Differential Diagnosis for Severe Unilateral Headache
Single Most Likely Diagnosis
- Cluster Headache: This condition is characterized by severe, unilateral headaches that often occur at the same time every day, typically during certain seasons (e.g., spring). The pain is usually centered around one eye and can be accompanied by other symptoms like nasal congestion and eye watering. The seasonal pattern and nighttime occurrence of the headache in the question align with cluster headache characteristics.
Other Likely Diagnoses
- Migraine: Migraines can cause severe, unilateral headaches, although they are not exclusively nighttime occurrences. They can be triggered by various factors, including seasonal changes, and are often accompanied by other symptoms like sensitivity to light and sound.
- Sinusitis: Inflammation of the sinuses can cause pain over the affected area, which could be perceived as a headache. Given the location over the left eye, frontal sinusitis could be a consideration, especially if the patient experiences other symptoms like facial pain or nasal discharge.
Do Not Miss Diagnoses
- Temporal Arteritis (Giant Cell Arteritis): Although less common, this condition is critical to consider due to its potential for serious complications, such as blindness. It typically affects older adults and can cause severe, unilateral headaches, often accompanied by jaw claudication and visual disturbances.
- Acute Angle-Closure Glaucoma: This is an ophthalmologic emergency that can cause severe, unilateral eye pain, often accompanied by blurred vision, nausea, and vomiting. It requires immediate medical attention to prevent permanent vision loss.
Rare Diagnoses
- Trigeminal Neuralgia: This condition involves sudden, severe, shock-like pain around the eyes, lips, or nose mainly because of abnormal blood vessels pressing on the trigeminal nerve in the head. While it's a possibility, it's less likely given the specific description of the headache being over one eye and occurring at night.
- Hemicrania Continua: A rare form of headache disorder characterized by a continuous, unilateral headache with periods of exacerbation. It's an unlikely diagnosis but should be considered if other, more common conditions are ruled out.