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Implantation of embryonic brain tissue into the putamens of parkinsonism patients produces relative improvement of symptomatic hypokinesia (less worsening compared with unoperated controls).¹ This is no surprise; that symptoms of parkinsonism are improved by deep cerebral lesions was first described by Parkinson when 1 of his 1817 patients was afflicted with a hemispheral stroke. The immediate therapeutic efficacy of various brain lesions has been known for almost a century.² Targeted electrical inactivation or destruction is now a widely accepted therapeutic procedure, focused recently upon the subthalamic nucleus. Monkeys with substantia nigra lesions produced by methylphenyltetrahydropyridine infusion are superior models of human parkinsonism. It is unlikely that the immediate and early improvement following embryonal midbrain implantation in these preparations can be explained by integrative physiological graft to host connections. Other tissue implantations produced similar effects, as did adrenal gland implants in patients.^2-4

The simplest inference from these facts (Occam’s razor) is . . . [Full Text of this Article]

AUTHOR INFORMATION

William M. Landau, MD