Differential Diagnosis for Ascending Weakness in Left Lower Limb
Single most likely diagnosis
- Lumbar Radiculopathy: The patient's symptoms of ascending weakness, numbness, and pain in the left lower limb, along with the MRI findings of disc bulge and nerve root compression at L4-L5 and L5-S1, support this diagnosis. The symptoms and MRI findings are consistent with nerve root irritation or compression, which is a common cause of radiculopathy.
Other Likely diagnoses
- Lumbar Disc Herniation: Although the MRI report mentions a diffuse bulge and small postero-central disc protrusion, a herniated disc could still be causing the patient's symptoms, especially if the herniation is compressing or irritating the nerve roots.
- Peripheral Neuropathy: The patient's symptoms of numbness and pain in the left lower limb could be indicative of a peripheral neuropathy, such as a peroneal or sciatic neuropathy, although the ascending nature of the weakness and the MRI findings make this less likely.
- Lumbosacral Plexopathy: The patient's symptoms could be caused by a lesion or injury to the lumbosacral plexus, which could be due to various causes such as trauma, infection, or tumor.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Cauda Equina Syndrome: Although the MRI report does not suggest a large disc herniation or significant compression of the cauda equina, this diagnosis should be considered due to the patient's symptoms of ascending weakness, numbness, and pain in the left lower limb. Cauda equina syndrome is a medical emergency that requires prompt surgical intervention.
- Spinal Cord Infarction: This diagnosis should be considered, especially if the patient has a history of vascular disease or other risk factors for spinal cord infarction. Spinal cord infarction can present with acute onset of weakness, numbness, and pain in the lower limbs.
- Spinal Epidural Abscess: This diagnosis should be considered, especially if the patient has a history of infection or immunocompromised state. Spinal epidural abscess can present with acute onset of weakness, numbness, and pain in the lower limbs, and requires prompt surgical intervention.
Rare diagnoses
- Guillain-Barré Syndrome: This is an autoimmune disorder that can present with ascending weakness, numbness, and pain in the lower limbs. Although it is a rare diagnosis, it should be considered, especially if the patient has a history of recent infection or vaccination.
- Neurodegenerative Disorders: Such as amyotrophic lateral sclerosis (ALS) or multiple system atrophy (MSA), which can present with progressive weakness, numbness, and pain in the lower limbs. However, these diagnoses are rare and would require further evaluation and testing to confirm.