What is the most likely diagnosis for a 28-year-old woman presenting with a three-month history of numbness in the hands and feet, symmetrically brisk upper and lower extremity reflexes, mild weakness of ankle dorsiflexion, and spinal demyelination on Magnetic Resonance Imaging (MRI)?

Differential Diagnosis for a 28-year-old Woman with Numbness of Hands and Feet

Single most likely diagnosis

• Multiple Sclerosis (MS): The patient's symptoms of numbness in hands and feet, brisk reflexes, and down-going plantar responses, along with the MRI finding of spinal demyelination, are highly suggestive of MS. The disease often presents with a relapsing-remitting course, and the patient's age and symptoms are consistent with this diagnosis.

Other Likely diagnoses

• Subacute Combined Degeneration (Vitamin B12 Deficiency): This condition can cause demyelination in the spinal cord, leading to symptoms such as numbness, weakness, and impaired vibration sense. However, it typically also affects the dorsal columns, leading to impaired joint position sense, which is not present in this case.
• Chronic Inflammatory Demyelinating Polyneuropathy (CIDP): CIDP can cause symmetric weakness and sensory loss, but it typically does not cause spinal demyelination on MRI. The patient's symptoms and MRI findings make this diagnosis less likely.

Do Not Miss diagnoses

• Spinal Cord Compression: Although the MRI shows demyelination, it is essential to rule out spinal cord compression, which can cause similar symptoms. Compression can be due to various causes, such as a tumor or herniated disk, and requires urgent attention.
• Infectious or Inflammatory Myelitis: Conditions like transverse myelitis or infectious myelitis (e.g., due to Lyme disease or syphilis) can cause spinal cord inflammation and demyelination. These conditions can have a rapid onset and may require prompt treatment.

Rare diagnoses

• Leukodystrophies: These are a group of rare, inherited disorders that affect the growth or maintenance of the myelin sheath. They can cause progressive neurological symptoms, including numbness and weakness.
• Adrenoleukodystrophy: This is a rare, X-linked disorder that affects the myelin sheath and can cause spinal cord demyelination. It typically presents with adrenal insufficiency and neurological symptoms.
• Neuromyelitis Optica Spectrum Disorder (NMOSD): This is an autoimmune disorder that primarily affects the optic nerve and spinal cord, causing demyelination. It can present with symptoms similar to MS, but typically has a more severe course and requires distinct treatment.