[A case of unilateral and lesional mu rhythm--clinical and encephalographic development]

One case of a strictly unilateral left rolandic mu rhythm, revealing a metastatic tumor of the concerned region, is reported. The clinical feature consisted of partial Jacksonian motor seizures involving the upper limb and the face on the right side. As the tumoral process extended, the mu rhythm turned into a 6 c/sec theta rhythm, similarly located and reactive, then into a larger and more active slow focus. This focus transistorily decreased under X-ray treatment. The particular aspects of this observation are discussed in the light of the literature data.