Parathyroidectomy

Considerations

• • Anatomy 

    • RLN

    • Parathyroid glands

      • Embryology 

        • Superior - derives from 4th branchial pouch

          • Associated with the lateral thyroid anlage / C-cell complex 

        • Inferior - derives from the 3rd branchial pouch 

          • Associated with the thymus anlage 

      • Quantity and size 

        • Four glands - ~ 95%

        • Supernumerary glands - ~ 5% 

        • 20-40 mg 

      • Vasculature  

        • Artery: Inferior thyroid artery supplies both the superior and inferior glands

          • Superior thyroid artery may also supply superior parathyroid branches 

        • Vein: thyroid plexus of veins consisting of inferior, middle, and superior thyroid veins on the anterior thyroid gland 

      • Location

        • Mirror-image symmetry is expected between the right and left sides 

        • Superior

          • Postero-lateral to the superior thyroid pole near the level of the cricothyroidal cartilage junction (articulation) 

          • ~ 1 cm superior to the intersection of the ITA and RLN

          • Sometimes within the thyroid capsule 

          • Sometimes retrolaryngeal or retroesophageal 

        • Inferior 

          • More variable location owing to longer course of descent 

          • Within the postero-lateral aspect of the inferior thyroid pole capsule or 1-2 cm from this aspect of the thyroid 

          • Often associated with thickened fat of the thyrothymic (horn) ligament  

        • In relation to the RLN

          • Mnemonic: S-P A-I R

            • Superior para - Posterior to RLN

              • Deep or dorsal

            • Inferior para - Anterior to RLN

              • Superficial or ventral 

        • Aberrancy

          • Most common aberrant location = anterior superior mediastinum 

      • Appearance

        • Shape - "Flat bean" or "leaf like"

        • Color - Yellow-tan, caramel, or mahogany 

          • Versus the brighter and less distinct surrounding fat 

        • Movement - "the gliding sign" - Discrete masses that glide within the surrounding fat

  • Indications 

    • Primary hyperparathyroidism

      • Etiology

        • Single adenoma (85%)

        • Four gland hyperplasia (10%)

        • Double adenoma (4%)

        • Parathyroid carcinoma (1%)

    • 2004: The NIH Criteria for Parathyroidectomy in Asymptomatic Primary Hyperparathyroidism

      • • Think "Patient, 1-2-3-4-5" 

        • Patient request, or patient is unsuitable for long-term surveillance 

        • Serum Ca > 1 mg/dL above upper limit of normal

        • BMD reduced > 2.5 SD by T-score

        • Cr clearance reduced > 30% for age in absence of another cause

        • 24-urine Ca > 400 mg/dL 

        • Age < 50 years

    • 2009: When is Surgery Indicated for Asymptomatic Primary Hyperparathyroidism?

    • 2009: Guidelines for the Management of Asymptomatic Primary Hyperparathyroidism: Summary Statement from the Third International Workshop

    • Secondary hyperparathyroidism

    • Tertiary hyperparathyroidism

    • Parathyroid carcinoma 

  • Special circumstances

    • MEN 1

    • 2013: Minimally invasive parathyroidectomy provides a conservative surgical option for multiple endocrine neoplasia type 1-primary hyperparathyroidism

    • MEN 2a 

  • Preoperative studies 

    • Ultrasound 

    • Sestamibi

    • SPECT 

    • SPECT / CT

    • Multiphasic (4D) CT

    • MRI 

  • Technique 

    • Concept

      • The technique employed should match the disease pattern

      • The aggressiveness of gland resection should match the disease severity 

        • Remove any suspected adenoma

        • Identify at least one "normal" gland with appropriate ioPTH drop before concluding 

          • If the second gland biopsied is hyperplastic, pursue subtotal (3.5 gland) resection or total resection with auto-transplantation

    • "Minimally invasive" 

    • 2002: Video-assisted parathyroidectomy

    • 2011: Minimally-invasive parathyroid surgery

    • Unilateral exploration

    • Bilateral exploration 

Preparation

• • Pre-op with patient

    • Make sure to go over wound care after surgery

      • Tegaderm off in two days

      • Steri-strips off in one week

  • Equipment 

    • Ultrasound 

    • MedTronic NIM ETT for RLN monitoring 

      • Use the green and white electrode cable from the ETT box (they are longer than the electrodes that are included in the standard facial nerve, etc. box) 

      • Dr. G - Place the green and white electrodes needles (green over white) on the mid chest with the needles pointed UP toward the head and secure with 4 strips of umbilical tape in a criss cross pattern

