The remarkable illness, fatal familial insomnia, was initially described by Lugaresi and colleagues. This disorder, with onset in middle age and a clinical course of 7 to 36 months, is characterized by a progressive incapacity to sleep and to generate EEG sleep patterns. The cerebral changes consist mainly of profound neuronal loss in the anterior or anteroventral, and mediodorsal thalamic nuclei. These cases represent a usually familial form of prion disease similar to diseases that cause subacute spongiform encephalopathy (see Chap. 32). Interestingly, the alcoholic form of the Korsakoff amnesic state, associated with less severe lesions in the same thalamic nuclei, is also characterized by a sleep disturbance, taking the form of an increased frequency of intermittent periods of wakefulness (Martin et al). When carefully sought, similar sleep–wake disturbances have been found in sporadic Creutzfeldt-Jakob-prion disease (Landolt et al).
Major head injury is an important cause of sleep disturbance. The abnormalities, which may persist for months or years, consist mainly of a decrease in stages 1 and 2 sleep, and less than the expected amounts of REM sleep and dreaming. Some patients in the persistent vegetative state show a cycle of changes in the EEG, progressing from a picture of abortive spindles and K complexes with cyclic alterations in respiration and pupil size to the acquisition of a more normally structured sleep activity. This sequence usually presages the change from a state of coma to one of minimally conscious state (see Chap. 16). Organized sleep activity is absent in virtually all types of coma that are the result of anatomic damage to the brain. An exception, albeit a semantic one, occurs in the unusual condition known as “spindle coma,” in which persistent coma and the electrographic features of sleep coexist. This particular combination of events has been described after head trauma, and rarely, in association with profound metabolic encephalopathies. Despite what appears to be a genuine comatose state (not simply hypersomnolence) from a lesion of the reticular-activating system, the EEG displays frequent spindle activity and vertex waves, attesting to the integrity of thalamocortical pathways for sleep activity (see Nogueira de Melo et al). Also, in cases of traumatic bifrontal contusions, there may be a pathologic insomnia with mania that lasts days or weeks after the injury.
A variety of sleep disturbances may accompany brain tumors or follow surgical resection of an intracranial tumor. These include excessive daytime sleepiness, sleep apnea, and, rarely, nocturnal epilepsy. The location of the lesion, rather than the tumor type, is predictive of such a disturbance; thus, tumors affecting the hypothalamus, and pituitary are associated with excessive daytime drowsiness, whereas medullary lesions cause respiratory disturbances that may affect sleep (Rosen et al). A symptomatic form of narcolepsy is associated with tumors located adjacent to the third ventricle, and midbrain (see below). Schwartz and associates reported transient cataplexy (see further on) following surgery for a craniopharyngioma, but a delirious state has been more common in a few cases for which we have been consulted.