[Investigation of the clinical course and treatment of prion disease patients in the akinetic mutism state in Japan].

Twelve cases (one Gerstmann-Sträussler-Scheinker syndrome (P102L; definite), one genetic Creutzfeldt-Jakob disease (CJD) (V180I; definite) and ten sporadic CJD (7 MM1-type definite, 3 probable)), who reached the akinetic mutism state, were investigated with regard to their clinical course and treatment. They were hospitalized for a total of 3,968 days in the akinetic mutism state. In the nine definite cases, the median period from the akinetic mutism state to death was 22 months (average: 27.0 ± 23.3 months, range: 3-80 months) and median total disease duration was 27 months (average: 34.2 ± 30.1 months, range: 5-102 months). In the seven definite sporadic CJD cases, the median period from akinetic mutism to death was 21 months (average: 17.0 ± 9.6 months, range 3-28 months), and median total disease duration was 24 months (average: 20.6 ± 10.0 months, range: 5-31 months). Nasal-tube feeding was performed in all cases. Symptomatic treatments such as parenteral nutrition and antibiotic drugs were administered for complications such as respitory and urinary tract infections and digestive symptoms. Patients received rehabilitation and hot spring therapy regularly until death. Gastrostomy and/or tracheotomy was not performed in any case, the patients were not intubated nor was mechanical ventilation (including non-invasive positive pressure ventilation) applied. Vasoactive drugs were not administered. Clonazepam was administered for myoclonus in four patients but not in another three when myoclonus appeared. It is unclear whether the treatment influenced the duration of myoclonus. Our observations indicate that the extended survival period among Japanese prion disease patients is likely due to the management procedures implemented for prion disease in Japan, which are usually continued after the patients reach the akinetic mutism state. We speculate that nasal-tube feeding is the crucial factor that results in the prolonged disease duration of prion disease patients in the akinetic mutism state.