**Question:** A 46-year-old male, Ashwath, presents to your OPD and while providing his history suddenly becomes incoherent and accuses you of stealing his thoughts. What is the diagnosis?

**Core Concept:** Transient global amnesia (TGA) is a temporary neurological disorder characterized by episodes of memory loss and disorientation, without focal neurological deficits or psychiatric symptoms.

**Why the Correct Answer is Right:** In TGA, the patient experiences a sudden onset of memory loss, anterograde (new information) and retrograde (past memories) amnesia, and disorientation. The episodes usually last less than 24 hours and resolve without neurological deficits. This clinical scenario fits the description of TGA, as it involves a sudden loss of memory and confusion without any evident neurological or psychiatric cause.

**Why Each Wrong Option is Incorrect:**

A. **Lambert-Eaton Myasthenic Syndrome (LEMS):** LEMS is a rare autoimmune disorder affecting the neuromuscular junction. The symptoms include muscle weakness, fatigue, and autonomic dysfunction, not memory loss and confusion.

B. **Cerebral Infarction (Stroke):** A stroke typically presents with focal neurological deficits, such as hemiparesis or aphasia, not the diffuse memory and confusion seen in TGA.

C. **Schizophrenia:** Schizophrenia is a psychiatric disorder characterized by delusions, hallucinations, and disorganized thinking, not the transient memory loss and confusion seen in TGA.

D. **Cognitive Impairment:** While cognitive impairment can be a sign, the sudden onset, memory loss, and confusion in TGA are distinct from the gradual decline in cognitive impairment.

**Clinical Pearl:** Transient global amnesia (TGA) is often misdiagnosed as psychiatric disorders due to its atypical presentation. It is essential to differentiate TGA from other conditions, as these entities have different treatment approaches and prognoses.

In conclusion, the correct answer is TGA because it presents with sudden memory loss, confusion, and resolves without any permanent neurological or psychiatric sequelae. The other options (LEMS, stroke, schizophrenia, and cognitive impairment) are distinct from TGA, with different clinical features, mechanisms, and treatment approaches. Always consider TGA when encountering a patient with sudden memory loss and confusion, as misdiagnosis can lead to unnecessary investigations and treatments.