Peduncular hallucinosis
Encyclopedia
Peduncular hallucinosis, also known as Lhermitte's peduncular hallucinosis, is a rare neurological syndrome with a relatively rich series of detailed clinical case studies in the medical literature.
The French neurologist Jean Lhermitte
in 1922 first wrote about a patient with odd visual hallucinations that were associated with suggestions of brain damage involving the midbrain and the pons
. After other case studies were published, this type of presentation was labelled "peduncular hallucinosis."
The accumulation of additional cases by Lhermitte and by others influenced academic medical debate about hallucinations and about behavioral neurology
.
Lhermitte provided a full account of his work in this area in his book "Les hallucinations: clinique et physiopathologie" published in Paris in 1951 by Doin publishing.
Contemporary researchers, with access to new technologies in medical brain imagery, have confirmed the brain localization of these unusual hallucinations.
which described a 72-year-old woman’s visual hallucinations of colorfully dressed people and children which occurred at dusk. The hallucinations occurred during normal conscious state and the patient’s neurological signs were associated with those characteristic of an infarct to the midbrain and pons
. Von Bogaert, Lhermitte’s colleague, named these type of hallucinations “peduncular” in reference to the cerebral peduncles as well as to the midbrain and its surroundings. In 1925, Von Bogaert was the first person to describe the pathology of peduncular hallucinosis though an autopsy of a patient. His autopsy revealed the infarction of many areas of the brain including the inferolateral red nucleus, superior colliculus
, periaqueductal gray
, third nerve nucleus, superior cerebellar peduncle, substantia nigra
, and pulvinar
. Later in 1932, Lhermitte, Levy, and Trelles discovered an association between peduncular hallucinosis and “pigmentary degeneration of the periaqueductal gray and the degeneration of the occulomotor nucleus.” Posterior thalamic lesions were also found to be linked to peduncular hallucinosis by De Morsier. More recently, magnetic resonance imaging
(MRI) has been used to localize lesions in the brain characteristic of peduncular hallucinosis. In 1987, the first case of peduncular hallucinosis was reported in which MRI was used to locate a midbrain lesion.
, and following regional surgical or angiographic interventions. These pathologies are mainly near the base of the brain and the hallucinations have gone away in patients that had their pathology corrected such as the removal of a tumor. The most commonly reported hallucinations are animals, people or children, scary or deformed faces and heads, landscapes, and people walking in a line.
and daytime drowsiness. Peduncular hallucinosis has been described as a “release phenomenon” due to damage to the ascending reticular activating system
, which is supported by the sleep disturbance characteristic of this syndrome. In most cases, people are aware that the hallucinations are not real. However, some people experience agitation and delusion and mistake their hallucinations for reality.
(LGN). This inhibition may hyper-excite the LGN, inducing visual hallucinations. Lesions of the retina
and areas proximal to it can remove or alter the inputs coming in from the external environment to the visual system. Peduncular hallucinosis therefore might emanate from disturbances in distal portions of the visual system. Lesions in the frontal and temporal lobes can also lead to complex visual hallucinations because the lobes connect to the visual system via the lateral geniculate nucleus and medial pulvinar. Additionally, visual processing and salience can be disrupted by thalamic lesions which affect important structures such as the pulvinar.
The effect lesions on the brainstem have on the ascending reticular activating system (ARAS) has also been hypothesized. It was proposed that since the ARAS plays a role in consciousness and waking, the lesions of the brainstem common to peduncular hallucinosis may “disrupt ARAS impulses from the brainstem reticular formation” and consequently lead to the sleep disturbances characteristic of peduncular hallucinosis. The use of drugs such as Olanzapine
may help treat sleep disturbances as it has been found to “improve sleep continuity, sleep quality, and [to] increase slow wave sleep.”
, narcolepsy-cataplexy syndrome, delirium tremens, Lewy Body Dementia, and temporal lobe epilepsy
are more prone to complex visual hallucinations such as peduncular hallucinosis. Peduncular hallucinosis is more common in patients with a long duration of Parkinson's disease and also with a long treatment history, depression, and cognitive impairment. Paranoid delusions are common in these patients even though the hallucinations can occur during clear sensorium
.
for trigeminal neuralgia
. Her trigeminal neuralgia went away but the procedure led to hallucinations characteristic of peduncular hallucinosis. She was completely conscious at the time of her hallucinations of furniture, stars, and a ranch. The study concluded that peduncular hallucinosis does not does not require brainstem injury and that a cerebellar lesion could have been the causation.
