BENGALURU: Parkinson’s disease (PD) is a neurodegenerative disease of the brain. Like other neurodegenerative diseases, it can affect the brain as a whole, this disease has a predilection to certain group of nerve cells that produce dopamine.
Parkinson’s disease is commonly remembered as the disease of tremors. Not just related to tremor or movement, it causes lot of other symptoms which are referred to as non-motor symptoms which may precede the onset of tremor and slowness by even more than 10 years. These include primary diseases, like reduced smell sense, sleep disturbances (insomnia, frightening dreams, enacting dreams), memory loss, depression, constipation, difficulty in holding urine, and even sexual dysfunction.
Hallucinations are sensations that seem real but are created in a person's mind. A person having a hallucination may see, hear or feel things that are not actually happening.
Visual hallucination is one of the most distressing symptoms for any patient; it becomes especially more distressing when the patient believes that it is true. The visual hallucination may range from very simple unformed to very vivid visual hallucinations causing significant anxiety to patient as well as his caretakers. At times, patients may shy away from reporting them, thinking that they will be branded as ‘insane’.
According to the National Parkinson Foundation, visual hallucinations can be a complication of Parkinson's disease. Over the course of PD, visual hallucinations are frequently reported (17 to 72 per cent). Any Parkinson’s disease patient would have a lifetime risk of around 45 per cent of getting visual hallucination.
Causes of visual hallucinations in PD:
a) Disease induced: The factors which increase the chance of having disease induced visual hallucination are presence of cognitive impairment, higher stage of PD, longer duration of the disease, presence of depression and sleep alterations.
b) Drug induced: There are various types of medications given for PD, which also differ in their capacity to produce visual hallucination. The most commonly implicated drugs are amantadine, pramipexole and levodopa.
Visual hallucinations may be minor or complex:
a)Minor visual hallucination:
1) Presence hallucination: Feeling ‘someone is beside or behind’
2) Passage hallucinations: Feeling ‘some animal or some person just passed by’
3) String hallucination: Patient may find that there are long strands of thread or skin extending from the fingers
b) Complex visual hallucination:
1) Formed visual hallucination: Clearly seeing nonexistent human/devils/other peculiar creatures. Many a times patients get the feel of living in a fantasy world and at times may even tend to interact with them.
2) Multimodal hallucination: Along with visual hallucination the patient may also hear a nonexistent person speak to them, feel someone is touching and perceive nonexistent odours like some aromatic food.
Role of a neurologist in managing visual hallucination: Whenever a patient with PD develops visual hallucination, the nature of hallucination, severity and its probable etiology, a detailed history including the duration of the disease, severity and stage, presence of cognitive decline and detailed drug history is required. There are lots of diseases other than Parkinson’s disease which can be present with visual hallucination which your neurologist has to rule out. In fact, if visual hallucination occurs within one year of course of the disease, then other diseases may also be considered like Dementia with Lewy Bodies (DLB).
Treatment: Depending on the scenario, the visual hallucination might respond to dose adjustment of parkinsonian medication. Medications like amantadine, and pramipexole have strong predilection to cause visual hallucination which may respond promptly to dose reduction.
Non-drug related visual hallucination may require addition of some other medications like acetylcholineesterase inhibitors and antipsychotics. As antipsychotic drugs can worsen parkinsonism, only the safer antipsychotics like clozapine, quetiapine, and the like are used.
Role of patient and care givers in managing of visual hallucination: Patients and their bystanders need to be aware of this entity. Many a times patients do not report it considering that they might be branded as ‘insane’. Patients should be encouraged to speak up regarding any such symptoms especially with family members and report to the doctor at the earliest so that appropriate measures to manage the same may be initiated. The medications for the visual hallucination may need to be titrated slowly and patients should be understood the need for multiple visits for the initial dose of titration to minimise the drug related side effects.
To conclude, visual hallucination of Parkinson’s disease requires much more attention and awareness among the patients, and their caregivers. Timely intervention by experts (movement disorder specialists/neurologists) may help prevent significant morbidity to patient and stress to care givers.
(The author is a consultant neurologist at Narayana Health City)