Thyrotoxic periodic paralysis: sonographic appearances of the thyroid.

PURPOSE: The aim of the study was to describe the sonographic appearances of the thyroid in patients with thyrotoxic periodic paralysis (TPP).

METHODS

Of the 25 patients diagnosed with TPP between January 1, 1998, and December 31, 2001, as identified by a search of our patient database, 13 had undergone sonography of the thyroid. We retrospectively reviewed the clinical records and thyroid sonograms of these 13 patients. The sonograms were assessed subjectively for thyroid size, echogenicity, vascularity, and the presence of solid nodules and cysts.

RESULTS

Sonography showed abnormality of the thyroid in all 13 patients. In 11 patients (85%), sonography showed widespread hypoechogenicity (compared with the muscle) whose distribution was diffuse (6 patients) or patchy (5 patients) and diffusely distributed areas of hypervascularity (type 1 pattern). All 11 of these patients had a clinical diagnosis of Graves' disease. One patient (8%) had multinodular goiter and enlargement of the thyroid with multiple heterogeneous solid nodules and cysts (type 2 pattern); the clinical diagnosis was toxic multinodal goiter. One patient (8%) had a combination of type 1 and type 2 patterns and a clinical diagnosis of Graves' disease.

CONCLUSIONS

The sonographic abnormalities of the thyroid in patients with TPP reflect the common underlying causes of thyrotoxicosis in the general population. The sonographic appearances associated with Graves' disease (type 1 pattern) were the most common abnormality detected. No sonographic features specific to TPP were identified.