The Use of Dexamethasone in Total Thyroidectomy to Improve Voice Outcome and Hypocalcaemia

Thyroidectomy is a standard procedure for benign and malignant pathologies of the thyroid gland. Each year, some 100 total thyroidectomies are performed in Kowloon East Cluster, Hospital Authority, Hong Kong. Total thyroidectomy is associated with voice dysfunction and temporary hypocalcaemia in up to 80% and 50%, respectively. Previous study from our institute showed a 3% rate of permanent vocal cord palsy and 16% of permanent hypoparathyroidism requiring calcium and/or vitamin D supplements. The use of dexamethasone has been studied in the past in total thyroidectomy patients and has been shown to be safe and effective in improving post-operative nausea and vomiting. No complications or drug related side effects were associated with a single dose of steroid. Recent studies have also shown that Dexamethasone is effective in improving voice outcome and hypocalcaemia in thyroidectomy patients. The investigators aim to study the effect of Dexamethasone in post-operative voice outcome and hypocalcaemia. Objective assessment of the vocal cords during phonation will be performed pre-operative and post-operatively. Serum Calcium level will be monitored.

This is a multi-specialty, double-blind, randomized, placebo-controlled trial involving the Departments of Surgery in United Christian Hospital, Tseung Kwan O Hospital and Department of Ear, Nose and Throat, United Christian Hospital and Tseung Kwan O Hospital, Kowloon East Cluster. The primary objective is to investigate the effect of Dexamethasone in post-operative voice outcome and hypocalcaemia in total thyroidectomy patients. The secondary outcome aims to investigate the mechanism of voice dysfunction in thyroidectomy patients using objective assessment tools.

To streamline the practice among various departments and to minimize any potential confounders, the peri-operative anaesthetic and post-operative analgesic protocols are standardized. The surgical techniques are also standardized using capsular dissection with positive identification and preservation of the recurrent laryngeal nerve.

Patient's voice and vocal cord mobility will be assessed pre-operatively and post-operatively. Objective assessment of the vocal cord will be carried out using video stroboscopy to document the mobility, waveform and vibration, symmetry and any arytenoid abnormality. Subjective and objective assessment of the voice outcome will be conducted by speech therapists using standardized voice assessment protocol. The trend of hypocalcaemia (Calcium level and parathyroid hormone level) will be monitored and correlated with the use of Dexamethasone. Possible side effect (e.g. wound infection) from the use of Dexamethasone will be analysed

Eligibility Criteria:
Inclusion Criteria:

* Aged 18 or above
* Patients undergoing total thyroidectomy for benign pathologies
* MNG
* Toxic nodular goitre
* Graves' disease

Exclusion Criteria:

* Non-communicable patients
* Patients contraindicated for steroid (DM, Hepatitis carrier, Tuberculosis, peptic ulcer disease)
* Patients contraindicated for analgesics including Panadol, Celebrex, Tramadol or Levobupivacaine
* Malignant thyroid disease
* Patients with previous thyroid surgery, or neck surgery
* Pre-existing hoarseness of voice of any cause or pre-existing vocal cord palsy
* Pregnancy / Lactating female patients
* Pre-existing renal disease / autoimmune disease on steroids
* Patients who require steroid cover during operation e.g. hydrocortisone perioperatively