      • Set the stimulator at 0.5 mAmp with a threshold of 100 uV

    • Tray: General thyroid 

    • Suture: 4-0 Polysorb, 5-0 Biosyn

    • Dressing: Mastisol, Steri-strips, Telfa, Tegaderm (small) 

    • Headlamps x 1-2 

      • Dr. G uses his own battery powered headlamp 

    • Surgical loupes - 2.5x magnification 

  • Intra-operative PTH (ioPTH) 

    • Ask anesthesia to place a peripheral IV specifically for blood draws, the foot is an ideal location

    • Ask the circulating nurse to secure the appropriate blood draw tubes for sending the ioPTH to the lab

      • OAK - green tiger top

      • RCH - lavender top 

    • Notify the lab of all PTH labs sent and ask them to contact the OR once results are available (normal turnaround time is 20 minutes) 

  • Draw a pre-incision PTH

    • Values just above normal are more likely to be a 4 gland exploration

  • Positioning 

    • Supine

    • Head straight toward anesthesia 

    • Both arms tucked 

  • Incision

    • Identify and mark midline at the sternum and cricoid 

    • Mark a 2.5-5 (on average 3) cm midline horizontal incision in natural crease approximately at the inferior margin of the cricoid cartilage 

  • Local anesthesia 

    • 1% Lidocaine with 1:100,000 Epinephrine 

    • Infiltrate 1-3 ml using a 25-27 gauge needle on a 3-5 ml syringe

      • Avoid traumatizing the anterior jugular vein system and causing a hematoma

  • Drapes

    • Square off with towels

    • Split and head drapes

      • Use the head drape as an ether drape: have anesthesia clip to IV poles

Procedure

• • Immediately upon securing the ETT, place the green and white electrodes into the chest with metal ends pointing toward the head, secured with tape 

  • Ultrasound to assess the parathyroid glands, thyroid, vasculature, and assist with incision design 

  • Mark, inject local, prep, and drape

  • Think 

    • Meticulous, bloodless dissection

  • Optional: Cover the incision with a small Tegaderm (make sure there are no air bubbles)

  • Incise the skin with the 15 blade

  • Incise subcutaneous fat and platysma with the Bovie on cut

    • Use the skin hook and peanut for traction

  • Raise subplatysmal flaps in a a diamond pattern using Bovie on cut

    • Stay just above the AJV system

    • Superiorly, raise to the thyroid notch

    • Inferiorly, raise to the sternal notch

  • Place the Weitlaner (2-3 prong)

    • Point the handles toward your assistant

  • Identify the midline raphe

  • Lift your side at the raphe using the Debakey forceps while your assistant lifts opposite you

  • Incise the raphe using Bovie on cut

  • Bluntly dissect to the level just superficial to thyroid capsule

    • Do not Bovie onto the capsule; The goal is to preserve thyroid capsule in order to prevent bleeding

  • Divide the raphe superiorly and inferiorly to expose the thyroid

  • Bluntly dissect the straps from the thyroid lobe using the Miccoli tissue retractor and peanut

    • Key: In general, and especially in thyroid/parathyroid surgery: Develop 3-D retraction

      • Do not flatten out structures, which effectively hides hide the areolar tissue planes and restricts safe dissection

    • Start mid thyroid and move laterally to the carotid 

    • At times, you may need to start lower near the strap sternal attachments where the attachments act as counter traction

    • May use the Bipolar to divide loose areolar tissue at the straps

    • May need to use the Army Navy for larger, deeper necks

    • This is all safe and should be relatively quick 

  • Elevate loose areolar tissue from the carotid to gain wider exposure 

  • May or may not need to divide the middle thyroid vein

  • Usually do not need to divide the inferior pedicle at all

  • Roll and lift the thyroid lobe toward yourself using the peanut

    • Key: do not just press the thyroid lobe against the trachea; You need to pull it up and out toward your chest

  • Once you roll the thyroid, will expose TE groove and area of concern for the RLN

  • Bluntly dissect the ITA, paras, and RLN using the McCabe forceps or Bipolar

    • ITA is typically superficial to RLN 

    • Key: At this point, it's best to have a systematic plan about how you "explore" and subsequently identify both normal and abnormal parathyroids 

  • Identify the parathyroid

    • Superior parathyroid gland is deep to the RLN, may be mid lobe and not at the superior pole

    • Inferior gland is superficial and medial to the RLN

      • Look for the para pedicle and how fat slides over the gland

    • When dissecting the parathyroid, make sure to preserve the blood supply until you’re sure that you’re going to take the gland

      • Dissect medial away from the blood supply

    • Single adenomas have a dark liver look, while 4 gland disease has more of an in between look to it

  • Excise the diseased parathyroid gland(s) 

