Differential Diagnosis
- Single most likely diagnosis
- Vasovagal syncope: This is the most likely diagnosis given the patient's symptoms of feeling "woozy," nausea, and visual loss (described as "everything turning gray") before passing out, especially in a crowded and potentially stressful environment like a concert. The brief stiffening of the patient's arms and legs could be a part of the syncopal episode. Vasovagal syncope is common in young adults and is often triggered by stress, pain, or prolonged standing.
- Other Likely diagnoses
- Hypoglycemia: Although the patient's glucose level is 69 mg/dL, which is slightly below the normal range, the symptoms described could fit a hypoglycemic episode, especially the visual disturbances and loss of consciousness. However, the glucose level is not severely low, and other symptoms like confusion or agitation before the loss of consciousness are not mentioned.
- Absence seizure: This could be considered given the brief loss of consciousness and the description of the patient becoming unresponsive for a short period. However, absence seizures typically do not have a prodrome like feeling "woozy" or nausea and are not usually triggered by environmental factors like crowds.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Cardiac arrhythmias (e.g., Sick sinus syndrome): Although less likely given the patient's age and lack of cardiac history, cardiac causes of syncope can be life-threatening. The normal physical examination and lack of other symptoms make this less likely, but it should always be considered in the differential diagnosis of syncope.
- Partial seizure with secondary generalization: While the brief stiffening could suggest a seizure, the context (crowd, standing, prodromal symptoms) and the quick recovery without post-ictal confusion make this less likely. However, missing a seizure disorder could have significant implications for the patient's safety and treatment.
- Rare diagnoses
- Other metabolic disorders: Rare metabolic disorders could cause loss of consciousness, but given the information provided (normal physical exam, negative toxicology screen, and the specific context of the event), these would be less likely and more appropriate to consider if initial evaluations and treatments do not lead to a clear diagnosis.