Vitamin B12 deficiency results in the occurrence of systemic diseases in our nervous system. One of the most common manifestations of Vitamin B12 deficiency is subacute combined degeneration (SCD), which is characterized by paralysis and sensory changes of limbs, and disturbance of gait and position sense. SCD can be caused by the abuse of Happy Balloon, which comprises nitrous oxide and is used as a party hallucinogen. Diagnosis of SCD is achieved by combining the clinical symptoms, laboratory study, electrophysiological study and imaging findings. However, neurological symptoms observed during laboratory examinations are insufficient to diagnose SCD without the characteristic magnetic resonance imaging (MRI) findings. This is due to ambiguity of the symptoms and delayed report time of laboratory results in the emergency department. The ‘Inverted V sign’, observed towards the rear of the cervical and thoracic spine in T2 emphasis MRI images, is the most prominent finding of SCD. In most cases, the T1 image shows the same signal strength as the surrounding tissue. In the current report, we present an SCD case with an enhanced T1 phase of the MRI.