An E.e.g. Assessment of Encephalopathy in Parkinsonism.

In a review of the electroencephalographs (E.E.G.) in patients suffering from Parkinson's syndrome, England and his colleagues (England, Schwab, and Peterson, 1959) reported the association of E.E.G. slow wave abnormalities with those severe forms of the disease which showed, in addition to tremorrigidity symptoms, mental changes and akinesia. They defined akinesia as 'a reduction or loss of ability to initiate and maintain simple or complicated motor acts'. They found that patients thus severely affected were very sensitive to sedative drugs and they stated that patients with E.E.G. abnormalities and marked akinesia were bad candidates for neurolytic surgery. Hassler, Riechert, Mundinger, Umbach, and Ganglberger (1960) have reported that patients with a slow dominant frequency in their pre-operative E.E.G.s were more likely to show post-operative confusion, and the same workers stated that they considered that the E.E.G. slowing, which was produced by operation in a high proportion of their patients, did not depend on whether the stereotactic lesion was placed in the pallidum or in the ventral thalamus. There would therefore seem to be evidence to suggest that patients with 'encephalopathy' are liable to deteriorate post-operatively and that this postoperative deterioration, characterized by confusion and further slowing of the E.E.G., represents an increased encephalopathy. The advisedly non-specific term 'encephalopathy' has been used to refer to those disorders of brain function which, when severe, are manifested by confusion or alteration of consciousness and by a severe generalized electroencephalographic abnormality with a record dominated by large, slow waves (delta dominant). Work on hepatic encephalopathy (Laidlaw and Read, 1963, 1961) has shown that patients with lesser degrees of encephalopathy may not have objective neuropsychiatric signs but may show an abnormal E.E.G., namely, a reduction in frequency of the background activity,' a loss of