Causes of Posterolateral Spinal Cord Syndrome
The most common cause of posterolateral (dorsolateral) spinal cord syndrome is subacute combined degeneration from vitamin B12 deficiency, which characteristically produces demyelination of both the posterior and lateral columns of the spinal cord. 1, 2
Primary Etiologies
Nutritional/Metabolic Causes
- Vitamin B12 (cobalamin) deficiency is the classic cause of posterolateral column syndrome, producing subacute combined degeneration with demyelination extending from the medulla oblongata through the cervical and thoracic spine 1, 2
- This can occur even without anemia or macrocytosis, making it easily missed if clinicians rely solely on hematologic findings 1
- MRI demonstrates characteristic T2 hyperintense signal changes in the posterior and lateral columns, most prominently in the cervical and thoracic regions 1, 2
Demyelinating Disease
- Multiple sclerosis can produce posterolateral column lesions, particularly affecting the posterior columns at cervical levels (C1-C4 in 80% of cases) 3, 4
- MS lesions in the posterior columns are typically focal, wedge-shaped on axial images, and involve the lateral or dorsal columns peripherally 3
- These lesions are more common in females and often present as the first manifestation of MS in 85% of cases with posterior column syndrome 4
Traumatic Causes
- Blunt spinal trauma can produce isolated posterior cord syndrome, though this is rare and often underdiagnosed 5
- Cervical spine fractures (including teardrop and hangman fractures) may cause selective posterior column injury 5
- Delayed MRI (obtained 10 months post-injury) may better delineate the anatomical focus of posterior column damage 5
Congenital/Developmental Causes
- Tethered cord syndrome can produce posterolateral column dysfunction through chronic stretching and metabolic failure of the spinal cord 6
- Dysraphic malformations including myelomeningocele are associated with conus medullaris involvement 7
Vascular Causes
- Ischemic and hemorrhagic infarcts can selectively affect the posterolateral columns, though this is less common 7
Clinical Pitfalls
A critical diagnostic error is dismissing vitamin B12 deficiency because complete blood counts are normal - subacute combined degeneration can occur without anemia or macrocytosis, requiring direct measurement of serum cobalamin levels 1.
The posterior column syndrome in MS is often misdiagnosed because routine neurological examination may show only subtle deficits, yet patients experience severe functional impairment in activities of daily living, particularly with hand dexterity and proprioception 4, 8.
Diagnostic Approach
- Obtain serum vitamin B12 levels in all patients presenting with posterolateral column signs, regardless of hematologic parameters 1, 2
- Perform MRI of the entire spinal cord (cervical through thoracic) with T2-weighted sequences to identify characteristic hyperintense signal changes in posterior and lateral columns 1, 2
- Consider brain MRI and cerebrospinal fluid analysis when demyelinating disease is suspected 4
- In trauma cases, consider delayed MRI at 10 months if initial imaging is inconclusive, as this may better demonstrate the anatomical lesion 5