Anterior transsternal approach for treatment of upper thoracic vertebral tuberculosis

Abstract

Objective:  To study an anterior transsternal approach for treatment of upper thoracic vertebral (T_l‐T₄) tuberculosis (TB).

Methods:  Sixteen patients with upper thoracic vertebral TB underwent anterior decompression and fusion through an anterior transsternal approach. There were nine men and seven women with a mean age of 48.6 ± 2.3 years (range, 37 to 72 years). The involved area included T_l in three patients, T₂ in one, T₂ and T₃ in four, T₃ in two, T₃ and T₄ in four, and T₄ in two. The “inside window of the brachiocephalic artery” was used to access T₁ and T₂ lesions, and the “outside window of the brachiocephalic artery” for T₃ and T₄ lesions, for T2 and T3, both “windows” were used. According to the Frankel grading system, two patients were of Grade A, one Grade B, two Grade C, six Grade D and five Grade E. The kyphosis Cobb's angle ranged from 15°–40° (mean, 22°± 2.5°) preoperatively.

Results:  All patients tolerated surgery wel1. The operation time was 120–150 minutes and bleeding during operation 300–600 ml. The kyphosis Cobb's angle ranged from 10°–25° (mean, 17°± 2.5°) postoperatively. Eight patients with preoperative neurologic deficit had improved. During the follow‐up period, all cases healed without any recurrence. There was no failure of internal fixation. Spinal bone fusion occurred after 3–6 months (mean, 4.2 months) after bone graft in all patients.

Conclusion:  The anterior transsternal approach provides safe and effective access for surgical treatment of upper thoracic TB.

Introduction

Nowadays, the global incidence of tuberculosis (TB) has increased remarkably, especially in developing countries ¹ . Spinal TB is the most common and serious form of skeletal TB ² , ³ . Spinal TB may lead to serious disability and morbidity, especially when it affects the upper thoracic vertebrae. It is difficult to operate on upper thoracic vertebrae TB (T_l‐T₄) because of its special anatomical position. Most of the previously described approaches are posterior, posterior lateral and cervical, but by the authors' surgical experience there are some disadvantages to these approaches. The posterior or posterior lateral approach fails to create an adequate operative space because of the scapula ⁴ . With the cervical approach, it is not easy to decompress the spinal cord at the levels of T₂ or T₃ ⁵ . Nowadays, the anterior transsternal approach is recommended by more and more surgeons because of its advantages of safety and feasibility. In this study, a series of patients with upper thoracic TB treated by anterior transsternal approach is presented.

Materials and methods

Patient data

Sixteen patients underwent surgery through a modified anterior transsternal approach between June 2000 and May 2007. There were nine men and seven women with a mean age of 48.6 ± 2.3 years (range, 37 to 72 years). All patients presented with constitutional symptoms including weakness, malaise, night sweats, low grade fever, weight loss, pain and/or neurological deficits, and all of them underwent laboratory examinations including erythrocyte sedimentation rate (ESR) and C‐reactive protein (CRP), and imaging examinations consisting of X‐ray, CT, and MRI. A definitive diagnosis was made by histological examination of tissue removed at surgery. Of the 16 cases, all had variable degrees of kyphotic deformity, ranging from 15° to 40° (mean, 22.0°± 3.5°). In addition, three cases had intraspinal abscesses, nine had paravertebral abscesses, four had both and twelve had sequestration. Eleven patients had the complication of incomplete paraplegia; according to Frankel's classification two cases were grade A, one grade B, two grade C, and six grade D. All patients underwent anti‐TB treatment by daily oral administration of isoniazid 300 mg, rifampin 450 mg, ethambutol 1200 mg, and pyrazinamide 1500 mg for 3 weeks preoperatively. Patients with malnutrition were given parenteral nutrition to improve their preoperative condition. All clinical outcomes were evaluated by a spinal surgeon who was not part of the therapeutic team, and radiographic data were evaluated as to whether bone fusion had been obtained and the extent of correction of their kyphotic deformity by an independent radiologist. When bone fusion was in question, another radiologist was consulted for confirmation.