In another study, a 50-year-old man also underwent microvascular decompression for trigeminal neuralgia. Two days after surgery he developed peduncular hallucinosis which disappeared after two days. It was concluded that the peduncular hallucinosis “was probably related to petrosal vein obliteration and was followed by venous congestion and posterior fossa edema
.” Also, to prevent peduncular hallucinosis and other complications due to venous congestion, these types of surgeries should protect the petrosal vein when possible.
An 11-year-old girl in one incident developed peduncular hallucinosis, which included disturbed sleep, after an endoscopic third ventriculostomy
was performed on her. A CT scan after the operation revealed bilateral subdural hygroma
. The hygroma was drained which improved her consciousness and the peduncular hallucinosis eventually subsided after two weeks.
A 10-year-old girl in another case had a hypothalamic astrocytoma
removed which caused a postoperative clot leading to diencephalon
and midbrain compression. After placement of an external ventricular drainage device, the girl became more oriented but developed peduncular hallucinosis which consisted of imaginary friends, birds, and an angel. A mild tranquilizer
was used to help control the hallucinations which subsided by the end of the week.
which was removed and diagnosed as fibroblastic meningioma. Post-operatively the patient was given the drugs dexamethasone
and carbamazepine
and there were no more occurrences of hallucinations. In a similar case, a 44-year-old woman admitted to the hospital displayed ataxia
, dysphonia
, and papilledema
. Following an MRI, a meningioma which had been compressing the midbrain was removed. Agitation and visual hallucinations began the day after surgery and a CT scan revealed moderate brain stem edema
. Dexamethasone and carbamazepine were administered to this patient as well, resulting in the disappearance of the agitation and hallucinations within three days. These case studies indicated that besides the lesions commonly associated with peduncular hallucinosis, meningiomas and brain stem compression can also be causes.
A 59-year-old man with a history of hypertension
—who had not been taking his antihypertensive medication for three days— experienced visual hallucinations of a waterfall with full awareness of the unreality of his visions. The patient was given aspirin
and antihypertensives which caused the hallucinations to disappear as the blood pressure was controlled. An MRI taken two days later found bilateral paramedian pontomesencephalic lesions of ischemic origin. The doctors concluded that the high blood pressure caused the lesions, which consequently led to the symptoms characteristic of peduncular hallucinosis.
In one case, a 76-year-old woman with Parkinson's disease was admitted to the hospital due to acute dyspnea
. Her visual hallucinations had been occurring for a year and were non-distressing and without bizarre delusions or auditory hallucinations. She understood that her hallucinations were not real. She displayed decreased short-term recall and attention span. The patient continued having the hallucinations despite discontinuation of the dopamine antagonist she was taking. An MRI of the brain found a hyper-intense focus adjacent to the right thalamus
. The patient was given quetiapine
which decreased the amount of hallucinations.
A 53-year-old man diagnosed with peduncular hallucinosis reported visual hallucinations of human figures, birds, flowers, and cartoon bunnies. He understood that the hallucinations were not real. His cognitive functioning was normal, except for ataxia and papilledema. A brain CT scan revealed lesions in the cerebral hemispheres and posterior cranial fossa due to a cerebellar metastatic tumor which consequently led to compression of the midbrain. He was treated with mannitol
and dexamethasone which led to the disappearance of hallucinations after 4 days.
An 8-year-old girl was admitted to the hospital due to headache, blurred vision, and difficulty walking for a period of 6 months. She had colorful visual hallucinations of snakes, frogs, and birds. She exhibited daytime somnolence and restlessness at night. A CT scan of the brain found a cerebellar pilocytic astrocytoma
which was causing posterior midbrain compression. Upon removal of the tumor, the hallucinations subsided.
is not necessary. While there is not a lot of evidence of effective pharmacological treatment, antipsychotics and anticonvulsants have been used in some cases to control hallucinations. Since peduncular hallucinosis occurs due to an excess of serotonin
, modern antipsychotics are used to block both dopamine
and serotonin receptors, preventing the overstimulation of the lateral geniculate nucleus. The drug generically called carbamazepine increases GABA
which prevents the LGN from firing, thereby increasing the inhibition of the LGN. Regular antipsychotics as well as antidepressants can also be helpful in reducing or eliminating peduncular hallucinosis.
