From the Guidelines
The workup for phantosmia should begin with a thorough history and physical examination, focusing on the onset, duration, and characteristics of the phantom smells, and should include a comprehensive evaluation to rule out underlying conditions such as sinonasal disease, post-viral olfactory dysfunction, traumatic brain injury, neurodegenerative disorders, seizures, psychiatric disorders, or medication side effects. The initial evaluation should include a complete head and neck examination, with special attention to the nasal cavity and sinuses. Key components of the workup include:
- Laboratory tests: complete blood count, metabolic panel, and thyroid function tests to rule out systemic causes 1
- Imaging studies: MRI of the brain is the preferred modality to evaluate for intracranial pathology such as tumors, particularly those affecting the olfactory bulb, temporal lobe, or orbitofrontal regions
- Formal olfactory testing using standardized smell identification tests to quantify any associated olfactory dysfunction
- Nasal endoscopy to directly visualize the nasal cavity and olfactory cleft
- Electroencephalography (EEG) if seizure activity is suspected, particularly temporal lobe epilepsy which can present with olfactory hallucinations
- Psychiatric evaluation if the phantosmia appears related to psychiatric conditions. It is essential to note that the provided evidence 1 does not directly address the workup for phantosmia, but the recommended approach is based on general medical knowledge and the importance of a comprehensive evaluation to determine the underlying cause of phantosmia.
From the Research
Phantosmia Workup
- Phantosmia is a condition where a person experiences a phantom smell, which can be distressing and affect their quality of life 2.
- The workup for phantosmia typically involves a thorough medical history, physical examination, and diagnostic tests to rule out any underlying conditions that may be causing the symptoms.
Diagnostic Approaches
- One study found that a full-thickness "plug" of olfactory epithelium from under the cribriform plate, including all the fila olfactoria, was excised, which eliminated the phantosmia and preserved olfactory ability in a patient 2.
- Another study used transcutaneous electrical nerve stimulation (TENS) to treat phantom pain and stump pain following amputation, but the effectiveness of TENS for phantosmia is unknown due to lack of research 3.
- Local anesthetic lidocaine was used to treat phantom limb pain, which may be relevant to phantosmia, as it was found to rapidly and reversibly extinguish phantom limb sensation 4.
Treatment Options
- The removal of abnormal peripheral olfactory neurons from the nose or the interruption of incoming signals to the olfactory bulb may be an effective treatment for phantosmia 2.
- Targeting the dorsal root ganglia (DRG) may be a potential treatment option for phantosmia, as it has been found to be effective in treating phantom limb pain 4.
- Radiation-induced phantosmia has been reported in patients receiving proton beam therapy, particularly those receiving craniospinal irradiation (CSI) 5.