Too often, parkinsonism is seen as no more than a movement disorder, but it may also involve a number of other aspects, including sleep disturbances of various sorts. People with Parkinson’s may sleep poorly at night and often have chronic sleep deprivation. Their sleep may be marked by vivid and sometimes bizarre dreams, or nightmares in which they are awake but paralyzed, helpless to combat dream images being superimposed on their waking consciousness. All of these factors additionally predispose to hallucination.
In 1922 the French neurologist Jean Lhermitte described the sudden onset of visual hallucinations in an elderly patient—people in costume, children playing, animals around her (she would sometimes try to touch them). The patient had insomnia at night and drowsiness in the daytime, and her hallucinations tended to come at dusk.
Though this lady had dramatic visual hallucinations, she had no visual impairments and no lesions in the visual cortex. But she had neurological signs suggesting an unusual pattern of damage in parts of the brain stem, the midbrain, and the pons. It was well known at this point that lesions in the visual pathway could cause hallucinations, but it was not clear how damage in the midbrain—not a visual area—could do so. Lhermitte thought such hallucinations might go with a derangement of the sleep-wake cycle, that they were essentially dreams or dream fragments invading daytime consciousness.
Five years later, the Belgian neurologist Ludo van Bogaert reported a somewhat similar case—his patient suddenly started seeing the heads of animals projected on the walls of his house at dusk. There were neurological signs similar to those of Lhermitte’s patient, and van Bogaert also surmised midbrain damage. When his patient died, a year later, an autopsy revealed a large midbrain infarction involving (among other structures) the cerebral peduncles (hence his coinage of the term “peduncular hallucinations”).
In Parkinson’s disease, postencephalitic parkinsonism, and Lewy body disease, there is damage to the brain stem and associated structures, as there is in peduncular hallucinosis—though the damage occurs gradually and not abruptly, as with a stroke. In all of these degenerative diseases, however, there may be hallucinations, as well as sleep, movement, and cognitive disorders. But the hallucinations are markedly different from those of CBS; they are nearly always complex rather than elementary, often multisensory, and more apt to lead to delusions, which CBS alone rarely does. The hallucinations of brain-stem origin seem to be associated with abnormalities in the acetylcholine transmitter system—abnormalities that may be aggravated by giving the patient L-dopa or similar drugs, which heighten the dopamine load on an already fragile and stressed cholinergic system.
People with ordinary Parkinson’s disease may be active and retain their intellectual powers for decades—Thomas
Hobbes, the philosopher, for instance, developed “the shaking palsy” around the age of fifty, when he was completing his
Edna B. seems to have this disease, though the diagnosis of Lewy body disease cannot be made with certainty in life without doing a brain biopsy. Mrs. B. enjoyed excellent health until her mid-sixties, but in 2009 she developed some tremor in the hands, her first symptoms of parkinsonism. By the summer of 2010 her symptoms included some slowing of movement and speech as well as problems with memory and concentration—she would forget words and thoughts, lose the thread of what she was saying and thinking, and, most distressingly of all, she had hallucinations.