Surgical technique

The patient was placed supine on the operating table under general endotracheal anesthesia, and the neck hyperextended and turned to the left side. For better exposure after sternotomy, a rolled towel was placed between the scapulae. A gastric tube was inserted to enable better intraoperative identification of the esophagus. In case of suspected leakage of the thoracic duct, this tube can also be useful for diagnosis. Intravenous antibiotics were given, the preference being for 48 h to 72 h of cephalosporin. All areas in contact with the table were well padded, and then the right anterior neck and chest were prepared and draped in a sterile fashion. A skin incision was made firstly along the inferior third of the anteriomedial part of the right sternocleidomastoid to the mid point of the suprasternal notch, then longitudinally along the midsternal line to a point 5 cm below to sternal angle (Fig. 1). After subperiosteal exposure of the sternum, the retrosternal fat tissue and rest of the thymus were removed by blunt dissection. Then, limited sternotomy and a transverse sternal split performed with a sternal saw (Fig. 2). Bleeding from the sternum was stopped with bone wax, and a retractor inserted.

Figure 1.

The skin incision is made firstly along the inferior third of the anteriomedial part of the right sternocleidomastoid to the mid point of the suprasternal notch, then longitudinally along the midsternal line to a point 5 cm below to sternal angle.

Figure 2.

Limited sternotomy. The manubrium sterni is spilt longitudinally at the midline, then the sternum is spilt transversely at the level of the third right rib by a sternal saw.

For T₁ and T₂ lesions, the inside window of the brachiocephalic artery was used for access, during which the brachiocephalic and right common carotid arteries were gently retracted to the right, and the esophagus and trachea to the left. For T₃ and T₄ lesions, the outside window of the brachiocephalic artery was used, during which the esophagus and trachea were retracted to the left, the basilar part of the right brachiocephalic vein to the right, and the left brachiocephalic vein downwards. For T2 and T3 lesion, a combination of both “windows” was used.

The prevertebral fascia was adequately exposed and opened. Then the TB focus, including any collapsed vertebrae, intervening intervertebral discs and cold abscess, was completely removed through to healthy bleeding bone to obtain spinal cord decompression. After this tissue had been removed, the posterior longitudinal ligament was adequately exposed, allowing complete release of the spinal cord. Then the two immediately adjacent healthy vertebrae were distracted, suitable autologous grafts from the dorsal iliac crest implanted into them and complete interbody fusion achieved with an anterior cervical titanium plate system. After irrigation and hemostasis, a combination of gelatin sponge with streptomycin powder was placed in the surgical area step by step. The manubrium of the sternum was fixed by steel‐wire. Finally, a deep drainage tube was put in place and the incision closed in layers.

All patients were given standard antiTB chemotherapy, including oral administration of isoniazid (300 mg per day), rifampin (450 mg per day), ethambutol (1200 mg per day) and intramuscular streptomycin (0.75 g per day for adults and 0.5 g for children) for 3 months postoperatively. As a second step, isoniazid (300 mg per day), rifampin (450 mg per day) and ethambutol (1200 mg per day) were given orally from 4 months to 9 months. The rehabilitation program included psychotherapy, vocational training, exercise therapy and prevention of complications. All patients returned to our hospital for follow up every 3 months. Decisions as to when the chemotherapy could be stopped and the disease was assumed to be healed were made based on hepatic function and X‐ray image changes.

Results

The operation time was 120–150 minutes (mean, 137 minutes), and blood loss during surgery was 300–600 ml (mean, 400 ml). The postoperative drainage duration was 2–5 days, and the drainage volume 150–500 ml (mean, 300 ml). There was no intraoperative injury to the trachea, esophagus, blood vessels, pericardium or pleura. The results of CT or MRI confirmed complete spinal cord decompression and good recovery of the volume of the vertebral canal postoperatively. Only one patient had a transient hoarse voice due to recurrent laryngeal nerve injury, the symptoms disappearing 2 weeks postoperatively.

The postoperative kyphosis Cobb's angle ranged from 10°–25° (mean, 17°± 2.5°), which was statistically better than that before operation (t = 2.537, P < 0.05). There was no recurrent infection or internal fixation failure in this series. Follow‐up of all patients was successfully completed, the follow‐up time being 6–72 months (mean, 12 months). At the last follow‐up, the neurologic status of eight patients with preoperative neurologic deficit had improved; the other three patients remained at their preoperative level. One patient in Grade A improved to Grade B, one in Grade B improved to Grade C, two in Grade C improved to Grade D, four in Grade D improved to Grade E, while one case in Grade A and two Grade D showed no change. All patients achieved bony spinal fusion within 3 to 6 months (mean, 4.2 months) after surgery judging by spinal X‐ray films. The imaging results of one typical case are shown in Fig. 3.

Figure 3.

A 64‐year old woman with T₃ and T₄ TB achieved good recovery after operation by the anterior transsternal approach. (a) Preoperative CT scan shows the tuberculous focus is at T₃ and T₄. (b) Preoperative MRI shows that the spinal cord is compressed in the corresponding segment. (c) Postoperative CT scan showing that the tuberculous focus has been completely removed and spinal stability reconstructed. (d) Postoperative MRI showing that the spinal cord has been decompressed effectively.

