【Overview】.
Hypoparathyroidism is one of the most important complications after thyroid surgery. The incidence of hypoparathyroidism (hypocalcemia) caused by thyroid surgery is reported to be 1% to 32% at home and abroad. Hypoparathyroidism can cause hypocalcemia, the clinical manifestations of which are mainly changes such as numbness of the corners of the mouth, hand and foot twitching, muscle pain and muscle weakness, facial muscle twitching, vertigo, irritability, laryngospasm, chest pain and cardiac arrhythmia. There is a risk of permanent hypoparathyroidism if less than 2 parathyroid glands are preserved in situ intraoperatively. Therefore, it is particularly important to protect the parathyroid glands and their blood supply during thyroid surgery. Post-operative hypoparathyroidism can be classified as temporary or permanent, and the general dividing line is six months after surgery, mainly based on whether symptoms of hypocalcemia need calcium supplementation therapy after surgery, rather than blood calcium levels.
【Cause analysis
1, preoperative factors: the incidence of hypoparathyroidism is significantly higher in those who have re-operated on the thyroid gland than in the initial surgery. The anatomical level is unclear during reoperation, the adhesions are serious, the operation is easy to bleed, the operation is difficult, and the parathyroid glands are easily damaged or mistakenly cut. Patients themselves already have calcium deficiency for other reasons, such as physiological calcium deficiency in women after menopause.
2. Surgical factors.
(1) Misincision of the parathyroid gland is located in the parenchyma of the thyroid gland.
(2) Inability to distinguish the parathyroid glands and mistakenly remove them as fat or lymph nodes together with the thyroid gland.
(3) Recognition of the parathyroid glands but failure to preserve their blood supply.
(4) Contusion of the parathyroid glands by clamping or suturing during hemostasis.
(5) Ligation of the main trunk of the inferior thyroid artery (which accounts for 80% of the blood supply to the parathyroid glands). Traditional thyroid surgery advocates ligation of the inferior thyroid artery trunk away from the lateral aspect of the thyroid gland, which can easily lead to hypoparathyroidism of the inferior thyroid artery blood supply.
(6) In case of bilateral thyroid cancer, bilateral lymph nodes in the central region should be cleared and bilateral inferior pole parathyroid glands should be cleared together.
(7) Do not use a suction device to directly attract the surgical area during intraoperative hemostasis or irrigation to avoid aspiration of the parathyroid glands.
(3) Postoperative factors: After 131I internal radiation therapy for thyroid cancer, permanent impairment of parathyroid function may occur, which may be caused by the damage to the parathyroid glands by 131I radiation.
Preventive measures
1. Intraoperative identification of parathyroid glands should be strengthened: the number and location of parathyroid glands are highly variable. The number of parathyroid glands is generally 2 pairs of upper and lower parathyroid glands with a total of 4 glands, mostly located between the true and false envelope of the dorsal thyroid gland. The location of the superior parathyroid glands is relatively constant, whereas the location of the inferior parathyroid glands is highly variable. Each parathyroid gland has a separate parathyroid artery for blood supply. Most of the superior parathyroid arteries originate from the superior branches of the inferior parathyroid artery, while the inferior parathyroid arteries originate from the inferior pole branches. Careful dissociation from the surface of the thyroid peritoneum preserves the parathyroid glands along with the blood supply. The parathyroid glands have an earthy yellow color compared to fat, with slightly sharpened edges and a flattened shape, and a network of small blood vessels visible on the surface. Some of the parathyroid glands can be hidden in fat, so attention should be paid to differentiation.
2. The parathyroid glands should be protected in situ intraoperatively as far as possible. Although parathyroid autotransplantation is effective, it often cannot fully restore its normal function.
[Solution steps and tips
The upper parathyroid glands are located at the junction of the upper and middle 1/3 of the dorsal side of the thyroid lobe, and all extraperitoneal adipose tissue and loose connective tissue should be freed immediately on the dorsal side of the upper pole of the thyroid gland, which can effectively protect the upper parathyroid glands.
The location of the inferior parathyroid gland is more variable and is usually located near the branches of the inferior thyroid artery. The branches of the inferior artery can be ligated closely to the peritoneum of the thyroid gland, and the fatty tissue can be stripped away together.
If the parathyroid gland cannot be excluded, the specimen can be partially excised and sent for frozen pathology. Once the parathyroid gland is confirmed, it can be immediately cut into thin slices and planted in the sternocleidomastoid muscle or under the skin of the forearm.
4. When clearing the central region bilaterally, the parathyroid glands on the side with small lesions or less lymph node metastasis should be preserved as much as possible. Even the inferior pole parathyroid glands should be carefully identified. If the parathyroid glands are identified, they can be preserved along with their blood supply, which can effectively reduce the occurrence of postoperative calcium deficiency.
[Points to observe after treatment].
1. Hysterical twitching after thyroid surgery is easily misdiagnosed as parathyroid gland injury, mostly seen in young women with knowledge, anxiety and nervousness about surgery, characterized by early onset of hand-foot twitching, normal serum calcium, phosphorus and PTH, ineffective intravenous calcium supplementation, and effective psychological suggestion and sedation treatment.
2, low calcium after thyroid surgery can also be caused by other reasons: such as hemodilution, calcitonin release, “bone starvation” syndrome, etc., not necessarily parathyroid gland damage.
If blood phosphorus is progressively elevated and blood calcium is persistently low, this is a sign of hypoparathyroidism.
4. Calcium supplementation depends on whether there are symptoms of hypocalcemia or serum calcium ion is below 2.1 mmol/L. Oral calcium supplementation can be given first. If the patient has severe hypocalcemia or serum calcium ion is less than 1.8 mmol/L, intravenous calcium gluconate supplementation should be given in varying doses to relieve the symptoms of hypocalcemia. Temporary hypoparathyroidism usually recovers gradually 4 to 6 weeks after surgery.
5. For patients with bilateral thyroid cancer who undergo bilateral clearance in the central region, intravenous calcium supplementation (usually 20 ml of 10% calcium gluconate) can be given on the night of surgery, and both intravenous and oral calcium supplements can be given from the first day after surgery. hospitalization time.
6.Permanent postoperative calcium therapy for permanent hypoparathyroidism is greater than 6 months and requires long-term calcium and vitamin D3 supplementation, and regular intravenous calcium supplementation if necessary.