Electroencephalographic criteria of epileptic syndrome in patients with parkinsonism
Tatiana Elistratova, M.D., Ph.D. and Andrey Soloviev, M.D., Ph.D.
In spite of pathogenetic similarity of Parkinson’s disease (PD) and idiopathic epilepsy, they are usually considered as antagonistic diseases. It is known that in PD patients, epilepsy occurs three times less often than in the rest of the population, and the development of PD in patients with epilepsy results in less frequent occurrence or disappearance of epileptic attacks. However, one should distinguish between epileptic syndrome (ES) in chronic alcoholic intoxication (CAI) and idiopathic epilepsy.
ES is a result of toxic and metabolic encephalopathy, does not require special treatment with antiepileptic preparations, and does not develop if the patient stops using alcohol. At the same time, there are no clear data about a relation between CAI and PD (or Parkinson’s syndromes (PS)). ES of alcoholic genesis (ESAG) also occurs among patients suffering from CAI and PD (PS). Implementation of a comparative analysis of electroencephalograms (EEG) of patients with ESAG, patients with ESAG and PD (PS) can be used as an additional criterion of differentiated diagnosis.
With the goal of studying EEG features in patients with PD and PS with ESAG, we have analyzed EEG of 154 patients older than 45 years. Thirty-three of them had ESAG without PD (PS), 7 had ESAG in combination with PD (PS), 15 had PD, 25 had PS of vascular or toxic genesis, 17 had idiopathic epilepsy, 19 had symptomatic epilepsy, 38 patients did not have ES and PD (PS), but they suffered from discirculatory encephalopathy (DE) I-II stages (in fact, they were patients with age-related brain changes).
The EEG of all patients with ESAG irrespective of PD (PS) comorbidity, as well as the overwhelming majority of the EEG (92.5%) of the patients with PD (PS) not suffering from ES, in addition to a change of amplitude–frequency indices in the direction of slowing down, applanation and irregularity of the basic rhythm, diffusive appearance of excess quantity of slow waves, were described by rarely occurred paroxysmal activity, absence of epileptic activity, low reaction of activation after hyperventilation, photo- and phonostimulation, «muscular tremor» and artifacts which did not occur in the patients with idiopathic and symptomatic epilepsy and were not typical for the patients with DE. At the same time in 44.4% of cases, the EEG of the patients with idiopathic and symptomatic epilepsy was notable for focal slow-wave activity in the affected hemisphere, in 22.2% – for epileptic activity; in 19.4% – for a high “paroxysmal readiness” of the brain, in 14.0% – for the low-amplitude type and slight diffuse changes. In 39.5%, the EEG of the patients without ES, CAI and PD (PS) has shown a dysfunction of the median-truncal structures; in 5.3%, a high “paroxysmal readiness” of the brain has been detected, in 5.3% – focal low-wave activity, in 26.3 %, the low-amplitude type mild diffuse changes have been registered, and in 23.6%, pathological changes have not been detected.
Thus, the occurrence of the above-mentioned features of the EEG can be used as an additional criterion of differential diagnosis of ES in patients with PD (PS).