More invasive treatments include corrective surgery such as cataract surgery
, laser photocoagulation
of the retina, and use of optical correcting devices. Tumor removal can also help to relieve compression in the brain, which consequently can decrease or eliminate peduncular hallucinosis. Some hallucinations may be due to underlying cardiovascular disease
so in these cases the appropriate treatment includes control of hypertension
and diabetes. As described, the type of treatment varies widely depending on the causation behind the complex visual hallucinations.
The French neurologist Jean Lhermitte
Jean Lhermitte
Jacques Jean Lhermitte was a French neurologist and neuropsychiatrist.He was born in Mont-Saint-Père, Aisne, son of Léon Augustin Lhermitte, a French realist painter. Following his early education at Saint-Etienne, he studied in Paris and graduated in medicine in 1907...
in 1922 first wrote about a patient with odd visual hallucinations that were associated with suggestions of brain damage involving the midbrain and the pons
Pons
The pons is a structure located on the brain stem, named after the Latin word for "bridge" or the 16th-century Italian anatomist and surgeon Costanzo Varolio . It is superior to the medulla oblongata, inferior to the midbrain, and ventral to the cerebellum. In humans and other bipeds this means it...
. After other case studies were published, this type of presentation was labelled "peduncular hallucinosis."
The accumulation of additional cases by Lhermitte and by others influenced academic medical debate about hallucinations and about behavioral neurology
Neurology
Neurology is a medical specialty dealing with disorders of the nervous system. Specifically, it deals with the diagnosis and treatment of all categories of disease involving the central, peripheral, and autonomic nervous systems, including their coverings, blood vessels, and all effector tissue,...
.
Lhermitte provided a full account of his work in this area in his book "Les hallucinations: clinique et physiopathologie" published in Paris in 1951 by Doin publishing.
Contemporary researchers, with access to new technologies in medical brain imagery, have confirmed the brain localization of these unusual hallucinations.
History
The first documented case of peduncular hallucinosis was by French neurologist and neuropsychiatrist Jean LhermitteJean Lhermitte
Jacques Jean Lhermitte was a French neurologist and neuropsychiatrist.He was born in Mont-Saint-Père, Aisne, son of Léon Augustin Lhermitte, a French realist painter. Following his early education at Saint-Etienne, he studied in Paris and graduated in medicine in 1907...
which described a 72-year-old woman’s visual hallucinations of colorfully dressed people and children which occurred at dusk. The hallucinations occurred during normal conscious state and the patient’s neurological signs were associated with those characteristic of an infarct to the midbrain and pons
Pons
The pons is a structure located on the brain stem, named after the Latin word for "bridge" or the 16th-century Italian anatomist and surgeon Costanzo Varolio . It is superior to the medulla oblongata, inferior to the midbrain, and ventral to the cerebellum. In humans and other bipeds this means it...
. Von Bogaert, Lhermitte’s colleague, named these type of hallucinations “peduncular” in reference to the cerebral peduncles as well as to the midbrain and its surroundings. In 1925, Von Bogaert was the first person to describe the pathology of peduncular hallucinosis though an autopsy of a patient. His autopsy revealed the infarction of many areas of the brain including the inferolateral red nucleus, superior colliculus
Superior colliculus
The optic tectum or simply tectum is a paired structure that forms a major component of the vertebrate midbrain. In mammals this structure is more commonly called the superior colliculus , but, even in mammals, the adjective tectal is commonly used. The tectum is a layered structure, with a...
, periaqueductal gray
Periaqueductal gray
Periaqueductal gray is the gray matter located around the cerebral aqueduct within the tegmentum of the midbrain. It plays a role in the descending modulation of pain and in defensive behaviour...
