From the Guidelines
The most appropriate diagnostic study at this time is E) No diagnostic study is indicated. The patient's presentation is classic for trigeminal neuralgia, characterized by paroxysmal, electric shock-like pain in the distribution of the trigeminal nerve (in this case, the maxillary branch) 1. Key features supporting this diagnosis include the brief, severe pain episodes triggered by innocuous stimuli like tooth brushing and cold water, the unilateral nature of the pain, and the specific location in the face. The normal MRI already performed helps rule out structural causes such as tumors or multiple sclerosis lesions affecting the trigeminal nerve.
According to the guidelines for management of facial pain, a careful history is essential for accurate diagnosis, and the commonest non-dental pains are temporomandibular disorders (TMDs) and neuropathic pain, with trigeminal neuralgia being a classic example of the latter 1. The evidence suggests that well-designed clinical trials of facial pain are needed, but in this case, the clinical presentation is so characteristic of trigeminal neuralgia that additional diagnostic studies would not add value to the diagnosis or management at this point 1.
Treatment typically begins with anticonvulsant medications like carbamazepine or oxcarbazepine, which are considered first-line therapy for this condition. The patient's symptoms, such as the severe, intermittent, left-sided facial pain, and the fact that ibuprofen relieved the pain for 2 hours, but the pain recurred, are all consistent with trigeminal neuralgia. Therefore, no further diagnostic study is necessary, and treatment should be initiated based on the clinical diagnosis.
From the Research
Diagnostic Approach
The patient's symptoms of severe, intermittent, left-sided facial pain, described as "an electric jolt that turns on and off every minute," are suggestive of trigeminal neuralgia. Given the sudden onset and the fact that the pain is localized to the left premolar area of the upper dental arch, it is essential to consider the possible causes of this condition.
Possible Causes and Diagnostic Studies
- Trigeminal neuralgia can be caused by vascular compression of the trigeminal nerve, which can be detected using high-resolution MRI 2.
- The study by 2 found that 3T MRI using 3D T2-weighted DRIVE in combination with 3D TOF-MRA and 3D T1-weighted gadolinium-enhanced sequences was reliable in detecting neurovascular compression and predicting the degree of root compression.
- However, given the patient's symptoms and the fact that MRI of the brain shows no abnormalities, it may be necessary to consider other diagnostic studies to rule out other possible causes, such as arteriovenous malformations (AVMs) or aneurysms.
- CT angiography has been shown to be highly sensitive in detecting cerebral AVMs and associated aneurysms, particularly those measuring less than 3cm 3, 4.
- The study by 4 found that CT angiography had a sensitivity of 90% in detecting AVMs, and was particularly useful in detecting associated aneurysms, with a sensitivity of 88%.
Most Appropriate Diagnostic Study
Based on the patient's symptoms and the fact that MRI of the brain shows no abnormalities, the most appropriate diagnostic study at this time would be CT angiography of the head. This study would help to rule out other possible causes of the patient's symptoms, such as AVMs or aneurysms, and would provide valuable information for further management.
- CT angiography is a non-invasive and relatively quick procedure that can provide detailed images of the blood vessels in the head, making it an ideal choice for detecting vascular abnormalities.
- The patient's symptoms and medical history, including hypertension and a family history of multiple sclerosis, do not necessarily suggest a specific diagnostic study, but CT angiography is a reasonable next step given the clinical presentation.