RESUMO
We describe a patient with hypothyroidism displaying "dropped head" syndrome. A 50-year-old man visited our clinic because he was unable to hold his head in the natural position. He had weakness and hypertrophy of the neck extensor muscles. Tendon reflexes were diminished or absent in all limbs. Mounding phenomena were observed in the bilateral upper extremities. Blood biochemical analysis revealed hypothyroidism, hyperlipidemia, and elevated levels of muscle-derived enzymes. Magnetic resonance imaging (MRI) of the neck demonstrated swelling and hyperintensity of the neck extensor muscles on T2-weighted images. The result of biopsy of the right biceps brachii muscle suggested mild atrophy of type 2 fibers. The diameters of the muscle fibers exhibited mild variation. No inflammatory changes were observed. We diagnosed hin as having "dropped head" syndrome due to hypothyroidism. Administration of thyroid hormone agent gradually improved his condition, and he became able to hold his head in the natural position. Levels of muscle-derived enzymes normalized and his hyperlipidemia remitted. Neck MRI also revealed improvement. Our findings suggest that hypothyroidism should be considered in the differential diagnosis of "dropped head" syndrome, although only a few cases like ours have been reported.