Phantosmia

What is Phantosmia?

Phantosmia is a condition where a person smells something that isn’t really there. This is different from parosmia, another smell disorder, where a person gets a false or changed sense of smell when real smells will be present.

Phantosmia is sometimes also called “olfactory hallucinations” or “phantom odors”. These smell disorders can be either conductive or sensorineural. Conductive dysfunction means a blockage is preventing smells from reaching areas in the nose responsible for sensing odors. Sensorineural dysfunction means the problem is related to the process that detects and recognizes smells.

There are different ways to classify phantosmia, like into central and peripheral. Peripheral phantosmia is thought to be caused by changes or damages to the smell-sensitive areas in our nose – or the olfactory mucosa and sensory receptors. Central phantosmia is thought to be caused by changes within our brain that interpret smells.

Living with Phantosmia can affect a person’s life in many ways. Our sense of smell is important for things like enjoying food, socializing, and being aware of dangers in our environment.

When it comes to how smells are detected and processed, our nose has a special area called the olfactory epithelium that picks up smells. Beneath this area, there are stem cells that can repair this part of the nose when needed. Above the stem cells, there are receptors that can recognize smells and send this information as signals through the olfactory nerve to our brain to create perception of these smells.

Every one of these receptors works with a specific protein, and when odors bind to this protein, the receptors send signals to an area in the brain called the olfactory bulb. Here, different nerves group together to create stable connections with other neurons in our brain.

These second-order neurons then transmit smell signals within the olfactory tract to structures such as the piriform cortex, rostral entorhinal cortex, and the periamygdaloid cortex. The smell signals are further processed in the secondary and tertiary olfactory networks, comprising of areas like the thalamus, hypothalamus, and dorsolateral frontal cortex.

What Causes Phantosmia?

Phantosmia is a condition where you smell odors that aren’t actually there. The exact cause of phantosmia isn’t known, but it’s been linked to various situations like a head injury, infections in the upper respiratory tract, aging, seizures in the temporal lobe of the brain, sinusitis, brain tumors, certain medicines, diseases like an underactive thyroid, and certain brain disorders like Parkinson’s disease. It’s also been found in people with migraine, and mental health and mood disorders like schizophrenia.

However, most of the time, there’s no clear reason for phantosmia; it’s what doctors call “idiopathic”. When trying to understand phantosmia, it’s useful to group it into two main types: those caused by issues outside the central nervous system (peripheral causes), and those caused by issues in the brain (central causes).

Imagine your sense of smell like a path. Odors have to travel along this path to reach the parts of your brain that recognize and interpret them. If there’s a blockage somewhere along this path (a conductive dysfunction), you might have trouble smelling. Alternatively, if the path is clear, but there’s a problem with the signals that your nerves send to your brain about the odor (a sensorineural dysfunction), or an issue in how your brain processes these signals (central dysfunction), this could also impact your sense of smell.

Looking closer at central causes for phantosmia, these might include a brain injury, aging, seizures in the temporal lobe of the brain, brain tumors, migraines, and mental health disorders, such as schizophrenia.

In your brain, there are specific areas, including the thalamus, hypothalamus, and the dorsolateral frontal cortex, that deal with recognizing and interpreting smells. If there’s an issue in any of these areas, it could alter your sense of smell. Similarly, if there’s a problem with the nerve cells in your nose that send information about odors to your brain (which doctors call olfactory neuroepithelium), it could cause phantosmia. For example, upper respiratory infections like COVID-19 have been associated with this condition.

A common theory for phantosmia caused by peripheral issues suggests that damage to these nerve cells in your nose followed by incorrect repair and regeneration could lead to incorrect information about smells being sent to your brain.

Risk Factors and Frequency for Phantosmia

Phantosmia, an uncommon smell disorder, accounts for 10-20% of complaints related to the sense of smell. It’s difficult to determine how many people suffer from phantosmia due to factors like under-reporting, different testing standards, and differences between different groups of people. The fact that our sense of smell can change as we age makes it even harder to compare rates of phantosmia in different populations.

• A recent survey suggested that about 6% of U.S. adults 40 or older experience phantosmia, with women being affected more often.
• Another study suggested that 4.9% of Swedish adults 60 or older suffer from phantosmia.
• Phantosmia has been linked to various conditions like epilepsy, schizophrenia, Parkinson’s disease, depression, and migraines, but the specific connections are still not well understood.

