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The continuing evolution of diathermy and harmonic scalpel devices is opening the way to minimally invasive thyroid surgery from many new angles
Dr Pall Hallgrimsson
Department of surgery
Endocrine section
University Hospital
Lund, Sweden
In the early days of thyroid surgery, mortality was high. As late as 1850, it was about 40– 50% and the French Academy of Medicine at this time condemned any operative intervention of the thyroid gland. As the 19th century progressed, pioneer surgeons Theodor Kocher and Theodor Billroth changed thyroid surgery from a bloody and life-threatening procedure to a safer and modern surgical intervention, resulting in a dramatic reduction in mortality. Today, thyroid surgery is the most common endocrine surgical operation. It requires experience and technical precision, and it is thought by many in the field to be the most difficult procedure in endocrine surgery.
Operative technique has changed over time. Newer instruments and approaches to the thyroid gland have been reported in recent years in order to improve surgical results and lower the operative time, without increasing the risk of complications.
Nerve monitoring
Nerve monitoring of the recurrent laryngeal nerve was presented several years ago. It has been thought to lower the risk of damage to the recurrent laryngeal nerve and, in addition, provides a functional guidance to the surgeon. The loss of function of the recurrent laryngeal nerve is one of the major postoperative problems in thyroid surgery. The neuromonitoring system (NIM EMG endotracheal tube) allows the surgeon to obtain and interpret neurophysiological signals from the patient during the operation. Many clinics use this as adjunct in thyroid surgery. However, this is controversial, since it has not yet been proven that nerve monitoring does lower the risk for nerve palsy.
New techniques
During the 20th century, monopolar and bipolar coagulation were introduced. These techniques are continuously improving, while devices such as the harmonic scalpel are being developed, which cuts and coagulates simultaneously using a high-frequency mechanical energy. Other novelties are diathermy devices like Bioclamp and the LigaSure sealing system that allows a sutureless vessel ligation. All these new instruments aim to lower the operative time without increasing the complication risk. These instruments have been compared with a conventional operative haemostatic technique like
knot-tying when sealing the larger vessels and it has been shown that these newer instruments do lower the operative time by up 25-30 minutes. The successful introduction of these newer haemostatic devices has led to a newer approach to the thyroid gland. Open thyroid surgery with a 4-6cm long incision in the anterior neck just above the thyroid gland is the treatment of choice. It provides a good and direct exposure to the entire gland and allows a safe dissection with a low morbidity. Until recently, this has been the only technique for thyroid surgery. However, alternative techniques using a minimally-invasive approach have been developed, which use a 2-3cm incision. The minimally invasive technique uses a small camera when making the dissection with special instruments. There are different approaches, but most involve an incision in the neck. An entirely different endoscopic approach, the axillary approach, has recently been reported. This procedure requires extensive dissection and, in that sense, does not belong to the minimally invasive arsenal. Transoral is the latest approach that has been developed in thyroid surgery. Its aim is the
same as in the axillary approaches – to achieve an optimal cosmetic result without increasing the risk for complications. Total thyroidectomies have been performed on pigs and cadavers. This technique provides a short access to the thyroid gland and, according to the experience from animal models, it is possible to identify the recurrent laryngeal nerve bilaterally. Currently, no transoral thyroid surgery has been performed in humans. Nerve monitoring may have a new role in endoscopic – robot-assisted – and transoral thyroid operations, as these access the thyroid gland in a quite different way from open surgery, making the identification of the recurrent laryngeal
nerve more difficult. Generally, thyroid surgery is performed in general anaesthesia with endotracheal intubation with or without a NIM EMG device. However, it is possible to perform a standard open total thyroidectomy in local anaesthesia. It has been shown to be a safe procedure in experienced hands.
Shorter hospital stay
The thyroid gland is one of the most vascularised organs in the body. Traditionally, patients undergoing total thyroidectomies are observed for 24–72 hours before discharge. Short-stay thyroid surgery has, in recent years, been more frequently discussed. In the last decades, we have seen a shorter hospital stay among patients undergoing thyroid surgery partly as a result of improvements in surgical technique. Still, most clinics advocate overnight observation as a minimum after thyroid surgery. Major complications like bleeding and severe hypocalcaemia are still strong arguments against short outpatient surgery. In cohorts of carefully selected patients, however, safe and cost-effective outpatient thyroid surgery has been published – even among patients undergoing total thyroidectomy.
Future developments
In the coming years, we will see further developments of all the new techniques mentioned above and it is possible that thyroid surgery will be conducted through outpatient clinics in the future. The only thing that you really need for a good thyroid operation is an experienced endocrine surgeon.
