Differential Diagnosis
The patient's symptoms of tingling on the left side of his face, dilation of the left pupil, abnormal extraocular movement of the left eye, drooping of the left eyelid, and light sensitivity, along with the CT scan findings, suggest a complex neurological condition. Here is a categorized differential diagnosis:
- Single most likely diagnosis
- Cerebral aneurysm: The patient's symptoms, including the dilation of the left pupil, abnormal extraocular movement, and drooping of the left eyelid, are consistent with a third cranial nerve (oculomotor nerve) palsy, which can be caused by a cerebral aneurysm, particularly one located at the junction of the posterior communicating artery and the internal carotid artery. The CT scan findings of a well-defined and circumscribed structure with mild focal dilation in the region of the posterior communicating artery support this diagnosis.
- Other Likely diagnoses
- Migraine: Although less likely, migraines can cause neurological symptoms, including tingling, visual disturbances, and sensitivity to light. However, the presence of a third cranial nerve palsy and the CT scan findings make this diagnosis less probable.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Cerebral aneurysm (already discussed): It is crucial to prioritize the diagnosis of a cerebral aneurysm due to its potential for rupture, which can lead to severe consequences, including subarachnoid hemorrhage, stroke, and death.
- TIA (Transient Ischemic Attack): Although the patient's symptoms have been present for three weeks, which is longer than the typical duration of a TIA, it is essential to consider this diagnosis, as TIAs can be a warning sign for a future stroke.
- Rare diagnoses
- Complex partial seizure: This diagnosis is less likely, as the patient's symptoms do not typically present as a seizure disorder. However, it is essential to consider this possibility, especially if the patient has a history of seizure disorders or if other diagnostic tests are inconclusive.
- Bell’s palsy: This condition typically presents with unilateral facial weakness, which is not the primary symptom in this patient. The presence of a third cranial nerve palsy and the CT scan findings make this diagnosis unlikely.