Discussion

TB is still common in today's society, especially in developing countries. Over the past two decades, the incidence of TB has tended to increase ⁶ . According to reports from the World Health Organization, over two billion people suffer from TB. Spinal involvement is the most common form of skeletal TB, accounting for half the cases ⁷ .

Treatment of upper thoracic vertebral TB

Because of the development of antiTB drugs and medical treatment, many patients with spinal TB are cured by chemotherapy. However, spinal TB may cause some complications such as late‐onset neurological deficit, instability and kyphotic deformity, and chemotherapy has a poor effect in some patients, so surgical treatment is sometimes necessary ⁸ , ⁹ , ¹⁰ . Indications for surgery include severe cervical or back pain and/or radicular pain resistant to conservative treatment, neurologic deficits associated with bone destruction, sequestered bone and disc, cold abscess, instability, and progressive deformity ³ , ¹¹ . The aim of surgical treatment is radical debridement, decompression of the spinal cord and reconstruction of spinal stability.

In spinal surgery, the anterior aspect of the upper thoracic spine is a difficult region to approach. Many vital structures, including osseous, articular, vascular and nervous ones, hinder adequate exposure. Posterior or posterior lateral approaches to the upper thoracic spine are commonly used, but have some disadvantages such as destabilization due to resection of ribs or vertebral plates, the need for a long posterior construct to restore stability, and difficulty in exposing the spinal cord and anterior vertebral body to reconstruct spinal stability. Moreover, for patients with spinal TB, the anterior column of the spine is often affected, sometimes resulting in compression of the spinal cord by the inflammatory focus, debris and caseation from the anterior aspect. Accordingly, anterior radical debridement and spinal fusion have been advocated and widely applied. The anterior approach for treating upper thoracic lesions was first attempted in 1957 by Cauchoix and Binet ¹² . Since then, several cases have been reported ¹³ , ¹⁴ , ¹⁵ , ¹⁶ , ¹⁷ , ¹⁸ , ¹⁹ , ²⁰ , ²¹ . The most popular approach is an anterior cervical exposure combined with a partial or complete sternotomy and resection of a portion of the clavicle. This exposure, which is almost intermediate between the esophagus and trachea, and on the lateral side of the left common carotid or brachiocephalic artery, has the disadvantages that ligation and section of the left innominate vein is suppposed to reach T₄ or T₅ and injury to the thoracic duct canoccur.

Previous studies by the present authors have shown that the inside or outside window of the brachiocephalic artery may be a new and feasible approach for T₁‐T₂ or T₃‐T₄ vertebral bodies ²² , ²³ . In this study, 16 patients with upper thoracic vertebral TB underwent anterior decompression and fusion through an anterior transsternal approach, and all of them achieved a good outcome. This indicates that the anterior transsternal approach provides safe and effective access for surgical treatment of upper thoracic TB. In short, this approach makes it is easy to expose lesions in T₂‐T₄ and perform vertebrectomy and complete neurologic decompression. Moreover, as long as plenty of attention is paid to blunt dissection and gentle retraction, injuries of the esophagus, pleura, recurrent laryngeal nerve, vagus nerve, and vessel damage can be avoided.

Complications and their prevention

In the present study, only one patient had a transient voice hoarse due to injury of the recurrent laryngeal nerve, and the symptoms disappeared 2 weeks postoperatively. There were no other complications. However, some matters should be emphasized and observed during surgery: (i) dissect the substernal tissue bluntly avoiding to injury to substernal blood vessel and pleura; (ii) take care not to drag the operation window excessively in order to avoid imbalance in respiration and /or blood pressure as a result of irritating the trachea and vagus nerve and, if these complications do occur, remove the retraction until normal blood pressure and respiration have returned; (iii) be careful when using any instruments to avoid injuring the major blood vessels in the thoracic cavity; (iv) in the absence of specially designed internal fixation for the upper thoracic vertebrae, a cervical anterior Ti‐plate can be used, but it should be bent to the same kyphotic angle as the thoracic spine to obtain better fixation.

In conclusion, the anterior transsternal approach leads the surgeon directly to the lesion, and allows good visualization and adequate operating space for T₁‐T₄ TB lesions. One‐stage surgical management by the anterior transsternal approach for spinal tuberculosis is feasible and effective.

Disclosure

The authors did not receive any outside funding or grants in support of their research for, or preparation of, this work. Neither they nor a member of their immediate families received payments or other benefits, or a commitment or agreement to provide such benefits, from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.