Differential Diagnosis for Numbness in the Medial Portion of the Sole of Both Feet
Single Most Likely Diagnosis
- Diabetic Neuropathy: Given the patient's pre-diabetic status, early signs of diabetic neuropathy could be presenting, even with normal vitamin B12 levels. Diabetic neuropathy often affects the distal extremities and can cause numbness in the feet.
Other Likely Diagnoses
- Tarsal Tunnel Syndrome: This condition involves compression of the posterior tibial nerve as it travels through the tarsal tunnel on the inner side of the ankle, which can cause numbness on the medial aspect of the foot.
- Peripheral Neuropathy: Other forms of peripheral neuropathy, not necessarily related to diabetes, could be causing the symptoms. This is a broad category and could be due to various underlying causes.
- Morton's Neuroma: Although more commonly associated with pain between the toes, in some cases, it can cause numbness, especially if it affects the nerves supplying the medial portion of the foot.
Do Not Miss Diagnoses
- Spinal Stenosis or Lumbar Radiculopathy: While less common, spinal issues such as lumbar radiculopathy or spinal stenosis can cause numbness in the feet. Missing these diagnoses could lead to significant morbidity if not addressed.
- Vitamin Deficiencies Other Than B12: Deficiencies in vitamins like B6 or B1 (thiamine) can also cause neuropathy. Although B12 levels are normal, other vitamin deficiencies should be considered.
Rare Diagnoses
- Amyloidosis: A rare condition characterized by the deposition of amyloid proteins in various tissues, including nerves, leading to neuropathy.
- Charcot-Marie-Tooth Disease: A group of inherited disorders that affect the peripheral nerves, leading to numbness and weakness in the feet and legs.
- Sarcoidosis: A condition that can cause neuropathy among its many manifestations, though it would be an uncommon cause of isolated foot numbness.
- Heavy Metal Poisoning: Exposure to heavy metals like lead or mercury can cause peripheral neuropathy, though this would be an unusual presentation without a known exposure history.