Differential Diagnosis for Mr. M's Headaches

Single Most Likely Diagnosis

• Migraine: This is the leading hypothesis due to the description of throbbing pain behind one eye, associated nausea, and occasional vomiting. The increase in frequency and severity of headaches also aligns with migraine characteristics.

Other Likely Diagnoses

• Cluster Headaches: Although less common, cluster headaches could be considered due to the severe, unilateral pain and potential for nausea and vomiting. However, the lack of specific clustering patterns and the presence of nausea and vomiting make migraine more likely.
• Tension-Type Headaches: While less severe than migraines, tension-type headaches could be a consideration if Mr. M's headaches were not as severe or frequent. However, the description of throbbing pain and associated symptoms points more towards migraine.
• Chronic Daily Headache: Given the increase in frequency, chronic daily headache could be a consideration, but the specific characteristics of the headaches (unilateral, throbbing, with nausea and vomiting) suggest migraine.

Do Not Miss Diagnoses

• Giant Cell Arteritis: This condition, although less likely, is critical to rule out due to its potential for serious complications, including vision loss. The age of the patient and the severity of headaches could raise suspicion, but the lack of other systemic symptoms (like jaw claudication or fever) makes it less likely.
• Subarachnoid Hemorrhage or Other Intracranial Hemorrhages: Although the description does not strongly suggest a hemorrhagic event (e.g., sudden onset, "thunderclap" headache), any severe headache warrants consideration of these life-threatening conditions.
• Brain Tumor: A brain tumor could cause increased intracranial pressure leading to headaches, but the specific pattern and associated symptoms described are more typical of migraine. However, a change in headache pattern or severity could prompt investigation.

Rare Diagnoses

• Trigeminal Neuralgia: Characterized by intense, shock-like or stabbing pain in parts of the face, this condition is less likely given the description of throbbing pain and associated nausea and vomiting.
• Hemicrania Continua: A rare headache disorder with continuous, often unilateral pain, which could be considered if the headache pattern were more constant rather than episodic.
• Cervicogenic Headache: Originating from the cervical spine, these headaches could be a consideration but are less likely given the specific characteristics and location of Mr. M's pain.

Tests to be Ordered

Given the differential diagnosis, initial tests should focus on ruling out the "Do Not Miss" diagnoses and confirming the most likely diagnosis:

• Imaging: An MRI of the brain to rule out structural abnormalities such as tumors or vascular malformations.
• Blood Work: Erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) to evaluate for giant cell arteritis, especially if there are other suggestive symptoms.
• Neurological Examination: A thorough neurological exam to assess for any focal neurological deficits.
• Migraine-Specific Questionnaire: Utilize a migraine diagnostic tool to further support the diagnosis of migraine based on the patient's symptoms and history.

These tests and examinations will help in solidifying the diagnosis and guiding appropriate treatment, while also ensuring that critical, potentially life-threatening conditions are not overlooked.