Minimally invasive parathyroidectomy

ANATOMY
Superior glands from 4th pouch and are constant in position. Adenomas often in tracheo oesophageal groove, posterior
Inferior develop with thymus and are more variable. Adenomas often anterior

Useful landmarks aiding localisation: tracheo-oesophageal groove, prevertebral fascia, inferior thyroid artery and tubercle of zukerkandl

PROCEDURE
Crucial steps: Precise dissection between thyroid lobe and carotid artery, going between strap muscles and SCM, dividing middle thyroid vein.

Supine
Pillow under shoulders
Headlight
Mark Incison 2cm, depends on site (sup or inf gland)
Sup: 1cm sup to neck crease line, lateral to medial margin of SCM
Inf: 1cm inf to neck crease line
LA
Raise skin and platysma flaps with diathermy
Dissect medial border of SCM from lateral border of strap mm. Initially use fat DeBakey forceps then Langenbecks
Open space post to strap mm to expose inf pole of thyroid and trachea. Jugular vein should be retracted laterally
retract strap mm medially and divide middle thyroid vv
Dissect space medial to CCA, continue to prevertebral fascia.
Space b/w thyroid and prevertebral fascia developed with blunt finger dissection as this exposes whole PT bearing area
ITA will help you locate PT and RLN

Inferior adenomas
Mobilise lobe by dividing vessels running to lower pole
RLN is then encountered
Adenoma is often anteroinferior to thyroid lobe, often within a fat envelope
Once identified, dissect in posterolateral avascular plane
divide thyrothymic ligament

Superior adenomas
elevate thyroid lobe superomedially
RLN identified
Adenoma often in relatively posterior plane
position in vertical plane varies widely as it moves inferiorly as it enlarges, but should be withing TO groove
Oesophagus is useful pointer to position of gland
Inferior thyroid artery is often encountered running anterior to adenoma, divide it

Intraoperative frozen section
Intraoperative PTH level

Problems
Renal patients may have scarring in the region of the jugular which may make dissection difficult
Superior gland is above and behind the plane of the RLN and can head back behind the oesophagus into the posterior mediastinum
Inferior glands are often the plane below and in front of the RLN and can track down into thyrothymic ligament, thymus or anterior mediastinum
Should be standard practice to take thymic ligament with your dissection
During thymic dissection follow lower pole of gland to thyrothymic ligament and down to the gland. Several veins run behind or within this ligament to the innominate veins and they should be carefully dissected free before you start tugging away @ the gland: you will encounter significant bleeding