after R5 interruption with no patient regretting having undergone this procedure [27]. Consent requires a careful discussion of the risks and benefits of the varying levels of interruption and the consequences of aggressive or conservative procedures.

ETS can also be used for patients with severe craniofacial hyperhidrosis and must be distinguished from facial blushing as results for this latter condition are less impressive. Expert consensus recommends R3 interruption alone to reduce the risk of CH and Horner’s, which are more common with R2 interruption or R2 and R3 interruptions [13, 27].


Anesthesia


Thoracoscopic sympathectomy is performed under general anesthesia. A single-lumen endotracheal tube (SLT) is sufficient in most cases; however, some surgeons prefer a double-lumen endotracheal tube (DLT) . There are pros and cons to both types of tubes. Single-lung isolation is the main advantage offered by a DLT, which decreases motion within the operative field. However, with the use of CO2 insufflation, positioning, and intermittent breath holding, the lung rarely obscures the surgeon’s view to any significant degree. Some authors have employed bronchial blockers successfully. Furthermore, pediatric airway anatomy may only permit the use of the smaller diameter SLT. Larger diameter tubes may increase the likelihood of a sore throat and transient hoarseness in the immediate postoperative period. In general, a DLT is technically more challenging to place, and proper placement should be confirmed both clinically and bronchoscopically. Ultimately, the decision on the type of endotracheal tube depends on individual preference, age of the child, and discussion between the surgeon and anesthesiologist.


Positioning


The patient lies supine in a semi-Fowler position with the head of the bed elevated at 30–45° (Fig. 9.2). This allows gravity to help retract the upper lobes out of the intended operative field and helps to decompress some of the smaller veins coursing near the rib heads. Rotation of the bed toward the contralateral side can also facilitate in this endeavor. Both arms are abducted to 90 degrees and secured to arm boards so as to expose the axillae. The elbows should be padded to avoid postoperative ulnar neuralgia. A roll is placed behind the shoulders to improve access to the upper sympathetic chain. The supine position provides more than adequate exposure and requires no delay for repositioning and re-preparing the opposite chest. Alternatively, some authors prefer a lateral decubitus position with the operating table extended to widen the intercostal spaces. An axillary roll is placed, and the ipsilateral arm is secured to an elevated arm board at a gentle angle. For this positioning, the surgeon stands ventral to the patient with the assistant and video monitor on the opposite side.

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Fig. 9.2.
Child in semi-Fowler position with arms abducted.


Instruments


This procedure requires an operating theater capable of accommodating standard endoscopic equipment. Basic instruments include a 3-mm rigid thoracoscope (either 0- or 30-degree angled lens), a 3-mm hook electrocautery, a 3-mm endoscopic blunt-tipped curved scissors (mini-Metzenbaum-type) with a monopolar cautery attachment, a 3-mm endoscopic curved dissector, and three 3-mm blunt-tipped trocars. In the unusual event that any significant bleeding is encountered, a suction/irrigation system should be readily available but not opened on the sterile field. Depending on the surgeon’s preference for performing interruption of the sympathetic chain, an endoscopic clip applier or the Harmonic scalpel (Ethicon Endo-Surgery, Inc., Cincinnati, OH) can serve as alternatives to hook electrocautery. However, clip appliers and alternate energy devices are not required and may increase the cost of the case.


Steps of the Surgical Procedure



Port Placement


When performing a bilateral procedure, the skin preparation should include the entire anterior thorax with extension to the posterior axillary lines bilaterally as well as both axillary regions. The side on which the operation is commenced varies according to the surgeon’s preference. Surgeons have described various techniques employing one-, two-, and three-port sites as well as a multitude of locations for their port placement. The postoperative course of patients with a single 12-mm incision versus multiple 3–5 mm incisions is not significantly different. This chapter will focus on a three-port technique with 3-mm trocar sites, as it offers superior visibility with the ability to retract the lung while cutting and cauterizing.

