Differential Diagnosis for Patient Reporting Crawling Sensation on Scalp and Brain
Single Most Likely Diagnosis
- Delusional Parasitosis: This condition is characterized by a fixed, false belief that one is infested with parasites, which could explain the sensation of something crawling on the scalp and brain. The normal CT scan of the brain supports a psychiatric rather than a neurological cause.
Other Likely Diagnoses
- Ekbom's Syndrome (Delusional Infestation): Similar to delusional parasitosis, this involves a delusional belief of being infested, but it can also include the belief of infestation in other parts of the body, not just the skin.
- Neurotic Excoriations (Psychogenic Pruritus): This condition involves excessive scratching due to a psychological cause, which could lead to sensations that might be interpreted as crawling.
- Tactile Hallucinations: These can occur in various psychiatric conditions, including schizophrenia, where patients might feel sensations on their skin without any physical stimulus.
Do Not Miss Diagnoses
- Neurosyphilis: Although less common, neurosyphilis can cause a wide range of neurological and psychiatric symptoms, including delusions and hallucinations. It's crucial to rule out this condition due to its severe consequences if left untreated.
- Lyme Disease: Neurological manifestations of Lyme disease can include a variety of symptoms, and while less likely, it's a condition that should not be missed due to its potential for serious complications.
- Vitamin B12 Deficiency: This deficiency can lead to neurological symptoms, including formication (the sensation of ants crawling on the skin), making it a critical diagnosis not to overlook.
Rare Diagnoses
- Formication due to certain medications: Some medications can cause formication as a side effect. This would be rare but should be considered, especially if the patient has recently started new medications.
- Diabetic Neuropathy: Although more commonly associated with pain, numbness, or tingling, in rare cases, diabetic neuropathy can cause formication.
- Heavy Metal Poisoning (e.g., Mercury): Exposure to certain heavy metals can lead to neurological symptoms, including formication, though this would be a rare occurrence.