, third nerve nucleus, superior cerebellar peduncle, substantia nigra
Substantia nigra
The substantia nigra is a brain structure located in the mesencephalon that plays an important role in reward, addiction, and movement. Substantia nigra is Latin for "black substance", as parts of the substantia nigra appear darker than neighboring areas due to high levels of melanin in...
, and pulvinar
Pulvinar
The pulvinar nuclei are a collection of nuclei located in the pulvinar thalamus. The pulvinar part is the most posterior region of the thalamus....
. Later in 1932, Lhermitte, Levy, and Trelles discovered an association between peduncular hallucinosis and “pigmentary degeneration of the periaqueductal gray and the degeneration of the occulomotor nucleus.” Posterior thalamic lesions were also found to be linked to peduncular hallucinosis by De Morsier. More recently, magnetic resonance imaging
Magnetic resonance imaging
Magnetic resonance imaging , nuclear magnetic resonance imaging , or magnetic resonance tomography is a medical imaging technique used in radiology to visualize detailed internal structures...
(MRI) has been used to localize lesions in the brain characteristic of peduncular hallucinosis. In 1987, the first case of peduncular hallucinosis was reported in which MRI was used to locate a midbrain lesion.
Etiology
Peduncular hallucinosis is attributed to a range of various pathologies such as vascular and infectious midbrain, pontine and thalamic lesions, local subarachnoid hemorrhage, compression by tumors, basilar migraine, basilar vascular hypoplasiaHypoplasia
Hypoplasia is underdevelopment or incomplete development of a tissue or organ. Although the term is not always used precisely, it properly refers to an inadequate or below-normal number of cells. Hypoplasia is similar to aplasia, but less severe. It is technically not the opposite of hyperplasia...
, and following regional surgical or angiographic interventions. These pathologies are mainly near the base of the brain and the hallucinations have gone away in patients that had their pathology corrected such as the removal of a tumor. The most commonly reported hallucinations are animals, people or children, scary or deformed faces and heads, landscapes, and people walking in a line.
Symptoms
They are normally colorful, vivid images and occur during clear perception predominately at night. Lilliputian hallucinations, hallucinations in which people or animals appear smaller than they would be in real life, are common in cases of peduncular hallucinosis. Most patients exhibit abnormal sleep patterns characterized by nighttime insomniaInsomnia
Insomnia is most often defined by an individual's report of sleeping difficulties. While the term is sometimes used in sleep literature to describe a disorder demonstrated by polysomnographic evidence of disturbed sleep, insomnia is often defined as a positive response to either of two questions:...
and daytime drowsiness. Peduncular hallucinosis has been described as a “release phenomenon” due to damage to the ascending reticular activating system
Reticular activating system
The reticular activating system is an area of the brain responsible for regulating arousal and sleep-wake transitions.- History and Etymology :...
, which is supported by the sleep disturbance characteristic of this syndrome. In most cases, people are aware that the hallucinations are not real. However, some people experience agitation and delusion and mistake their hallucinations for reality.
Lesions
The lesions that disturb brainstem reticular formation or thalamic targets seem to be the source behind peduncular hallucinosis. For example, lesions affecting the dorsal raphe system can lead to hallucinations by preventing ascending inhibition to the dorsal lateral geniculate nucleusLateral geniculate nucleus
The lateral geniculate nucleus is the primary relay center for visual information received from the retina of the eye. The LGN is found inside the thalamus of the brain....
(LGN). This inhibition may hyper-excite the LGN, inducing visual hallucinations. Lesions of the retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
and areas proximal to it can remove or alter the inputs coming in from the external environment to the visual system. Peduncular hallucinosis therefore might emanate from disturbances in distal portions of the visual system. Lesions in the frontal and temporal lobes can also lead to complex visual hallucinations because the lobes connect to the visual system via the lateral geniculate nucleus and medial pulvinar. Additionally, visual processing and salience can be disrupted by thalamic lesions which affect important structures such as the pulvinar.
The effect lesions on the brainstem have on the ascending reticular activating system (ARAS) has also been hypothesized. It was proposed that since the ARAS plays a role in consciousness and waking, the lesions of the brainstem common to peduncular hallucinosis may “disrupt ARAS impulses from the brainstem reticular formation” and consequently lead to the sleep disturbances characteristic of peduncular hallucinosis. The use of drugs such as Olanzapine
Olanzapine
Olanzapine is an atypical antipsychotic, approved by the FDA for the treatment of schizophrenia and bipolar disorder...
may help treat sleep disturbances as it has been found to “improve sleep continuity, sleep quality, and [to] increase slow wave sleep.”
