LAUSR

A -year-old woman complained of limb weakness and walking instability for 12 years. She presented with difficulty in running compared to her peers since she was young. At the age of 10 years, she presented with stiffness in both lower limbs and walking instability, especially when climbing stairs. At the same time, she exhibited muscle atrophy in the left hand and hand tremors. At the age of 16 years, she had trouble writing with her right hand. One year later, she presented with slurred speech, which gradually worsened. However, she did not show any apparent dysphagia. She was from a non-consanguineous family, and had one brother and two sisters. One of her older sisters also exhibited similar symptoms. The patient had normal cognitive function. She presented with slow saccades and horizontal nystagmus. The following were also observed: tongue atrophy with fasciculation (Fig. 1a), dysarthria, and muscle atrophy in thenar, hypothenar, and interosseous muscles of both hands, which presented as claw hands. Contracture of the Achilles tendon and significant spastic muscular hypertonia of both lower extremities were seen. Muscle strength examination revealed that the flexor neck muscles were graded 5, the proximal muscles of the extremities were graded 4, and the distal upper/lower extremity muscles were graded 2, according to the Medical Research Council scale. Brisk tendon reflexes, positive Babinski’s sign, and Hoffmann’s sign were also revealed. She exhibited dysmetria upon performing the finger-to-nose test. Questions