Visual Hallucinations: Don't Assume It's Psychiatric

This transcript has been edited for clarity.When you hear that somebody is having a visual hallucination, your first thought is probably that they are psychotic, or that they are having some other psychiatric illness. But visual hallucinations often occur in other physical illnesses. So, let's talk about the differential diagnosis for visual hallucinations beyond simply psychosis.I'm Dr Adjoa Smalls-Mantey, an emergency psychiatrist, and many times I will see patients come to the emergency room with visual hallucinations. In my experience, in about 80% of those cases, they aren't having simply a psychiatric illness, and there is something else going on. Whenever someone presents with hallucinations, that gives me cause for concern. There's something else that we must rule out that could be a lot more serious.What Is a Visual Hallucination?Before we get into what those can be, first, let's define what a visual hallucination is.Now, a hallucination is a false sensory experience, and when you have a visual hallucination, that means that you are seeing something. "Your eye is playing tricks on you?" is how I will often ask people. People can have simple visual hallucinations, or they can have complex visual hallucinations.A simple visual hallucination might be something like seeing a geometric shape, maybe some lines, light might look a little bit funny, maybe squiggly lines.But a complex visual hallucination is something that is fully formed, like seeing a person, seeing an animal, seeing an object.Causes of Visual HallucinationsWhat are some of the different physical illnesses or other causes of a visual hallucination?Eye and Retina ConditionsThe first group of causes includes diabetic retinopathy, macular degeneration, retinal detachment, or even cerebral infarct. The person usually is aware that they are having a problem with their vision, and that whatever they're seeing is not real.You even have Charles Bonnet syndrome, where people have a fully formed image of seeing something, and that may be due to a lesion somewhere along the optic tract, and their brain is trying to replace an image that they think should be there.Whenever somebody is suspected of retinopathy, you should request an ophthalmology consult immediately.Migraine With AuraThe second way that people might have a visual hallucination is in a migraine with aura. About 15%-33% of people that have migraines have auras, and about 90% of those auras involve visual symptoms. People might see zig-zag lines or have scintillating scotoma, where you have a sort of blind field and then a zig-zag region around it. People might see flashing dots. But then also people can have distortions that look like tunnel vision or heat waves.Now, in a migraine aura, the symptoms will usually start centrally and then move to the periphery. They'll last about 5-60 minutes, and they're usually in discrete episodes. Patients will have at least two episodes. Then they move on to having the migraine accompanied by nausea, vomiting, and photophobia.This can be very distressing for people when that first happens. But when it starts happening to someone that has had past migraines, they're more able to handle and even prepare for the migraine.EpilepsyThe third condition in which people can have visual hallucinations is epilepsy. In epilepsy, depending on where your seizure focus is, that can determine the nature of your visual hallucination.If you are having a seizure focus in the occipital lobe, it can be more of a simple visual hallucination. If your seizure focus is in the temporal lobe, you can have more of a complex visual hallucination.These usually last for only a few seconds, but if a patient is in status epilepticus, it can go on for much longer. The way to diagnose this is through an EEG.DementiaThe fourth instance in which somebody might have visual hallucinations is in certain types of dementia. Primarily, in Lewy body dementia, somebody will have a well-formed complex visual hallucination, and it usually is early in the start of their disease, along with some behavioral disinhibition and other symptoms that then produce parkinsonism.In these cases, a family member might come to me and describe somebody pointing to something on the floor, seeing something. They've been very temperamental. They're having a little bit of memory issues.The person might even right in front of me say, "Oh, I see this object right there." A lot of times it tends to be animals or little children, and there was nobody there. That is very classic in Lewy body dementia.When it comes to Parkinson's disease, we are often treating people with agents that help their movement, but these agents can also bring on visual hallucinations, mainly levodopa. Although somebody is having visual hallucinations and we often think we need to block the dopamine, that can make their Parkinson's disease worse.However, there is a medication called pimavanserin, which is a 5-HT2A receptor inverse agonist that is used to treat psychosis in Parkinson's disease.In other dementias, visual hallucinations are less common, so you don't see them as much in patients with Alzheimer's disease or frontotemporal dementia.Brain PathologiesThe fifth instance in which you will also see visual hallucinations is in cases of brain pathology, and those brain pathologies can be vast. Sadly, I've had the occasion where a person has come with new onset visual hallucinations, and it has been an indicator of tumors, maybe a metastasis from another region. So, you do want to order a CT scan or a brain MRI.A visual hallucination can also occur in a stroke depending on the region of the brain that's affected.Also, you can have metabolic encephalopathies. So when somebody is uremic or has hepatic encephalopathy, hypoxemia, hyperglycemia, those can also cause visual hallucinations.And even in infectious diseases or autoimmune diseases, especially herpes encephalitis or anti-NMDA receptor encephalitis, a person might suffer from visual hallucinations.NarcolepsyNarcolepsy is another instance in which somebody can have visual hallucinations, and it is thought to be due to REM sleep intruding on wakefulness. You can have hypnopompic hallucinations, hallucinations that happen when you are waking up, or hypnagogic hallucinations that occur when you are falling asleep.Medications, Substance Use, and WithdrawalThe seventh category that I want to talk about in which visual hallucinations can occur is drug intoxication, withdrawal, or even taking regular medications. Most commonly, you will probably see visual hallucinations in the case of alcohol or benzodiazepine withdrawal.I have had patients literally describe a whole landscape that they are seeing right in front of me, although it is not there. That is a serious emergency. Likely they are in very serious withdrawal. You want to have them on a medically supervised benzodiazepine taper for that type of withdrawal if they are starting to have visual hallucinations.You can also have visual hallucinations with other intoxicants: LSD, psilocybin, cocaine, methamphetamine, mescaline. Ask patients if they have taken any illicit drugs and order a urine toxicology screen.Medications that can cause visual hallucinations include levodopa because excess dopamine can disrupt visual processing and perception networks. You also have levetiracetam (Keppra) where visual hallucinations are rare and usually occur when people are first starting on the medication. As you increase the doses, people might describe seeing very complex images, often involving animals.Also, digoxin toxicity can cause visual disturbances. Maybe not full complex visual hallucinations, but people might describe seeing a yellow tinge to items or that they're having photophobia.Psychiatric IllnessesFinally, the eighth instance in which you can have visual hallucinations is in psychiatric illnesses. People with schizophrenia may experience visual and auditory hallucinations. You can also see visual hallucinations in depression with psychotic features or mania.Whenever somebody comes into your practice or into the emergency room describing visual hallucinations, don't just write it off as a psychiatric illness. It could be an indicator of a much more serious underlying physical condition that needs rapid treatment as well. Assessing Visual HallucinationsObtain a thorough medical history to make sure that there aren't any offending medications or illnesses that they might have had and ask about predispositions and family history of dementia.Make sure you also do a thorough physical assessment.Order basic labs, a urine toxicology, and if you think it's indicated, a head CT or a brain MRI. You want to do a fundoscopic exam as well.Thank you.Adjoa Smalls-Mantey, MD, DPhil, is an assistant clinical professor of psychiatry at Columbia University and an adjunct assistant professor of psychiatry at NYU Grossman School of Medicine in New York. She serves as president of the New York County Psychiatric Society and has held multiple leadership roles within the New York City district branch. Dr Smalls-Mantey has authored numerous scientific publications and contributes to ABC News as part of its medical unit. She is also an active speaker in community and media forums on mental illness, wellness, and public health.