Ropinirole withdrawal or dose-related effect: The patient's episodes of "blackouts" characterized by preserved consciousness but inability to move or speak, particularly occurring after missed doses of ropinirole, suggest a potential link to the medication. Ropinirole, a dopamine agonist used for restless legs syndrome, can cause various side effects, and its withdrawal or fluctuating levels might lead to such episodes.

Seizures: Although the patient's consciousness is preserved, certain types of seizures, such as complex partial seizures or focal seizures with impaired awareness, could present with an inability to move or speak. The recent episodes and the patient's medical history, including a gunshot wound to the face with residual metallic debris, might contribute to a seizure disorder.
Psychogenic Nonepileptic Seizures (PNES): Given the patient's history of major depressive disorder, even if in remission, and the psychological impact of his medical conditions, PNES should be considered. These episodes can mimic seizures but are related to psychological distress rather than neurological dysfunction.
Sleep Disorders: The patient's history of restless legs syndrome and the timing of some episodes (following missed bedtime doses of ropinirole) might suggest a sleep disorder, such as sleep paralysis or narcolepsy, especially if the patient is experiencing excessive daytime sleepiness or other sleep-related symptoms.

Stroke or Transient Ischemic Attack (TIA): Despite the normal CT angiogram and lack of evident stenosis, dissection, or aneurysm, it's crucial not to miss a stroke or TIA, as these can have atypical presentations. The patient's hypertension and diabetes increase his risk for cerebrovascular disease.
Cardiac Arrhythmias: Although the ECG showed normal sinus rhythm and troponin was negative, cardiac arrhythmias can cause episodes of loss of consciousness or near-loss of consciousness. Further cardiac evaluation might be necessary to rule out arrhythmias, especially given the patient's history of hypertension and diabetes.

Cataplexy: A rare condition characterized by sudden, brief episodes of muscle weakness often triggered by strong emotions, which could be considered given the patient's description of being unable to move or speak during episodes.
Hyperekplexia: A rare genetic disorder that affects the brain's startle response, leading to stiffness and an inability to move in response to sudden stimuli, which might be a consideration in this case, although it is less likely given the patient's age and presentation.