Signs and Symptoms of Phantosmia

When someone goes to the doctor with phantosmia, where the person smells something like a “burnt” odor when there’s nothing around causing the smell, the doctor typically starts their examination with a complete nose and throat examination. While a “burnt” smell is the most reported one, some patients also report other unpleasant smells such as that of feces, rotten, musty, gas or even sweet, metallic, or fruity smells.

The doctor will ask questions about the patient’s symptoms, like when they started, how often they happen, what seems to bring them on, how the patient would describe the smell, and whether anything makes it better or worse.

There are several other pieces of information the doctor needs to help diagnose and manage the condition such as:

• History of trauma to the head
• Mental health history
• Systemic health conditions
• History of radiation therapy
• History of head and neck cancer
• Medications being taken by the patient
• Alcohol use history
• Tobacco use history
• History of illicit drug use
• Environmental exposures
• Working conditions
• Allergies
• Previous surgeries
• Family medical history
• Recent upper respiratory tract infections
• History of migraines
• History of seizures
• History of sinusitis, nasal polyps, sinus surgery, or previous head imaging

Testing for Phantosmia

When you experience phantosmia, which means you’re smelling things that aren’t actually there, your doctor will ask you for a detailed medical history and conduct a physical exam. This helps them gain information about possible reasons behind your condition.

If they suspect that the cause might be something like chronic sinusitis (long-term inflammation of the sinuses) or nasal polyps (small, benign growths in the nose), a nasal endoscopy might be performed. This is a procedure where a flexible tube with a camera on the end is inserted into your nose, allowing the doctor to closely examine the area.

If your doctor cannot find an obvious cause, they might also use imaging techniques to examine your body further. A computed tomography scan (CT scan for short), which is a kind of X-ray that provides detailed images of the body, may be used to examine your sinuses. Likewise, a magnetic resonance imaging scan (MRI for short), a type of scan that uses magnetic fields and radio waves to produce detailed images of the inside of the body, might be used to examine your brain, particularly focusing on the area related to sense of smell.

An MRI of the brain can help identify problems like tumors, growths, or strokes, while a sinus CT scan can reveal issues like chronic sinusitis, nasal polyps, or masses in the nose and sinuses – all of which could be contributing to your phantosmia.

In general, doctors often categorize smell disorders into two groups. The first, quantitative olfactory disorders, includes conditions like anosmia or hyposmia, where there’s a loss or reduction in your ability to smell. The second, qualitative olfactory disorders, includes conditions like parosmia or phantosmia, where your sense of smell is distorted or altered.

There are reliable tests for measuring quantitative olfactory disorders. However, there’s no standard, universally accepted test for measuring qualitative changes to smell, which makes these conditions more challenging to diagnose.

Treatment Options for Phantosmia

Phantosmia, or the condition where you smell something that isn’t there, can be hard to treat and understand. This is because there isn’t a lot of information about its treatment and management. However, doctors agree that the first step is to determine and treat whatever is causing the phantosmia. For that reason, a detailed examination and investigation may be necessary.

Some of the methods that have been discussed for treating cases of phantosmia rooted in the brain include the use of certain medications like antipsychotics, anticonvulsants, and antidepressants. If the phantosmia is coming from the nose, the aim would be to stop the receptors in the nasal lining (olfactory mucosa) from causing a smell when there’s no odor-producing stimulus. This can be achieved by a local anesthetic, like cocaine, or surgically removing the olfactory mucosa, which involves the removal of a part of the nasal lining responsible for smell.

However, studies have shown that the effect of local anesthetic drugs on the nasal lining is not long-lasting. On the other hand, a small study found that some patients experienced long-term relief from phantosmia after part of their nasal lining was surgically removed. In three such cases, this relief from their symptoms lasted for a significantly long time.

Due to advances in nasal endoscopy, which is a procedure that allows doctors to look at the inside of the nose and sinus passages, this surgery has become safer. But it’s important to note that there are still risks involved, including leakage of cerebrospinal fluid (fluid found in the brain and spinal cord), bleeding, and potential damage to surrounding structures. For these reasons, surgery is usually considered only when other medical treatments have been ineffective and the phantosmia is severely reducing the patient’s quality of life.

A recent review of different treatments for phantosmia suggested that outcomes can vary depending on the cause of the condition. For example, phantosmia that occurred during migraine headaches was often resolved with migraine prevention therapy. Most patients who underwent surgical removal of the affected nasal lining also experienced relief from their symptoms.

