Electroencephalographic changes in neurosyphilis

Abstract

A study is reported of EEG findings in neurosyphilis based on 241 electroencephalograms obtained from 110 patients in the following clinical categories: 35 with dementia paralytica, 24 with taboparalysis, 19 with tabes dorsalis, and 32 with other varieties of neurosyphilis. After describing the criteria of abnormal tracings the EEGs of 110 patients are divided into 38 normal and 13 border-line; there are 23 cases of slight, 30 of moderate, and 6 of severe abnormality. Among the 59 abnormal EEGs, 53 showed marked constancy, characterized by a dominant frequency at the lower limit of normal, trains of 5–7 c/sec. activity of low amplitude, shifts in frequency, and numerous abnormal single potentials. The changes are diffuse, being most marked in the parietal and frontal leads, and are practically unaffected by hyperpnoea. A clear difference is found between the incidence of abnormality in the mainly spinal as compared with the mainly cerebral varieties, and this applies also the gravity of the electroencephalographic changes. Thus, moderate to severe abnormality occurred in only 9 per cent of the patients with tabes dorsalis, but in 52 per cent of thise with dementia paralytica. The incidence of abnormality is found to be much higher among the young than in the old age group, being 81 per cent in those under 40 as compared with 42 per cent in those over 60 yeats of age. This difference is real and is not a function of duration of the neurosyphilitic symptoms, type of lesion or type of treatment. In the presence of severe mental symptoms, especially euphoria and dementia, the incidence of abnormalities is high (79 per cent) whereas it is low in “non-organic” psychoses (43 per cent) and 38 per cent in the presence of only neurasthenic symptoms. EEG abnormality is not correlated with abnormal spinal fluid findings, although there is a somewhat higher incidence of EEG abnormality when spinal fluid and blood Wassermann reactions are positive. When the pneumoencephalograms are normal, the incidence of moderate and severe abnormality was only 11 per cent as compared with almost 70 per cent in the presence of ventricular or cortical atrophy. A study of 41 patients who had received fever therapy within 1–2 weeks showed less effect on the EEG than on the clinical condition. There was a tendancy, however, for the EEG to improve in a higher percentage of patients who were improved clinically, than in those whose clinical condition remained stationary after treatment.