What is the typical pattern seen with Multiple Sclerosis (MS)?

Typical Patterns Seen in Multiple Sclerosis

Multiple sclerosis is characterized by four main clinical phenotypes: relapsing-remitting MS (RRMS), secondary progressive MS (SPMS), primary progressive MS (PPMS), and clinically isolated syndrome (CIS), with RRMS being the most common initial presentation pattern affecting approximately 85-90% of patients. 1

Clinical Course Patterns

• Relapsing-Remitting MS (RRMS): Characterized by clearly defined relapses with full or partial recovery, without disease progression between attacks, typically presenting in younger patients 1
• Secondary Progressive MS (SPMS): Follows an initial relapsing-remitting course with subsequent progressive deterioration for at least six months, with or without superimposed relapses 1, 2
• Primary Progressive MS (PPMS): Characterized by progressive deterioration from disease onset without relapses or remissions, affecting approximately 10-15% of MS patients 1, 2
• Clinically Isolated Syndrome (CIS): The first clinical episode with features suggestive of MS but not yet meeting full criteria for MS diagnosis 1

MRI Patterns and Lesion Characteristics

Typical Lesion Distribution

• Multiple round to ovoid T2-hyperintense lesions are found in characteristic locations, including periventricular, juxtacortical, infratentorial, and spinal cord regions 3
• Periventricular lesions are in direct contact with the lateral ventricles, without intervening white matter 3, 2
• Juxtacortical lesions abut the cortex without intervening normal white matter 3
• Infratentorial lesions appear in the brainstem, cerebellar peduncles, or cerebellum 3
• MS spinal cord lesions are often multiple and short in cranio-caudal diameter, with the cervical portion more frequently involved 3, 4

Lesion Enhancement Patterns

• The pattern of gadolinium enhancement in MS lesions is variable but almost always transient, indicating active inflammation and breakdown of the blood-brain barrier 3
• In RRMS and SPMS, approximately 80% of new lesions show gadolinium enhancement 2, 1
• In benign MS, only about 33% of new lesions enhance 2
• In PPMS, only about 5% of new lesions show gadolinium enhancement 2, 1

Diagnostic Imaging Recommendations

• T2-weighted spin echo sequences are more sensitive than T1-weighted ones for demonstrating MS lesions 2
• A moderately T2-weighted sequence is optimal for demonstrating periventricular lesions, while a heavily T2-weighted sequence is optimal for demonstrating cortical lesions 2
• Key MRI sequences should include T2-weighted and T1 post-gadolinium images of the brain and spinal cord 3
• Gadolinium enhancement should be used in monitoring treatment in MS 2
• Scanning should start at least five minutes after injection of Gd-DTPA, as most lesions display maximum enhancement five to 30 minutes post injection 2

Red Flags in Imaging

• Symmetric central pontine lesions suggest small-vessel disease rather than MS 3
• Periaqueductal lesions or area postrema lesions suggest neuromyelitis optica spectrum disorders 3
• Longitudinally extensive spinal cord lesions affecting more than three vertebral segments suggest neuromyelitis optica spectrum disorder rather than MS 3, 4

Disease Progression and Prognosis

• Only 5-10% of MS patients have the primary progressive course 2
• The remainder have an initial relapsing-remitting course, of whom around two-thirds subsequently develop secondary progression, while most of the remainder have a benign course 2
• The term "benign MS" should be used with caution as the disease course can worsen at any time 1
• For diagnosis of MS, there should be at least one typical MS lesion in at least two characteristic regions (periventricular, juxtacortical, infratentorial, and spinal cord) 3

Clinical Implications

• MRI monitoring is most useful in patients with early relapsing-remitting and secondary progressive MS, since they have the most asymptomatic disease activity 2
• Clinical assessments measuring disability and recording relapses should always be performed in parallel with MRI 2
• Serial imaging supports the diagnosis, as MS is characterized by the accrual of lesions over time and in new areas of the CNS 3

Understanding these typical patterns is crucial for early diagnosis, monitoring disease progression, and evaluating treatment response in patients with multiple sclerosis.