The first 3-mm blunt-tipped trocar is placed in the anterior axillary line within the third, fourth, or fifth intercostal space. Capnothorax is established by insufflating carbon dioxide with a pressure limit of 5 mmHg. This aids in compression and retraction of lung parenchyma while limiting risk of adverse hemodynamic consequences [28]. Next, a 3-mm (or 5-mm to increase illumination and visual quality), 30-degree thoracoscope is introduced. Under direct endoscopic guidance, the second 3-mm blunt-tipped trocar is placed through an incision overlying the fourth, fifth, or sixth intercostal space in the mid-axillary line. The final 3-mm port site is located in the fourth, fifth, or sixth intercostal space near the posterior axillary line.


Exposure of the Thoracic Sympathetic Chain


The sympathetic chain courses cephalad to caudad over the rib heads in the paraspinal region along the posterosuperior aspect of the hemithorax. In the pediatric patient, it is most often visible through the overlying parietal pleura as a whitish, raised (or multinodular) cord. However, the obese child may have a greater degree of fatty tissue in this area, thus concealing the sympathetic chain. On such occasions, the cord can usually be located by “palpation” with an endoscopic instrument.

Next, the surgeon must identify the correct anatomic rib number in order to define the target levels of the sympathetic chain to be interrupted. The first rib can rarely be seen with the thoracoscope, and so the most cephalad rib visualized will be the second rib. The fatty tissue generally obscures the stellate ganglion and first intercostal space in adults though it is sometimes visible in children. If doubt exists as to the rib enumeration, an intraoperative chest radiograph can help to clarify this anatomy.

Endoscopic shears are used to incise the parietal pleura overlying the rib just lateral to the intended level(s) of sympathetic chain interruption (Fig. 9.3). The chain is then carefully freed from its surrounding tissues with sharp dissection when possible and, if needed, electrocautery. To minimize any spread of current toward the stellate ganglion, the surgeon is encouraged to utilize the lowest diathermy setting that can effectively divide the tissue and to employ short “bursts” of cautery current [29]. Fortunately, this is often a fairly avascular plane. However, care must be taken especially in the right chest to avoid avulsing intercostal veins at the T3 and T4 levels, which drain directly into the azygos vein and can bleed significantly when injured [29]. In case of bleeding, hemostasis can often be obtained with direct pressure and/or cautery.

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Fig. 9.3.
Division of the pleura overlying the top of the third rib so as to expose the underlying sympathetic chain along with any accessory nerves of Kuntz.


Interruption of the Sympathetic Chain


Upon exposing the target level(s) of the sympathetic chain, the surgeon must decide on the type of interruption to employ (Fig. 9.4). When performing this procedure for hyperhidrosis, the primary objective is to sever the connections between eccrine sweat glands and the sympathetic chain. A variety of methods for chain disruption have been described in the literature, including resection, transection, ablation, and clipping. However, no clear differences have been found among these techniques [13, 30]. Resecting the chain mandates more dissection and increases the potential for trauma to surrounding tissues without any added significant benefit. Some authors report that clipping has the potential for reversal upon clip removal within 10–14 days of the procedure should CH be intolerable [31], but the authors and others are skeptical of this presumption and do not feel clipping should be considered reversible [13]. According to an STS expert consensus panel, the most important factors for achieving a successful operation are that (1) the correct level of division was accomplished and (2) the nerve ends were separated enough to prevent nerve regrowth [13].

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Fig. 9.4.
After circumferentially freeing the sympathetic chain from surrounding tissues, the chain is interrupted at the desired level (top of the third rib in this figure). We prefer cutting the sympathetic chain sharply with cold endoscopic shears along the upper border of the rib of the corresponding ganglion. Alternatives for disruption of the sympathetic chain include transection with hook electrocautery, clipping, ablation, and resection.

