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Visual Hallucinations in Mild Dementia  - A Rare Occurrence of Lhermitte's Hallucinosis  [February 5, 1999] - Raphael J. Leo, M.D., and Kristin Stievater Ahrens, M.D. EXCERT

The elderly patient, presenting with new-onset visual hallucinations,confronts the consultation-liaison psychiatrist with an array of diagnostic possibilities. A number of psychiatric disorders,along with organic etiologies, must be entertained in the differential diagnosis. We report on a patient with visual hallucinations who was found to have mild cognitive deficits. She did not, however, demonstrate other symptoms or signs suggesting common organic or functional psychiatric disorders

One syndrome appeared to most aptly apply, based upon clinical and laboratory investigations, that is, Lhermitte's hallucinosis. Originally described in 1922, Lhermitte reported a case of a person experiencing hallucinations of strange animals and costumed humans and children, stemming from lesions affecting the mid-brain and pons

Case Report

A 67-year-old, married, white woman, who was mother of seven, …presented for evaluation of depression. She reported experiencing depression for "years," that is, feeling "mostly sad,"…... There was no recent or prior history of manic episodes or delusions. She denied any alcohol or illicit substance use.

The patient complained of "creatures" that come "out of the air," move about her house, and "travel right through the walls without leaving a hole or a mark." The patient described these creatures as about 1-foot in height; they have a head and "face colored as if with charcoal or Halloween makeup." Their bodies were covered with scarves, gowns, or rags. The patient was rather jocular and giddy at times, often making light of such visual phenomena and referring to them as "imitation kids." The patient complained of being bothered by seeing such "children" in her house, viewing them as some sort of "phantom family."  While she appeared to talk about them as if convinced that such images were "real," periodically she would question whether these were the "product of her mind."

On examination the patient was alert, without fluctuation of consciousness. She was attentive, aware of her surroundings. Her speech was rapid but clear and coherent (as per her husband, this was typical for the patient). ………

Her husband reported that, following a severe headache, the patient's hallucinations began about 2 months before psychiatric evaluation. He reported that she had episodes of double vision and "confused behavior," for example, difficulty turning the correct burners on the stove or taking the wrong direction in their home. Interview with the husband about her activities of daily living and personality yielded a Blessed Dementia Rating Scale of 4, with predominance of difficulties in performance of everyday activities. The patient was not incontinent and did not have difficulties with dressing, eating, or significant personality changes.

The patient was diagnosed as having a mild dementia, with deficits in memory for recent events, visual spatial judgment, constructional praxis, abstract problem-solving ability with normal orientation, normal new learning and recall, verbal intellect, and language functioning. The diagnosis of Lhermitte's hallucinosis was based upon clinical and radiographic findings.

…………….Infarcts in the region of the midbrain or brainstem have been associated with well-formed images of animals, people, and lilliputian images, much as were reported by our case. Such well-formed hallucinations, in conjunction with brainstem or midbrain lesions,have been referred to as Lhermitte's (or peduncular) hallucinosis.Such hallucinations occur in the context of dementia that is mild in severity. Rather than being distressed about such hallucinations, often such hallucinations are recognized as unreal or result in a silly, inappropriate affect, as was noted in this case…………

A trial of risperidone was begun but was inefficacious in reducing the visual hallucinations.

 References Lhermitte J: Syndrome de la calotte du pedoncule cerebral. Les troubles psycho-sensoriels dans les lesions du mesocephale. Rev Neurol (Paris) 1922; 38:1359–1365