Peduncular hallucinosis: unusual complication of cardiac catheterization.

Abstract: Peduncular hallucinosis (PH) is a rare form of visual hallucination characterized by vivid, nonstereotypical visual images of people, animals, and plants of brief duration that are nonthreatening to the patient. The clinical syndrome of PH consists of formed visual hallucinations, localizing signs of the offending lesion, and sleep disturbances. In the absence of localizing focal neurologic deficits, it is easily confused with a delirium or psychosis. It is seen with lesions involving the upper brainstem and diencephalon. The authors report a case of PH due to ischemic infarction of the midbrain after cardiac catheterization. Although PH has been reported after vertebral angiography, it has never been reported as a complication of cardiac catheterization.

Key Words: brainstem infarction, cardiac catheterization, peduncular hallucinations

**********

Peduncular hallucinosis (PH), a special form of visual hallucination, is characterized by vivid, nonstereotypical-colored visual images of people, animals, plants, and scenes of brief duration that are nonthreatening to the patient. (1,2) Peduncular hallucinations have been reported in vascular and infective lesions of the thalamus, pars reticulata of the substantia nigra, midbrain, pons, and basal diencephalon, as well as compression of the midbrain. (3) We report a case of PH that occurred after cardiac catheterization. To the best of our knowledge, no such case has been previously reported.

Case Report

An 84-year-old man with a medical history of coronary artery disease, coronary artery bypass grafting, hypertension, and hyperlipidemia was hospitalized for an elective cardiac catheterization following a positive stress test. At cardiac catheterization, he was found to have significant stenosis of the left anterior descending artery distal to the internal mammary graft. This was treated with angioplasty and stenting. The patient had received hydromorphone and midazolam before and during the procedure. Twelve hours postprocedure, the patient complained of headache. He was found trying to reach for things in the air and talking to inanimate objects. He was having visual hallucinations involving people and was talking to them. He preferred to have his eyes closed and seemed to be enjoying these hallucinations. He was able to answer questions appropriately and was obeying simple commands. Neurologic examination did not reveal any focal deficits. Initial computed tomographic scan of the brain showed mild diffuse atrophy with no focal abnormality. All basic laboratory tests (complete blood count, electrolytes, creatinine) were normal. Electroencephalography did not show any epileptiform discharges. Initially, these hallucinations and intermittent agitation were thought to be secondary to premedications received for cardiac catheterization. However, the symptoms persisted and he was noted to have altered sleep pattern with daytime somnolence. Repeat computed tomographic scan of the brain 2 days later revealed a lacunar infarct involving the midbrain (Fig. 1). These hallucinations persisted for 8 days and then resolved.

Discussion

The clinical syndrome of PH consists of formed, vivid, highly colored visual hallucinations and is composed of formed and often animate objects. These visual hallucinations may be of two types. In the first type, the hallucinations are often detached from the patient's own thought and actions, and are not mistaken for reality. In the second type, the hallucinations are mistaken for reality and are associated with agitation and delusion. (2,3) These hallucinations are not frightening or stereotypical, and are often associated with nocturnal wakefulness and daytime somnolence. These tend to occur in the evening and usually persist for several days.

[ILLUSTRATION OMITTED]

Lhermitte (1) first described PH in 1922 in a 72-year-old woman who had vivid, colorful visual hallucinations involving people and animals. A few years later, Van Bogaert (2) described a similar case, coined the term "peduncular hallucinations," and provided pathologic evidence of brainstem infarction. The localizing value of visual hallucinations is still unclear. A number of explanations have been proposed for the origin of visual hallucinations in vascular lesions that are so distant from the visual system. Cogan divided visual hallucinations into two types--irritative and release. (4) In the irritative type, stereotypical paroxysmal disturbances in the cortical function occur with other motor and sensory dysfunction. When the irritative focus is occipital, patients describe brief stereotypical flashes of light or color. When the focus is in the temporal lobe, complex stereotypical formed images are reported. The release type of visual hallucinosis is characterized by more continuous visual images that change from one episode to the next but are not associated with any other motor or sensory dysfunction. These hallucinations are attributed to a loss of normal visual input occurring as a consequence of a lesion anywhere in the visual system or as a result of sensory deprivation. Generally, release hallucinations are of less localizing value except for PH, which is associated with other signs of midbrain dysfunction. (5) Because sleep disturbances are almost invariably associated with PH, damage to the ascending reticular activating system has also been suggested. (1,5) Our patient had nonthreatening, vivid visual hallucinations with sleep disturbance consistent with PH. This was secondary to brainstem infarct.

Stroke is one of the recognized complications of angiographic procedures and is a rare but potentially devastating complication of cardiac catheterization. The incidence of stroke was found to be 0.07% in the second registry of the Society for Cardiac Angiography. (6) This complication is thought to be caused by disruption of atheromatous plaques on the walls of the aorta.

Conclusion

PH has been reported in various vascular and infective lesions of the thalamus, the pars reticulata of substantia nigra, midbrain, pons, and basal diencephalon, as well as compression of the midbrain. (3) PH after vertebral angiography has been reported once in the literature. (6) However, PH has never been reported as a complication of cardiac catheterization before. The clinical manifestations of PH are probably often mistaken for postoperative altered sensorium or psychosis and are not investigated any further. (3) Although formed visual hallucinations do not generally have a strong localizing value, any subtle sign of brainstem disorder should be carefully sought in patients with acute visual hallucinations.

Accepted November 5, 2003.

References

1. Lhermitte J. Syndrome de la calotte du pedoncule cerebral: les troubles psycho-sensoriles dans les lesions du mesencephale. Rev Neurol 1922;38:1359-1363.

2. Van Bogaert L. L'Hallucinose pedonculaire. Rev Neurol 1927;40:608-617.

3. Kumar R, Behari S, Wahi J, et al. Peduncular hallucinosis: an unusual sequel to surgical intervention in the suprasellar region. Br J Neurosurg 1999;13:500-503.

4. Cogan DG. Visual hallucinations as release phenomena. Albrecht Von Graefes Arch Klin Exp Ophthalmol 1973;188:139-150.

5. Geller TJ, Bellur SN. Peduncular hallucinosis: magnetic resonance imaging confirmation of mesencephalic infarction during life. Ann Neurol 1987;21:602-604.

6. Johnson LW, Lozner EC, Johnson S, et al. Coronary arteriography 1984-1987: a report of the Registry of the Society for Cardiac Angiography and Interventions. I. Results and complications. Cathet Cardiovasc Diagn 1989;17:5-10.

RELATED ARTICLE: Key Points

* Peduncular hallucinosis is a rare form of visual hallucination.

* Peduncular hallucinosis is seen with lesions involving the upper brainstem and diencephalon.

* Peduncular hallucinosis is easily confused with a delirium or psychosis.

Desikan Kamalakannan, MD, MRCP, Srihari Ravi, MD, and Shyam S. Moudgil, MD

From the Department of Internal Medicine, St. John Hospital and Medical Center, Detroit, MI.

Reprint requests to Desikan Kamalakannan, MD, MRCP, Department of Internal Medicine, St. John Hospital and Medical Center, 22201, Moross Road, Professional Building 2, Suite 80, Detroit, MI 48236. Email: [e-mail]