原発性橋出血にみられた幻覚症状—5自験例における検討

VISUAL HALLUCINATIONS ASSOCIATED WITH PRIMARY PONTILE HEMORRHAGES

Ⅰ．はじめに

　従来，橋出血は脳卒中のうちでも，最も重症とされ，その報告の多くは死亡例であつた^1,2）。しかし近時脳卒中への関心が高まるとともに，診断技術の向上，特にCTスキャンの登場により，橋に限局した出血例の報告が見られるようになつた^3,4）。軽症例とも言えるこれら橋出血は，神経学的にも多彩な症状を呈し，興味深い。この症状の分析に関しては一部はすでに報告した^5）。今回はそれらの諸症状のうち，幻覚を中心とする精神症状につき報告する。

The present paper describes five cases of visual hallucinations associated with primary pontile hemorrhage. Three patients were males, two were females, with a mean age of 54 years (age range 48 to 65 years). All patients were admitted to our hospital within 48 hours after the sudden onset of symptoms.

A clinical diagnosis of pontile hemorrhage was made in four cases based on characteristic neuro-logical symptoms such as cranial nerve involve-ment, alternative hemiplegia, etc. One case was misdiagnosed as thalamic hemorrhage based on symptoms such as headache, vertigo, slight hemi-paresis and hemisensory deficit. The correct diagnosis of pontile hemorrhage was established in this patient and confirmed in three of the others by means of CT-scanning. In one patient, studied before CT-scanning became available, the clinical diagnosis of pontile hemorrhage was confirmed by vertebral angiography and pneumoencephalotomo-graphy.

On admission, the patients were somnolent. As their neurological symptoms improved, and they became more alert, visual hallucinations occurred in all cases. These hallucinations began between 8 and 18 days after the onset of neurological symptoms, and lasted for 2 to 14 days. The patients described their hallucinations as colorful and vivid, e. g. "a green horsecarriage " (Case 1), "a blackand white serpent creeping on the wall of a building near the hospital" (Case 2), "a red kettle and a white bucket hanging from the ceiling" (Case 3), "a stove in which firewood was burning" (Case 4), "fish swimming in the room, and a scene from my countryside" (Case 5). The patients were generally aware of the delusive nature of their visions, and only one patient transiently believed them to be real. All patients showed good neuro-logical recovery within 3 months.

The first case of organic hallucinations caused by a brainstem lesion was published in 1922 by Jean Lhermitte, who introduced the concept of "peduncular hallucination". Since then, many similar cases have been published. The present paper, however, is the first to report on organic hallucinations caused by localized pontile hemor-rhage.

The mechanism of these hallucinations is un-certain, but the present authors suggest that an important factor may be damage to the ascending reticular activating system. This would cause "dissolution of the nervous system"in the sense of Hughlings Jackson, including e. g. disruption of the normal sleep-wakefulness rhythm. Jackson suggested that dissolution of the nervous system might produce mental symptoms such as halluci-nations, this concept of mental illness has been renewed by Henri Ey, who grades acute psychosis on a scale of increasing disorganization of conscious-ness when hallucination states have an intermediate position.