Multiple Sclerosis (MS): This is a common cause of spinal cord lesions, particularly in the cervical region. The presence of hyperintensity on STIR and T2-weighted images is consistent with demyelination, a hallmark of MS. The intermedullary location is also typical for MS plaques.

Spinal Cord Infarction: Although less common, spinal cord infarcts can present with hyperintensity on STIR and T2 images due to edema and necrosis. The clinical context, such as acute onset of symptoms, would support this diagnosis.
Spinal Cord Tumor (e.g., Astrocytoma, Ependymoma): These tumors can cause expansion of the spinal cord and signal changes on MRI, including T2 hyperintensity. They are less common than MS but should be considered, especially if there's a mass effect or if the lesion has a more solid appearance.
Transverse Myelitis: An inflammatory condition that can cause T2 hyperintensity across a segment of the spinal cord. It can be idiopathic or associated with various conditions, including infections, autoimmune diseases, or post-vaccination.

Spinal Dural Arteriovenous Fistula (SDAVF): Although rare, SDAVF can cause progressive myelopathy due to venous congestion. It's crucial to identify and treat this condition to prevent irreversible damage. MRI findings might be subtle, but the clinical presentation of progressive neurological deficit warrants consideration.
Infectious Myelitis (e.g., due to HIV, TB, or fungal infections): Infections can cause T2 hyperintensity in the spinal cord. Identifying an infectious cause is critical due to the potential for specific treatments that can significantly alter the outcome.
Spinal Cord Abscess: A serious condition that requires prompt diagnosis and treatment. While less common, the presence of fever, back pain, and neurological deficits should raise suspicion.

Neuromyelitis Optica (NMO): An autoimmune condition that predominantly affects the optic nerves and spinal cord. It can cause extensive lesions within the spinal cord, which appear as T2 hyperintensity on MRI.
Subacute Combined Degeneration (due to Vitamin B12 deficiency): This condition affects the dorsal and lateral columns of the spinal cord, leading to T2 hyperintensity. It's a rare cause of myelopathy but is important to recognize due to its treatable nature.
Leukodystrophies: A group of rare, genetic disorders that affect the growth or maintenance of the myelin sheath, leading to T2 hyperintensity in the spinal cord and brain. They typically present in childhood but some forms can have a later onset.