What are the causes and treatment options for C1-2 cord signal changes on imaging?

C1-2 Cord Signal Changes: Causes and Management

Primary Diagnostic Approach

MRI with and without IV contrast is the definitive imaging modality for evaluating C1-2 cord signal changes, as it provides superior soft-tissue resolution and multiplanar capability essential for identifying both compressive and non-compressive etiologies. 1

Compressive Etiologies

Degenerative and Structural Causes

• Spondylotic myelopathy is the most common cause of extrinsic cord compression in the cervical spine, resulting from degenerative changes, disc herniations, epidural lipomatosis, and malalignment 1
• Congenitally short pedicles can accentuate compression at the C1-2 level 1
• Hirayama disease (cervical flexion myelopathy), dorsal arachnoid webs, and ventral cord herniation represent rare structural causes requiring CT myelography or flexion/extension MRI for definitive diagnosis 1

Post-Surgical and Traumatic

• Early postoperative complications include hematomas, seromas, pseudomeningoceles, and epidural abscesses, all requiring MRI with contrast 1
• Late surgical complications such as adjacent level degenerative disease and recurrent disc herniation necessitate contrast-enhanced MRI 1
• Traumatic cord injury at C1-2 typically manifests with complete tetraplegia and loss of diaphragmatic control, given the critical neural pathways at this level 2

Neoplastic

• Primary and metastatic tumors of the extradural and intradural extramedullary spaces can compress the cord at C1-2, requiring contrast-enhanced MRI for evaluation 1
• Intramedullary tumors are rare causes but must be distinguished from syrinx using contrast enhancement 1

Non-Compressive Etiologies

Demyelinating Diseases

• Multiple sclerosis affects the cervical cord in 80-90% of cases and is characterized by lesions disseminated in space and time, fulfilling the 2016 MAGNIMS criteria 1
• Primary progressive MS demonstrates more extensive spinal cord involvement than relapsing-remitting MS 1
• Neuromyelitis optica (NMO) presents with longitudinally extensive cord lesions and optic neuritis, with brain lesions predominantly around the third and fourth ventricles 1
• Acute disseminated encephalomyelitis (ADEM) involves the spinal cord in approximately 25% of cases 1
• Contrast-enhanced imaging is recommended for initial diagnostic evaluation of all demyelinating conditions 1

Vascular Causes

• Spinal cord ischemia results from atheromatous disease, aortic surgery complications, thoracoabdominal aneurysms, systemic hypotension, or sickle cell disease 1
• Diffusion-weighted imaging should be included whenever spinal cord ischemia is suspected, as it demonstrates signal changes earlier than T2-weighted sequences 1
• Contrast enhancement is typically absent in early acute ischemia; if present, it suggests inflammatory or infectious etiology 1
• Spinal dural arteriovenous malformations/fistulas cause chronic progressive myelopathy through venous hypertension and cord edema, demonstrating patchy intramedullary enhancement and enlarged dorsal veins on contrast-enhanced MRI 1
• Hematomyelia from intramedullary AVM or spinal artery aneurysm rupture presents acutely 1

Metabolic and Toxic

• Subacute combined degeneration from vitamin B12 (cobalamin) deficiency, copper deficiency, or nitrous oxide inhalation produces characteristic MRI changes 1
• These metabolic causes are best evaluated with MRI and can mimic chronic infections 1

Infectious

• Chronic infections including human T cell lymphotropic virus myelitis, tuberculosis, schistosomiasis, HIV vacuolar myelopathy, and tertiary syphilis produce cord signal changes similar to metabolic causes 1
• MRI provides optimal visualization of both the osseous spinal column and spinal cord for infectious etiologies 1

Autoimmune and Inflammatory

• Systemic inflammatory conditions including systemic lupus erythematosus, Sjögren syndrome, mixed connective tissue disorder, Behçet disease, and sarcoidosis can cause myelopathy 1
• Paraneoplastic myelopathy requires MRI with contrast for evaluation 1

Radiation-Induced

• Radiation-induced myelopathy is a rare dose-dependent complication that anatomically localizes to a prior radiation port 1

Prognostic Significance of Signal Changes

T2 Hyperintensity

• Intramedullary T2 hyperintensity represents myelomalacia and gliosis, serving as a prognostic factor for neurosurgical outcome 1, 3
• The frequency of T2 hyperintensity is directly proportional to the severity of clinical myelopathy and degree of spinal canal compression 3
• Patients with T2 hyperintensity respond less favorably to surgical or medical treatment than those without 3
• Multisegmental T2 signal changes predict significantly poorer functional recovery rates compared to focal changes or no signal abnormality 4
• More than 60% of patients demonstrate T2 hyperintensity when myelopathy grade or canal compression is moderate to marked 3

T1 Hypointensity

• T1 hypointensity indicates severe spinal cord damage and correlates with lower preoperative and postoperative JOA scores and improvement rates 5
• Both T2 hyperintensity and T1 hypointensity warrant earlier surgical intervention before further cord damage occurs 5

Signal Resolution

• T2 hyperintensity can disappear after decompressive surgery and medical treatment in some cases, with three of four surgical patients showing good clinical improvement 3
• Serial MRI at 3 months post-surgery shows partial resolution in most cases, with complete resolution by 9 months in some patients 6

Treatment Algorithm

Compressive Lesions

• For spondylotic myelopathy with T2 signal changes, surgical decompression should be performed before the advent of intramedullary signal intensity changes to optimize outcomes 5
• Anterior decompression and fusion is more effective than posterior laminectomy for treating cervical myelopathy with intramedullary signal changes 5
• Characteristic enhancement patterns immediately at and below the stenosis level can be seen, though IV contrast is typically not required for diagnosis 1

Non-Compressive Lesions

• Demyelinating diseases require contrast-enhanced MRI for initial diagnostic evaluation 1
• Vascular malformations necessitate MRI with contrast to demonstrate cord edema and enlarged veins, potentially followed by spinal arteriography for intervention 1
• Metabolic causes require identification and correction of the underlying deficiency 1

Critical Clinical Correlation

Expected Findings at C1-2

• C1-2 cord pathology should produce bilateral upper extremity weakness affecting multiple myotomes (biceps, triceps, wrist extensors, finger flexors), not isolated single finger drop 2, 7
• Gait disturbance, lower extremity involvement, hyperreflexia, and sensory level changes are expected with significant C1-2 cord signal abnormality 2, 7
• Comprehensive neurological examination must systematically test all upper extremity myotomes, reflexes, gait, lower extremity function, and sensory distribution to accurately correlate imaging findings with clinical myelopathy 7

Pitfalls to Avoid

• Isolated peripheral findings (e.g., single finger drop) suggest radiculopathy at a different level (C6/C7) or peripheral nerve pathology rather than C1-2 cord pathology 7
• MRI findings of cord edema must correlate with clinical myelopathy to avoid false-positive findings in asymptomatic individuals 7
• In central cord syndrome patients, those with T2 hyperintensity have more severe initial neurological deficits but minimal early deterioration, while those without signal changes have less severe initial injury but expect slight decline in the first week 8