On T2WI, there is symmetric bilateral high signal intensity within the dorsal columns of the upper thoracic spinal cord. This appearance has been described as the inverted “V” sign, and typical MR feature of subacute combined degeneration (SCD). Typical T2 high signal intensity lesions in SCD typically begin in the upper thoracic region and usually have no contrast enhancement. The pathological findings of SCD consist of patchy losses of myelin in the dorsal and lateral columns. It is mostly due to VitB12 deficiency. Nitrous oxide, more commonly known as laughing gas, interferes with VitB12 bioavailability, and its abuse can result in SCD. dewi88