Another method, transcranial stimulation (a technique that sends electrical signals to the brain), was shown to be very effective for short-term relief, but it didn’t offer significant long-term improvement. Overall, the review suggested that treatments targeting the root cause of the phantosmia were generally more beneficial. However, it must be noted that there are no robust treatment guidelines because there isn’t enough research on this topic, and more studies are necessary.

In conclusion, treating and managing phantosmia depends on the individual patient’s condition and what specifically is causing their phantosmia. A careful investigation into the cause of phantosmia will help guide its management. Since our understanding of phantosmia is limited and there’s urgency for more research, the treatment approaches may evolve over time.

What else can Phantosmia be?

There are a number of conditions that can cause changes in your sense of smell or lead to smell disorders. These include:

• Parosmia – a condition where your sense of smell is distorted
• Hyposmia – a reduced ability to smell
• Anosmia – the loss of the sense of smell
• Brain mass – a growth in the brain
• Temporal lobe seizures – a type of epilepsy that occurs in the temporal lobe of the brain
• Schizophrenia – a mental health disorder that affects how a person thinks, feels, and behaves
• Mood disorders – mental health conditions that affect your emotional state
• Upper respiratory tract infection – an infection in the airways leading to your lungs
• Nasal or paranasal sinus disease – diseases affecting the nose and spaces surrounding it
• Chronic rhinosinusitis – long-term inflammation of the sinuses and nasal cavity
• Nasal polyposis – small growths in the nose
• Migraine – a type of headache that can cause severe throbbing pain
• Epilepsy – a neurological disorder that causes seizures
• Neurodegenerative disease – diseases that result in the loss of structure or function of nerve cells

What to expect with Phantosmia

Phantosmia, like other disorders related to the sense of smell, tends to worsen over time. However, compared to other similar disorders, such as parosmia, people with phantosmia often recover naturally at a faster rate.

While many treatments have been suggested for phantosmia, their effectiveness varies and there’s limited evidence that they improve patient outcomes. In the past, we thought the cause of the phantosmia could predict how well a patient might do. For example, phantosmia resulting from a traumatic injury was believed to have a worse outcome than that caused by an upper respiratory infection. This belief, however, is now being questioned.

Now, it’s believed that things like age, whether a person smokes, and how severe the disease is may predict the patient’s outcome. So, younger, non-smoking people with severe disease might have better outcomes. This could be because these individuals might have a greater ability to regenerate the cells lining the nose (neuroepithelium).

When managing phantosmia, it’s crucial to address the underlying cause. Doing so often leads to the resolution of the smell impairments.

Possible Complications When Diagnosed with Phantosmia

Phantosmia may not have serious physical complications, but it can lead to serious problems in a person’s life. It can make someone feel isolated, lose their ability to feel pleasure, become depressed, and develop anxiety. Working with a team of healthcare professionals, including mental health experts, is critical for people suffering from this condition. Trying to treat the condition can also come with problems. Certain drugs used for psychosis, migraines, and seizures can have side effects.

In severe cases, doctors might suggest removing parts of the nose that help with smell. This surgery comes with its own risks, like cerebrospinal fluid leak, damage to the skull or eye, and bleeding. Doctors always need to make sure patients understand the risks and benefits before starting treatment. These issues can become worse if healthcare professionals dismiss a patient’s symptoms. Problems with smell require the same attention as problems with sight and hearing. An appropriate reaction from healthcare professionals can help avoid problems for patients and create a trust-filled relationship between patients and doctors.

Possible Complications:

• Social isolation
• Inability to feel pleasure
• Depression
• Anxiety
• Side effects from medication
• Risks from surgery

Preventing Phantosmia

Dealing with phantosmia, a condition where you smell odors that aren’t actually present, can be tough because there aren’t too many treatment options available. However, understanding the underlying causes and being properly educated about the condition can help manage the distressing effects. This is proven in cases where phantosmia was found to be a result of migraines, seizures, or schizophrenia, and the symptoms got better when the main health issue was addressed.

The spectrum of smell disorders is broad, and helping patients understand their specific condition can help them tell the difference between phantosmia and other smell-related problems. This understanding can guide further assessment and treatment. Knowing the potential cause, if any, behind a person’s phantosmia can support them in seeking appropriate treatment and possibly finding relief from symptoms. Phantosmia can severely impact a person’s quality of life, making it extremely important for healthcare providers to understand the condition and its causes, assessments, and management, so they can provide effective patient education.