Impact of Clinico Pathological and Surgical Related Risk Factor in Post Operative Hypoparathyroidism in Total Thyroidectomy Patients.

Abstract

Multiple risk factors have been predicted in post operative hypoparathyroidism in total thyroidectomy patients but none have been clearly defined. Present study aims at evaluating the clinic pathological and surgical impact factors in predicting the risk of post operative hypoparathyroidism in thyroidectomy patients. The study was done in Karpaga Vinayaga Institute of Medical Science and Research Centre where Retrospective prospective cohort study who underwent and undergoing total thyroidectomy with or without central neck dissection for both benign and malignant thyroid disorders during 2014 to 2022 was analyzed. The study has analyzed the various risk factors from clinic pathological and surgical skills of identifying the Inferior thyroid artery at its origin and tracing the branches to the parathyroid gland and evaluating the incidence of hypocalcemia in both study and control groups. Two groups were analyzed during the period 2014 to 2022. The study group was included patients with thyroidectomy where ITA were identified and traced up to the parathyroid gland. They were further classified into category A where both sides ITA were identified and saved, category B where only one side was preserved. In control group, the surgery was done only on basis of capsular dissection and peripheral ligation of vessels close to the gland. Total study participants in our study was 416. The overall prevalence of hypocalcemia in our study was 11.4%. The age, gender and pathological variants were comparable between the two groups. Female preponderance (76%) was seen among both the groups. Among total study subjects who underwent total thyroidectomy 44.8% were having multi nodular goitre, 7.3% toxic goitre, 9.8% follicular adenoma, 30.2% papillary carcinoma and 7.9% follicular carcinoma. In our study benign and malignant thyroid disorders had no significant difference. Prevalence of hypocalcemia among control group 14.5% vs study group 3.8%. We found incidence of hypocalcaemia was comparitively lesser among patients with thyroidectomy alone, than those with unilateral or bilateral CND. Prevalence of hypocalcemia among control group was 33% (45/133) and study group 7% (12/153), when thyroidectomy alone was done. However, with neck dissection in bilateral CND, incidence was 41% (23/56) in study group and 61% (11/18) in control group. In unilateral CND, study and control group had 31% (10/32) and 54% (13/24) which was found to be statistically significant. Parathyroid auto transplantation among the control group (29%) compared to the study group (16%). Bilateral neck dissection and gross extrathyroidal extension and cases with PTG inadvertent removal posed significant risk factors for hypoparathyroidism. The prevalence of immediate hypocalcemia among Cat A, Cat B and control group were 14%, 20.3% and 37.5% respectively and was statistically significant (P < .0001). Symptomatic and Biochemical hypocalcemia at the end of 1week among Cat A, Cat B, and control group was 8%, 12%, and 33.6, & 12.9%, 21% and 30% respectively. Whereas transient hypocalcemia reported among these groups was 1.6%, 5% and 14.6%. Permanent hypocalcemia was < 1% in study group and 4% among control group. We observed that permanent hypocalcemia was high among patients with bilateral neck dissection and auto transplanted PTG. There was no significant statistical difference in hypocalcemia (transient or permanent) among study and control group, but the incidence of hypocalcemia had significantly reduced in both study groups when unilateral or bilateral identification of ITA was done compared to control group. Our hypothesis in this study aims at preserving the branches of ITA supplying PTG distally has greater functional preservation of the parathyroid than conventional technique. This technique also helps us maintaining the plane and capsular dissection if done properly. By trying to preserve the ITA surgeons may acquire better meticulous dissection skills and understanding the anatomical variation of vessels around PTG more precisely which improve the surgical outcome in preventing both transient and permanent hypocalcaemia.