This was a prospective case-control study. From July 2017 to Dec. 2018, investigators recruited 38 patients, who had undergone a successful operation of total parathyroidectomy and bilateral thymectomy (TPxBT) plus autotransplantation for symptomatic secondary hyperparathyroidism as the study group. In the same period 4 patients who had a surgical failure were excluded from the study. Indications for surgery were patients who had undergone long-term regular hemodialysis or continuous ambulatory peritoneal dialysis (CAPD), with serum levels of Ca \> 10.1 mg/dL, P \> 5.5 mg/dL, alkaline phosphatase (Alk-ptase) \> 94 U/L and intact parathyroid hormone(iPTH) \> 800 pg/mL and with symptoms and signs such as skin itching, bone pain, general weakness, insomnia and T-score of bone mineral density (BMD) (the lowest T-score of lumbar spine 1-4, global femur, femoral neck, radial 1/3, and global radius) \< -2.5. During surgery, Total parathyroidectomy and bilateral thymectomy was performed plus autotranplantation of 100 mg of hyperplastic parathyroid tissue to the subcutaneous tissue of the forearm without harboring an arteriovenous fistula.
Ten patients with regular hemodialysis who had developed mild secondary hyperparathyroidism (iPTH around 500 pg/mL) but did not undergo parathyroidectomy were recruited as the control group.
Investigators recorded patients' age, symptoms, gender, body mass index (BMI) and measured serum levels of Ca, P, Alk-ptase and iPTH, and BMD (T-score). The Investigators also recorded patients' voice quality, airway invasion during swallowing and pulmonary functions before surgery and 4 months after surgery to find the changes after surgery. In the control group, investigators recorded and measured these items at baseline and 4 months later.
At 1 week after surgery, serum Ca, P, Alk-ptase and iPTH levels were measured again to make sure that the operation was successful. A successful operation was defined as iPTH levels \< 72 pg/mL within 1 week after surgery. Four patients were excluded from this study with a surgical failure in the same period.
The perceptual evaluation of voice quality such as speech impairment and speech quality by means of multidimensional clinical measurements based on auditory methods with grade, hoarseness, roughness, breathiness, asthenia, and strain (GRBAS) on a scale (0-3) (normal-high degree) were performed by the ear, nose, and throat specialist (Dr. Lai, C.C.). Voice handicap index (VHI-10) (\>11, abnormal) and eating assessment tool (EAT-10) (≥ 3, abnormal) were evaluated by patients themselves.
Acoustic and aerodynamic measurements were applied to recordings of each subject producing sustained vowel productions in a soundproof room. Acoustic variables including jitter (Jitt), shimmer (ShdB), noise-to-harmonic ratio (NHR), fundamental frequency (Fo), and high pitch were measured using computerized speech laboratory (Core Model SCL # 4300B, KayPENTAX Elementries, Lincoln park, NJ).
The maximal phonation time and s/z ratio were measured with circumferentially vented pneumotachography mask and differential transducers of the Aerophone system (Aerophone II, Model 6800, KayPENTAX Elementrics). Vocal cord mobility, vocal cord closure (complete or incomplete), airway invasion during swallowing were inspected with fiber-optic endoscopy to show premature spillage, penetration-aspiration scale levels (1-8) (no entry of material into the larynx or trachea-material enter the airway passes below vocal folds and no effort is made to eject) (\>1, abnormal). The Yale pharyngeal residue severity rating scale for vallecula (0-4) (non-trace-mild-moderate-severe) and pyriform sinus (0-4) were also performed by the ENT specialist.
The specialist of chest medicine (Dr. Chang, H.C.) performed pulmonary function tests including forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), bronchodilator test (BDT) (a positive response to BDT defined by the American Thoracic Society as an increase in FEV1 or FVC ≥ 12% and 200 ml), total lung capacity (TLC), and alveolar volume (VA) using MasterScope (Jaeger, VIASYS healthcare GmbH, Höchberg, Germany), and diffusion capacity of the lung for carbon monoxide (DLCO) using Vmax Autobox (SensorMedics, a subsidiary of VIASYS healthcare, California, USA). The 6 minutes walking test (6MWT) was also performed to evaluate distance (meter) and O2 desaturation (differences of O2 saturation between pre- and post-tests) (defined as positive if O2 desaturation ≧ 4%).
