In a patient with multiple sclerosis (MS) presenting with paresthesias in all four limbs, where is the likely location of the lesion?

Lesion Location in Multiple Sclerosis with All Four Limbs Paresthesias

In a patient with multiple sclerosis presenting with paresthesias in all four limbs, the lesion is most likely located in the dorsal columns of the cervical spinal cord.

Anatomical Basis for Four-Limb Paresthesias in MS

• The dorsal columns of the spinal cord primarily transmit proprioception, vibration sensation, and fine touch information from the periphery to the brain 1
• Lesions affecting the cervical spinal cord, particularly the dorsal columns, can cause paresthesias in all four limbs due to the anatomical organization of sensory pathways 2
• MS lesions in the spinal cord are often small (at least 3mm), covering less than two vertebral segments and usually less than half of the cord area 2

Characteristic MS Spinal Cord Lesion Features

• On axial MRI images, most MS spinal cord lesions are located in the periphery of the spinal cord, mainly in the lateral or dorsal columns 2
• MS lesions can affect both the anterior white matter and the central gray matter, but focal lesions strictly confined to the gray matter are unusual in MS 2
• Typical MS spinal cord lesions are:
  • Focal with clearly demarcated borders 2
  • Cigar-shaped on sagittal images 2
  • Wedge-shaped on axial images 2

Evidence Supporting Cervical Cord Involvement

• The cervical portion of the spinal cord is more frequently involved in MS compared to thoracic or lumbar segments 2, 3
• Research has demonstrated that dorsal column signal abnormalities specifically correlate with sensory dysfunction (R = 0.58, P < 0.001) 4
• A study of MS lesion distribution found that 54.81% of spinal cord lesions were located in the cervical spinal cord, compared to 42.26% in the thoracic spinal cord 5

Clinical Correlation

• Pseudoathetosis (involuntary writhing movements when limbs are held outstretched) may accompany paresthesias when dorsal column lesions affect proprioception 6
• Lesions appearing in the lateral funiculi and central cord area significantly correlate with disability as measured by the Expanded Disability Status Scale (P < 0.001) 3
• Progressive MS subtypes tend to have more frequent involvement of the lateral funiculi compared to relapsing forms 3

Diagnostic Approach

• MRI of the cervical spine is essential for evaluating patients with suspected MS presenting with four-limb paresthesias 2
• Key MRI sequences should include T2-weighted and T1 post-gadolinium images of the brain and spinal cord 2
• Phase-sensitive inversion recovery (PSIR) sequences show higher sensitivity (77.10%) for cervical cord lesion detection compared to STIR (58.63%) and T2-weighted images (59.95%) 5
• Axial imaging is particularly important to accurately localize lesions within specific spinal cord columns 2

Differential Considerations

• Longitudinally extensive transverse myelitis (lesions extending over three or more vertebral segments) would suggest neuromyelitis optica spectrum disorder rather than MS 2
• Selective involvement of lateral and posterior columns may indicate subacute combined degeneration (B12/copper deficiency) rather than MS 2, 1
• Diffuse spinal cord lesions with ill-defined borders should not be considered as supporting a diagnosis of MS 2