Correlation between other diseases
People diagnosed with Parkinson's diseaseParkinson's disease
Parkinson's disease is a degenerative disorder of the central nervous system...
, narcolepsy-cataplexy syndrome, delirium tremens, Lewy Body Dementia, and temporal lobe epilepsy
Epilepsy
Epilepsy is a common chronic neurological disorder characterized by seizures. These seizures are transient signs and/or symptoms of abnormal, excessive or hypersynchronous neuronal activity in the brain.About 50 million people worldwide have epilepsy, and nearly two out of every three new cases...
are more prone to complex visual hallucinations such as peduncular hallucinosis. Peduncular hallucinosis is more common in patients with a long duration of Parkinson's disease and also with a long treatment history, depression, and cognitive impairment. Paranoid delusions are common in these patients even though the hallucinations can occur during clear sensorium
Sensorium
The term sensorium refers to the sum of an organism's perception, the "seat of sensation" where it experiences and interprets the environments within which it lives. The term originally enters English from the Late Latin in the mid-17th century, from the stem sens-...
.
Differences from other visual hallucinations
Other visual hallucinations tend to stem from psychological disorders. Whereas a person with a psychological disorder thinks their hallucinations are real, people with peduncular hallucinosis normally know that the visual hallucinations they see are not real. Peduncular hallucinations are independent of seizures unlike some other visual hallucinations. The hallucinations also have the quality of being vivid and colorful and also tend to have some sort of animation.Case Studies
Peduncular hallucinosis is a rare occurrence so what is known comes from case studies.Peduncular hallucinosis occurring after surgery
In one study, a 68-year-old woman was diagnosed with peduncular hallucinosis after microvascular decompressionMicrovascular decompression
Microvascular decompression , also known as the Jannetta procedure, is a neurosurgical procedure used to treat trigeminal neuralgia, a pain syndrome characterized by severe episodes of intense facial pain and hemifacial spasm.-History:...
for trigeminal neuralgia
Trigeminal neuralgia
Trigeminal neuralgia , tic douloureux is a neuropathic disorder characterized by episodes of intense pain in the face, originating from the trigeminal nerve. It has been described as among the most painful conditions known...
. Her trigeminal neuralgia went away but the procedure led to hallucinations characteristic of peduncular hallucinosis. She was completely conscious at the time of her hallucinations of furniture, stars, and a ranch. The study concluded that peduncular hallucinosis does not does not require brainstem injury and that a cerebellar lesion could have been the causation.
In another study, a 50-year-old man also underwent microvascular decompression for trigeminal neuralgia. Two days after surgery he developed peduncular hallucinosis which disappeared after two days. It was concluded that the peduncular hallucinosis “was probably related to petrosal vein obliteration and was followed by venous congestion and posterior fossa edema
Edema
Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...
.” Also, to prevent peduncular hallucinosis and other complications due to venous congestion, these types of surgeries should protect the petrosal vein when possible.
An 11-year-old girl in one incident developed peduncular hallucinosis, which included disturbed sleep, after an endoscopic third ventriculostomy
Ventriculostomy
Ventriculostomy is a neurosurgical procedure that involves creating a hole within a cerebral ventricle for drainage. It is done by surgically penetrating the skull, dura mater, and brain such that the ventricle of the brain is accessed. When catheter drainage is temporary, it is commonly referred...
was performed on her. A CT scan after the operation revealed bilateral subdural hygroma
Subdural hygroma
A subdural hygroma is a subdural body of cerebrospinal fluid , without blood. Most subdural hygromas are believed to be derived from chronic subdural hematomas. It is commonly seen in elderly patients after minor trauma but can be seen in children after an infection. One of the common causes of...
. The hygroma was drained which improved her consciousness and the peduncular hallucinosis eventually subsided after two weeks.
