Spasmus nutans as a presenting sign of an arachnoid cyst

Spasmus nutans, usually believed to be a benign entity, is a disorder of young children consisting of nystagmus, head nodding and an anomalous head position of unknown etiology. We present a patient with spasmus nutans who proved to have a large arachnoid cyst. When the cyst was shunted the nystagmus lessened. Recent studies suggest that the head nodding and anomalous head position are adaptive mechanisms that compensate for the nystagmus and not pathological in themselves. Therefore, spasmus nutans is not a triad of findings, but an acquired nystagmus with associated adaptive responses. Because spasmus nutans implies a benign entity composed of three requisite components, we feel it is an inaccurate term that should be abandoned. A better designation would be acquired nystagmus of infancy, which would not imply a benign etiology.