Minimally Invasive Endocrine (Thyroid, Parathyroid, Adrenal) Surgery: Evolution of Operative Techniques, Safety, Effectiveness and Outcomes

The field of endocrine surgery has seen significant changes over the last 10 years. New surgical techniques in thyroid, parathyroid and adrenal surgery characterised by reduced trauma of access and new technology have heralded minimally invasive techniques that have allowed surgeons to perform operations with results similar to traditional approaches whilst offering advantages in recovery time and cosmesis. Surgery is the only definitive cure for primary hyperparathyroidism(PHPT). Sir John Bland Sutton performed the first recorded parathyroidectomy sometime before 1917 but it is Felix Mandl who in 1925 performed the first successful parathyroidectomy for hyperparathyroidism. The surgical strategy for the identification and safe removal of the diseased parathyroid glands has evolved into a safe effective technique with a high success rate in experienced hands. However the arrival of new imaging and surgical technology, an increased understanding of the surgical anatomy and the accumulated experience have been the drivers for developing minimally invasive techniques. Bilateral neck exploration(BNE) with visualisation of all 4 parathyroid glands remains the gold standard treatment of PHPT but only in cases where the localisation studies do not conclusively localise the disease or in cases of persistent or recurrent hyperparathyroidism. Most parathyroidectomies are performed by one of a number of minimally invasive techniques. Such techniques include the endoscopic approach which offers the benefits of magnification, the minimally invasive videoscopically/endoscopically assisted parathyroidectomy (MIVAP) which offers the advantages of the endoscopic approach via a gasless central approach. The focused lateral mini-incision parathyroidectomy is probably the most widely used since it requires no additional instruments, is quick and can be performed under local anaesthetic with equivalent success rates to the other techniques and similar results to the BNE in patients who have localised diseases 97%) with low complication rates. Radioguided parathyroidectomy uses a handheld gamma counter to detect the accumulation of Technetium 99msestamibi that has been injected intravenously, thus guiding the incision point and the dissection. It has also not been widely used possibly due to the use of radiation and the specialised equipment needed. Robotic parathyroidectomy via an axillary approach has been performed by some surgeons in an attempt to abolish the cervical scar. However, the increased cost of the operation and the long learning curve have not yet convinced the mainstream scientific community. The introduction of minimally invasive parathyroid techniques have led to adoption of similar techniques in thyroid surgery. The main advantages of all minimal access thyroidectomy techniques has been to minimise the scar in the neck area. The different techniques can be classified based on whether the incision is made in the neck or away from the neck. Techniques that use a neck incision include the complete endoscopic thyroidectomy with gas insufflation, the video/endoscopic-assisted thyroidectomy without gas insufflation (MIVAT) and the nonendoscopic minimally invasive thyroidectomy via a lateral approach. It should be underlined however that conventional thyroid surgery is now performed via ever diminishing cervicotomy scars with a 4cm incision being now typical for small goitres. The techniques that fall under the second category of no neck incision include the complete endoscopic thyroidectomy with gas insufflation via an axillary or breast approach, the video-assisted thyroidectomy without gas insufflation via an axillary approach (endoscopic or robotic), the facelift robotic thyroidectomy and other experimental approaches such as the trans-oral robotic assisted approach. The MIVAT technique through a neck incision, the video-assisted and the robotic thyroidectomy through a transaxillary approach have been the main focus of interest for most surgeons as they minimise or completely abolish the cervical scar. The disadvantagews of the aforementioned techniques include the need for two assistants for the conventional endoscopic approaches in addition to the operating surgeon and the scrub nurse and a greater cost, increased operating time and a need for careful selection of patients for both conventional endoscopic and robotic apporaches. Nowhere have minimally invasive techniques had greater impact than in surgery of the adrenal gland. The superiority of minimally invasive adrenalectomy to the open approach is overwhelmingly self-evident. It has been shown to be associated with less morbidity, shorter length of stay and earlier return to normal activity. It is now considered the gold-standard technique for benign disease and has undergone numerous modifications since its introduction by Michel Gagner in 1992. These universally involve transabdominal access to the adrenal gland with induction of a pneumoperitoneum and mobilisation of intraabdominal viscera. More recently, an alternative minimally invasive approach-that of retroperitoneoscopic adrenalectomy - has been popularised and involves direct access to the adrenal gland via a true posterior or a postero-lateral approach that obviates the need for entering the peritoneal cavity and the associated visceral mobilisation. Both techniques are now being used in several centres worldwide and recent evidence suggests comparable outcomes with perhaps a reduction in the length of hospital stay in the case of retroperitoneoscopic adrenalectomy. It is clear the Endocrine Surgery offers itself to a variety of minimally invasive techniques that in different combinations and according to local availability and expertise should be in the armamentarium of the Endocrine Surgeon. Fundamental knowledge of these techniques is imperative before embarking on their clinical application and this is where textbooks published by experts in the field have a major role to play.