A 10-year-old girl in another case had a hypothalamic astrocytoma
Astrocytoma
Astrocytomas are a type of neoplasm of the brain. They originate in a particular kind of glial-cells, star-shaped brain cells in the cerebrum called astrocytes. This type of tumor does not usually spread outside the brain and spinal cord and it does not usually affect other organs...
removed which caused a postoperative clot leading to diencephalon
Diencephalon
The diencephalon is the region of the vertebrate neural tube which gives rise to posterior forebrain structures. In development, the forebrain develops from the prosencephalon, the most anterior vesicle of the neural tube which later forms both the diencephalon and the...
and midbrain compression. After placement of an external ventricular drainage device, the girl became more oriented but developed peduncular hallucinosis which consisted of imaginary friends, birds, and an angel. A mild tranquilizer
Tranquilizer
A tranquilizer, or tranquilliser , is a drug that induces tranquility in an individual.The term "tranquilizer" is imprecise, and is usually qualified, or replaced with more precise terms:...
was used to help control the hallucinations which subsided by the end of the week.
Peduncular hallucinosis unrelated to surgery
A 69-year-old woman with a recent history of ataxia and intracranial hypertension experienced vivid hallucinations combined with mental confusion, agitation, and sleep disturbances. An MRI of the brain located aright tentorial meningiomaMeningioma
The word meningioma was first used by Harvey Cushing in 1922 to describe a tumor originating from the meninges, the membranous layers surrounding the CNS ....
which was removed and diagnosed as fibroblastic meningioma. Post-operatively the patient was given the drugs dexamethasone
Dexamethasone
Dexamethasone is a potent synthetic member of the glucocorticoid class of steroid drugs. It acts as an anti-inflammatory and immunosuppressant...
and carbamazepine
Carbamazepine
Carbamazepine is an anticonvulsant and mood-stabilizing drug used primarily in the treatment of epilepsy and bipolar disorder, as well as trigeminal neuralgia...
and there were no more occurrences of hallucinations. In a similar case, a 44-year-old woman admitted to the hospital displayed ataxia
Ataxia
Ataxia is a neurological sign and symptom that consists of gross lack of coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system that coordinate movement, such as the cerebellum...
, dysphonia
Dysphonia
Dysphonia is the medical term for disorders of the voice: an impairment in the ability to produce voice sounds using the vocal organs . Thus, dysphonia is a phonation disorder...
, and papilledema
Papilledema
Papilledema is optic disc swelling that is caused by increased intracranial pressure. The swelling is usually bilateral and can occur over a period of hours to weeks. Unilateral presentation is extremely rare....
. Following an MRI, a meningioma which had been compressing the midbrain was removed. Agitation and visual hallucinations began the day after surgery and a CT scan revealed moderate brain stem edema
Edema
Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...
. Dexamethasone and carbamazepine were administered to this patient as well, resulting in the disappearance of the agitation and hallucinations within three days. These case studies indicated that besides the lesions commonly associated with peduncular hallucinosis, meningiomas and brain stem compression can also be causes.
A 59-year-old man with a history of hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
—who had not been taking his antihypertensive medication for three days— experienced visual hallucinations of a waterfall with full awareness of the unreality of his visions. The patient was given aspirin
Aspirin
Aspirin , also known as acetylsalicylic acid , is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. It was discovered by Arthur Eichengrun, a chemist with the German company Bayer...
and antihypertensives which caused the hallucinations to disappear as the blood pressure was controlled. An MRI taken two days later found bilateral paramedian pontomesencephalic lesions of ischemic origin. The doctors concluded that the high blood pressure caused the lesions, which consequently led to the symptoms characteristic of peduncular hallucinosis.
In one case, a 76-year-old woman with Parkinson's disease was admitted to the hospital due to acute dyspnea
Dyspnea
Dyspnea , shortness of breath , or air hunger, is the subjective symptom of breathlessness.It is a normal symptom of heavy exertion but becomes pathological if it occurs in unexpected situations...
. Her visual hallucinations had been occurring for a year and were non-distressing and without bizarre delusions or auditory hallucinations. She understood that her hallucinations were not real. She displayed decreased short-term recall and attention span. The patient continued having the hallucinations despite discontinuation of the dopamine antagonist she was taking. An MRI of the brain found a hyper-intense focus adjacent to the right thalamus
Thalamus
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...
