Case 2: The 10-month-old right-hander

Abstract

A 10-month-old boy presented with a right hand preference. He was born (of nonconsanguineous parents) at term following an unremarkable pregnancy and delivery with normal Apgar scores and a birth weight of 4250 g. His family history was noncontributory. Parents first noted left-sided fisting and an inability to use the left hand at approximately four months of age. He would not grasp objects in this hand even when presented directly. He had a weak left leg. The parents did note some improvement over time. He had rolled over front to back at six months of age and had sat unassisted by seven months of age. He was unable to sit up from a lying position and did not stand. Language and social development was age-appropriate. No seizures, loss of consciousness or any abnormal movements had been observed. Physical examination revealed a well-nourished infant in no distress. His head circumference was 46.5 cm (50% to 75%). His general examination including the skin revealed no abnormalities. The neurological examination revealed an alert infant who babbled. He had symmetrical and reactive pupils. His cranial nerves were preserved. The left thumb appeared to be smaller than the right thumb. The rest of his muscular mass and tone seemed normal. The left arm and especially the left hand were kept preferentially in a flexed position; tone was not significantly increased on the left side. There was left-handed fisting. The hand could be opened passively. He sat unassisted. There was an obvious weakness of the left side with a greater weakness in the upper extremity. When placed in a standing position, he placed more weight on his right leg. When placed ventrally, he kept his left arm next to his body and did not attempt to crawl. He was hyper-reflexive on the left side with a slight predominance in the arm and a positive Babinski sign. An imaging study revealed the diagnosis.