Are sensory disturbances in multiple sclerosis (MS) usually unilateral or bilateral?

Sensory Disturbances in Multiple Sclerosis: Typically Unilateral but Can Present Bilaterally

Sensory disturbances in multiple sclerosis (MS) are typically unilateral at presentation, but can present bilaterally in some cases, particularly in certain variants of the disease. 1

Patterns of Sensory Disturbances in MS

Typical Presentation

• Most commonly, sensory symptoms in MS present unilaterally or asymmetrically
• Classic sensorimotor form presents with distal paresthesias or sensory loss that starts in one area before potentially progressing to other regions 2
• Sensory symptoms often begin in the legs and may progress to arms and cranial muscles 1
• Symptoms frequently follow a pattern reflecting the location of demyelinating lesions in the central nervous system

Atypical Presentations

• While always bilateral to some degree, sensory signs can be:
  • Asymmetrical
  • Predominantly proximal or distal
  • Start in the legs, arms, or simultaneously in all limbs 2
  • Present as severe and diffuse pain that precedes weakness 1

Clinical Variants and Special Considerations

MS Variants with Bilateral Sensory Involvement

• Pure sensory variant - can present with bilateral sensory symptoms without motor involvement 2
• Pure sensory ataxia - overlaps with Miller Fisher syndrome and may present with bilateral symptoms 2
• Bilateral sensory symptoms are more common in certain MS subtypes and clinical presentations

Diagnostic Red Flags

• Sudden onset of bilateral sensory loss should prompt consideration of alternative diagnoses 2
• Bilateral simultaneous sensory disturbances are less common in MS and may suggest other conditions
• Isolated cranial nerve involvement is rare in MS patients (10.4%), and isolated eighth nerve palsy is extremely rare (<1%) 2

Clinical Assessment of Sensory Disturbances

Evaluation Approach

• Clinical evaluation of sensory symptoms should be complemented by quantitative sensory tests for more objective assessment 3
• Somatosensory evoked potentials (SEPs) can detect subclinical sensory abnormalities 3
• MRI typically shows T2-hyperintense lesions that are periventricular, juxtacortical, or infratentorial 1

Important Clinical Correlations

• Sensory symptoms in MS correlate with the location of demyelinating lesions in the brain, spinal cord, and optic nerves 1
• Patients with lesions affecting the spinothalamo-cortical pathways are at higher risk of developing central pain 4
• Clinical evaluation of thermal sense may yield false negative findings (35%) compared to quantitative thermal threshold testing 3

Clinical Implications and Management

Diagnostic Considerations

• The McDonald criteria require evidence of dissemination in space (damage in different parts of the nervous system) and dissemination in time (damage occurring at different times) 1
• Early recognition of MS symptoms is crucial, as prompt diagnosis and treatment can potentially slow disease progression 1

Treatment Approach

• Disease-modifying therapies can reduce relapse rates by 29-68% compared to placebo or active comparators 1
• Management should address both the underlying disease process and symptomatic relief of sensory disturbances

Pitfalls and Caveats

• Bilateral simultaneous sensory symptoms should raise suspicion for alternative diagnoses, especially when they occur suddenly 2
• Young children (<6 years) with MS may present with nonspecific features including poorly localized pain or unsteady gait, making diagnosis challenging 1
• Sensory disturbances may be underestimated by standard clinical examination; quantitative sensory testing provides more objective evaluation 3
• Always consider MS mimics such as neuromyelitis optica, acute disseminated encephalomyelitis, and small vessel disease through appropriate testing 1

In conclusion, while MS sensory disturbances are typically unilateral or asymmetric at onset, bilateral presentations can occur and should be evaluated in the context of the overall clinical picture and supporting diagnostic studies.