From the Guidelines
Cranial nerves are typically not affected in myelopathy because myelopathy refers specifically to damage or dysfunction of the spinal cord, not the brain or brainstem where cranial nerves originate. Myelopathy causes symptoms related to spinal cord compression or injury, such as weakness, numbness, or tingling in the extremities, difficulty with coordination, gait disturbances, and bowel or bladder dysfunction. The twelve cranial nerves emerge directly from the brain and brainstem, bypassing the spinal cord entirely, so they remain functionally intact in pure myelopathy cases 1.
However, if a patient presents with both myelopathy and cranial nerve symptoms, clinicians should suspect a more extensive neurological condition affecting both the spinal cord and brain, such as multiple sclerosis, neurosarcoidosis, or a space-occupying lesion affecting multiple levels of the central nervous system 1. This distinction is important for accurate diagnosis and appropriate treatment planning, as management strategies differ significantly between isolated myelopathy and conditions affecting both spinal cord and cranial structures.
Some key points to consider in the evaluation of myelopathy include:
- The use of MRI to evaluate the spinal cord and surrounding structures 1
- The importance of considering inflammatory and infectious etiologies, such as multiple sclerosis and neuromyelitis optica 1
- The role of diffusion-weighted imaging in evaluating spinal cord ischemia 1
- The need to exclude alternative etiologies, such as trauma or space-occupying lesions, in the evaluation of myelopathy 1
In terms of specific cranial nerves, none are typically affected in pure myelopathy cases, as the condition is limited to the spinal cord and does not involve the brain or brainstem 1. However, if a patient presents with cranial nerve symptoms in addition to myelopathy, a more extensive neurological condition should be suspected, and further evaluation and treatment should be tailored accordingly 1.
From the Research
Cranial Nerves Affected in Myelopathy
The studies provided do not directly address the cranial nerves affected in myelopathy (spinal cord disease) 2, 3. However, other studies discuss cranial nerve involvement in various neurological conditions.
Cranial Neuropathies in Other Conditions
- Cranial nerve (CN) involvement is not a common feature of typical chronic inflammatory demyelinating polyneuropathy (CIDP), but patients with acute presentation of CN palsy in CIDP may be misdiagnosed and treated as other pathologies 4.
- Myelin-oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is an autoimmune-mediated demyelinating disease of the central nervous system (CNS) that may involve cranial nerves, with the trigeminal nerve being the most commonly affected nerve 5.
- Multiple myeloma (MM) can manifest as a solitary cerebral lesion, intra-parenchymal infiltration, or diffuse leptomeningeal disease, and can present with cranial nerve palsy, such as a sixth nerve palsy 6.
Specific Cranial Nerves Affected
- CN III, VII, X, XII were involved in a patient with CIDP 4.
- The trigeminal nerve is the most commonly affected nerve in MOGAD 5.
- The sixth nerve was affected in a patient with multiple myeloma 6.
There are no research papers provided that directly address the cranial nerves affected in myelopathy (spinal cord disease) 2, 3.