Cutting the sympathetic chain sharply with cold endoscopic shears along the upper border of the rib of the corresponding ganglion has proven an effective method. The bleeding is minimal, and, more importantly, this technique avoids any potential spread of current along the chain toward the stellate ganglion and limits the extent of dissection. Furthermore, dividing the chain at the mid- or upper portion of the rib can reduce risk of unintentional injury to the more inferiorly located intercostal vessels. If the chain is transected using hook cautery, then the cutting current should be utilized, or, alternatively, division with the Harmonic scalpel (Ethicon Endo-Surgery, Inc., Cincinnati, OH) may result in less spread to surrounding tissues. Some surgeons routinely monitor sympathetic tone to the hand in the form of a skin temperature probe or a laser Doppler (to determine palmar blood flow) in an effort to objectively confirm adequate sympathetic chain interruption. We do not employ these latter techniques.

Once the sympathetic chain is interrupted, the two ends should be separated from each other to lessen chance of regeneration. This can be accomplished by tucking the nerve end under an adjacent rib or flap of the parietal pleura. Also, consider cauterizing the distal tip of the divided chain with a “hot” Maryland dissector to aid in this endeavor. Avoid cauterizing the proximal end of the divided chain in order to protect the stellate ganglion.


Lung Re-expansion and Wound Closure


Prior to lung re-expansion, hemostasis is ensured and carbon dioxide insufflation is ceased. To help minimize postoperative pain, an intercostal nerve block using a long-acting local anesthetic (i.e., bupivacaine) can easily be performed at this time under thoracoscopic guidance. After the working ports are removed, a small suction catheter (red rubber catheter, feeding tube, or chest tube) is introduced into the thorax through one of these incisions to facilitate evacuation of the capnopneumothorax. The anesthesiologist also assists in lung re-expansion by providing sustained large tidal volumes. When the surgeon is satisfied that the lung is adequately reinflated, the thoracoscope and suction catheter are removed, and the port sites are closed. If 3-mm incisions were employed, skin adhesive is usually all that is needed to seal the incisions. Local anesthetic is injected at the incision sites.

A similar procedure is then repeated on the opposite side for each desired level of chain interruption.


Post-anesthesia Care Unit


In the recovery room, a routine upright chest radiograph is performed to ensure complete lung re-expansion and exclude a significant residual pneumothorax, which is unlikely. However, small apical pneumothoraces that do not require chest tubes are not uncommon. The carbon dioxide within the chest is typically reabsorbed within 3 h. Most patients tolerate this procedure without issue and are discharged home later that same day on an oral pain regimen. We ask patients to limit their activity for 48 h postoperatively and then to gradually increase to regular activity within a week of surgery.


Pearls and Pitfalls


When opening the parietal pleura or dividing the sympathetic chain, the surgeon should avoid the underlying periosteum because damaging it may cause severe sunburn-like pain in the postoperative period [29]. To protect the stellate ganglion from harm, do not carry out any dissection above the superior border of the second rib. Reduce the settings as well as the use of electrocautery during this procedure whenever possible. Also, sharp division or clipping of the sympathetic chain obviates the potential for inadvertent injury to the stellate ganglion due to spread of an electrical current. When dividing the chain sharply, it is important to separate the ends of the nerve adequately using the “tuck” technique described above.

Anatomical variation of the sympathetic chain can increase the likelihood of operative failure or complications. In the child with palmar hyperhidrosis , some authors advocate division of the pleura overlying the bodies of ribs 2 and 3 at least 2 cm lateral to the chain, and any accessory fibers of Kuntz are severed as they are encountered [3234]. Occasionally, the sympathetic chain may run medial to the rib heads and can increase the probability of an aortic injury in the left chest if caution is not exercised [34]. The surgeon should be aware of the location of the subclavian vessels, azygos vein, hemiazygos vein, thoracic aorta, vagus nerve, and phrenic nerve and take caution to protect them from harm throughout the operation. This procedure usually involves a rather bloodless dissection, but significant bleeding can result from avulsion of intercostal veins draining directly to the azygos vein [20]. Thus, it may be necessary to cauterize or clip some of these vessels while attempting to expose the sympathetic chain. An azygos lobe is an infrequent anatomical variation consisting of an accessory pulmonary lobe at the apex of the lung, which when present may make it difficult or even impossible to accomplish a thoracoscopic sympathectomy [35, 36].

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Oct 25, 2017 | Posted by in PEDIATRICS | Comments Off on Thoracoscopic Sympathectomy
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