  • In 10 and 15 minutes, repeat the ioPTH

    • Await at least 50% drop and return to normal range

  • Begin closure, but do not fully close the wound until appropriate ioPTH is confirmed

    • Place the Weitlaner again

    • Approximate the straps at the midline raphe using running 4-0 Polysorb suture leaving and inferior gap

    • Approximate the platysma and deep dermis using buried interrupted 4-0 Polysorb suture

    • Approximate the epidermis using buried interrupted 5-0 Biosyn

  • Again, once the appropriate ioPTH is confirmed, place the dressing

    • Mastisol, Steri-strips in parallel with the incision, Telfa cut to size, small Tegaderm

      • Aalways use small Ttegaderms; If incision is larger, just use mutiple Tegaderms

  • For 4 gland exploration: Obtain an additional ioPTH when closing to assess for need for calcium supplementation

Sample operative report

Findings:

• • Incision size *** cm 

  • Pre-excision ioPTH ***

  • *** minute post-excision ioPTH ***

  • *** RLN identified and stimulated at *** mAmp

  • *** parathyroid gland locations 

  • Performed *** parathyroidectomy

Procedure in Detail:

Patient was brought to the operating room and a time out was performed per operating room policy with all members of the surgical team present.

General anesthesia was induced without difficulty using a Medtronic RLN monitoring endotracheal tube. The electrodes were attached to the NIM monitor and tracing and stimulation were confirmed. A pre-excision ioPTH was drawn. This value returned as ***.

The ultrasound {WAS, WAS NOT:233490} used to evaluate the neck to attempt localization of an abnormal parathyroid gland. ***. A *** cm incision was planned in an appropriate location. The patient was prepped and draped in the standard fashion to encompass all surgical sites.

Reverification was performed prior to incision. Incision was carried through the skin and subcutaneous tissue. Subcutaneous/ subplatysmal flaps were rasied superior and inferior.

The {LEFT:30912} side was explored by retracting the strap muscles off the thyroid gland. The carotid artery was identified and the thyroid gland was retracted medially to expose the tracheoesophageal groove and the cricothyroid joint. The middle thyroid vein {WAS, WAS NOT:233490} ligated.

A {SUPERIOR/INFERIOR:32394} parathyroid gland was noted to be enlarged. This was dissected out and it's vascular pedicle was ligated with bipolar electrocautery. The recurrent laryngeal nerve {WAS, WAS NOT:233490} identified. ***

The {LEFT:30912} side was explored by retracting the strap muscles off the thyroid gland. The carotid artery was identified and the thyroid gland was retracted medially to expose the tracheoesophageal groove and the cricothyroid joint. The middle thyroid vein {WAS, WAS NOT:233490} ligated. ***

A *** min post excision ioPTH was drawn and sent to the lab after not manipulating the surgical bed.

The wound was thoroughly irrigated with warm saline. A valsalva was performed. Any active bleeding was controlled. The surgical incision was closed in layers and a sterile dressing was applied.

The post-excision ioPTH value was ***.

Care was returned to the anesthesiologist who extubated the patient and transferred them to PACU in stable condition.

Post-op

• • As for every surgery, contact call the family in immediate post op period

  • If 4 gland exploration is performed and closing ioPTH is < 10

    • Start Calcium taper

      • 3 grams / day for week 1

      • 2 grams / day for week 2

      • 1 gram / day for week 3

      • 1/2 gram / day for 1 week, then stop 

    • Calcitriol (1,25-dihydroxycholecalciferol or 1,25-dihydroxyvitamin D3) 

      • 0.25-.5 mcg daily or twice daily  

  • Follow-up

    • POD 2 TAV - symptom check, specifically ask about symptoms of hypocalcemia

    • Review the pathology report  

    • Email the Endocrinologist

• Complications 

  • RLN injury

    • Hypocalcemia secondary to hypoparathyroidism 

      • Iowa Protocols: Calcium Management in Thyroidectomy Patients - Hypocalcemia

  • Pharyngeal / esophageal injury 

Pearls & Pitfalls

• • Pearls 

    • Review the imaging and labs 

    • Perform your own ultrasound pre incision in the OR 

  • Pitfalls 

    • If you don't find an obvious adenoma, always examine all identifiable glands prior to excising any one gland  

High-Yield

• • What is the only parathyroid gland disorder in which the superior glands are notably larger than the inferior glands? 

    • Water clear cell hyperplasia 

Links

• eMedicine - Parathyroidectomy

• eMedicine - Minimally Invasive Surgery of the Parathyroid

  • Open Access Atlas - Parathyroidectomy 

• Iowa Protocols - Parathyroidectomy

• Radiopaedia - Parathyroid glands