Prediction of prognosis in peripheral facial nerve paralysis using submandibular gland scintigraphy

In this study, we evaluated the ability of submandibular gland scintigraphy to predict the prognosis of peripheral facial nerve paralysis. Methods: Submandibular gland scintigraphy was performed in 78 patients with acute peripheral facial nerve paralysis. After injection of 180-370 MBq [Tc-99m]pertechnetate, serial I-min images were acquired for 25 min. At 15 min after injection of radionuclide, ascorbic acid was administered intraorally to stimulate salivary secretion. Regions of interest were set manually on both submandibular glands, and time-activity curves were generated. The ratios of peak count density (PCR) and washout (WR) of the affected side to the normal side were calculated. Parameters of greater than or equal to 0.8 suggested normal affected submandibular function and indicated a good prognosis. Results: Complete recovery of facial nerve paralysis was observed in 52 of 78 patients. The sensitivity, specificity and accuracy of PCR for a good prognosis were 79%, 50% and 69%, and those of WR were 85%, 77% and 82%, respectively. Positive and negative predictive values for a good prognosis were 76% and 54% in PCR and 88% and 71% in WR, respectively. When WR obtained within 14 days of the onset was used, positive and negative predictive values for a good prognosis were 94% and 73%, respectively. None of the eight patients who had values of <0.8 for both parameters within 14 days of the onset recovered completely. Conclusion: Submandibular gland scintigraphy can serve as a reliable indicator to predict the prognosis of acute peripheral facial nerve paralysis in its early symptomatic period.