Atypical dementia and spastic paraplegia in a patient with primary lateral sclerosis and numerous necortical beta amyloid plaques: new disorder or Alzheimer's disease variant?

Abstract

Primary lateral sclerosis (PLS) and hereditary spastic paraplegia (HSP) are clinically similar disorders in which progressive lower limb spasticity and corticospinal tract degeneration are characteristic. We report the occurrence of progressive spastic paraplegia and frontal systems dementia in a patient with postmortem features of PLS combined with moderate Alzheimer-like changes in neocortex and hippocampus. This combination of clinical and neuropathologic findings has not been described in PLS or HSP and varies from other cases in which spastic paraplegia, dementia, and Alzheimer neuropathology occurred concurrently. This 69-year-old woman developed spastic quadriplegia and dementia over 12 years. Left leg weakness progressed over 7 years to paraplegia, then quadriplegia by age 68. Sensory and cerebellar function were preserved and fasciculations were absent. Dementia characterized by concrete thinking, perseveration, and impaired executive function appeared in the seventh year and remained relatively stable until 6 months before death at age 69. Degeneration of the lateral corticospinal and dorsal spinocerebellar tracts confined to the spinal cord was evident at postmortem examination. Brain stem, midbrain, and cerebellum were normal. Numerous beta/A4 amyloid positive diffuse plaques (10-15/200x field) were apparent in neocortex, and neurofibrillary tangles immunopositive for paired helical filament were detected in hippocampus. This case broadens the spectrum of disorders associated with Alzheimer neuropathologic changes. The relationship between PLS, HSP, and Alzheimer's disease requires further study.