Multiple Sclerosis (MS): This is a chronic autoimmune disease that affects the central nervous system, leading to demyelination and a wide range of neurological symptoms, including numbness in the face and legs. The pattern of numbness, along with other symptoms such as vision problems, weakness, and balance issues, can suggest MS.

Stroke or Transient Ischemic Attack (TIA): Numbness in the face and leg on one side of the body can be a symptom of a stroke or TIA, which occurs when the blood supply to part of the brain is interrupted or reduced.
Peripheral Neuropathy: This condition results from damage to the peripheral nerves and can cause numbness, usually starting in the feet and hands, but can also affect the face and legs in some cases.
Trigeminal Neuralgia: Although primarily causing facial pain, in some cases, it can lead to numbness or altered sensation in the face.

Brain Tumor: A tumor in the brain can cause numbness in the face and leg by compressing or invading nearby brain tissue. Early detection is crucial for treatment and prognosis.
Spinal Cord Compression: Compression of the spinal cord can cause numbness, weakness, and loss of bladder and bowel control. It is a medical emergency requiring prompt intervention.
Lyme Disease: In its later stages, Lyme disease can cause neurological symptoms, including numbness and tingling in the face and extremities.

Sjögren's Syndrome: An autoimmune disorder that can cause numbness and tingling in the extremities, among other symptoms, due to peripheral neuropathy.
Vitamin B12 Deficiency: Can lead to neurological symptoms, including numbness and tingling in the hands and feet, and less commonly, the face.
Sarcoidosis: A condition where inflammatory cells form in different parts of the body, including the nervous system, leading to a variety of neurological symptoms, including numbness.