hyperammimia (accumulated because of low ammoinia to urea metabolism by liver) causes interruption of the posture pathway in the rostral reticular formation and abnormal joint proprioception. The lapse of posture has been termed “negative clonus” because during tonic muscle contraction (i.e. posture) a short EMG silent period precedes the tremor.3 In essence, the patient struggles to maintain posture while posture control repetitively vanishes.