. The patient was given quetiapine
Quetiapine
Quetiapine , is an atypical antipsychotic approved for the treatment of schizophrenia, and bipolar disorder....
which decreased the amount of hallucinations.
A 53-year-old man diagnosed with peduncular hallucinosis reported visual hallucinations of human figures, birds, flowers, and cartoon bunnies. He understood that the hallucinations were not real. His cognitive functioning was normal, except for ataxia and papilledema. A brain CT scan revealed lesions in the cerebral hemispheres and posterior cranial fossa due to a cerebellar metastatic tumor which consequently led to compression of the midbrain. He was treated with mannitol
Mannitol
Mannitol is a white, crystalline organic compound with the formula . This polyol is used as an osmotic diuretic agent and a weak renal vasodilator...
and dexamethasone which led to the disappearance of hallucinations after 4 days.
An 8-year-old girl was admitted to the hospital due to headache, blurred vision, and difficulty walking for a period of 6 months. She had colorful visual hallucinations of snakes, frogs, and birds. She exhibited daytime somnolence and restlessness at night. A CT scan of the brain found a cerebellar pilocytic astrocytoma
Pilocytic astrocytoma
Pilocytic astrocytoma or juvenile pilocytic astrocytoma or cystic cerebellar astrocytoma is a neoplasm of the brain that occurs more often in children and young adults...
which was causing posterior midbrain compression. Upon removal of the tumor, the hallucinations subsided.
Treatment
Treatment of any kind of complex visual hallucination requires an understanding of the different pathologies in order to correctly diagnose and treat. Obviously if a person is taking a pro-hallucinogenic medication, then the first step is to stop taking it. Sometimes improvement will occur spontaneously and pharmacotherapyPharmacotherapy
Pharmacotherapy is the treatment of disease through the administration of drugs. As such, it is considered part of the larger category of therapy....
is not necessary. While there is not a lot of evidence of effective pharmacological treatment, antipsychotics and anticonvulsants have been used in some cases to control hallucinations. Since peduncular hallucinosis occurs due to an excess of serotonin
Serotonin
Serotonin or 5-hydroxytryptamine is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal tract, platelets, and in the central nervous system of animals including humans...
, modern antipsychotics are used to block both dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
and serotonin receptors, preventing the overstimulation of the lateral geniculate nucleus. The drug generically called carbamazepine increases GABA
Gabâ
Gabâ or gabaa, for the people in many parts of the Philippines), is the concept of a non-human and non-divine, imminent retribution. A sort of negative karma, it is generally seen as an evil effect on a person because of their wrongdoings or transgressions...
which prevents the LGN from firing, thereby increasing the inhibition of the LGN. Regular antipsychotics as well as antidepressants can also be helpful in reducing or eliminating peduncular hallucinosis.
More invasive treatments include corrective surgery such as cataract surgery
Cataract surgery
Cataract surgery is the removal of the natural lens of the eye that has developed an opacification, which is referred to as a cataract. Metabolic changes of the crystalline lens fibers over time lead to the development of the cataract and loss of transparency, causing impairment or loss of vision...
, laser photocoagulation
Laser photocoagulation
Laser coagulation or laser photocoagulation surgery is used to treat a number of eye diseases and has become widely used in recent decades...
of the retina, and use of optical correcting devices. Tumor removal can also help to relieve compression in the brain, which consequently can decrease or eliminate peduncular hallucinosis. Some hallucinations may be due to underlying cardiovascular disease
Cardiovascular disease
Heart disease or cardiovascular disease are the class of diseases that involve the heart or blood vessels . While the term technically refers to any disease that affects the cardiovascular system , it is usually used to refer to those related to atherosclerosis...
so in these cases the appropriate treatment includes control of hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
and diabetes. As described, the type of treatment varies widely depending on the causation behind the complex visual hallucinations.
External links
- Lhermitte's Peduncular Hallucinosis: An historical perspective (broken link, Wayback archive version) Anthony H. Risser and Frank C. Powell: Lhermitte's Peduncular Hallucinosis - An historical perspective. Paper presented at the 45th Meeting of the American Academy of Neurology. New York, 1993.