Q) How do I assess for and treat neuropathic pain in MS?
In multiple sclerosis (MS), pain is a common symptom; patients may experience varying forms during their disease course. One type is neuropathic pain, which is initiated or caused by a demyelinating lesion in the central nervous system.1 It may occur spontaneously or be evoked, and it can be intermittent or steady. Given the nature of the disease course in MS, it is important to complete a pain assessment at each visit.
A patient experiencing neuropathic pain is likely to report abnormal sensations or hypersensitivity in the affected area. It is often combined with or adjacent to areas of sensory deficit.1 This includes altered sensations such as pins and needles, numbness, crawling, or burning. The most common MS-related neuropathic pain conditions are ongoing dysaesthetic extremity pain and paroxysmal pain, such as trigeminal neuralgia and Lhermitte phenomenon.1-3
Assessment. When assessing the history of neuropathic pain, it is beneficial to remember that abnormal sensory findings should be neuroanatomically aligned with a lesion site. The mnemonic OPQRST is a helpful reminder to ask about
Onset
Provoking/palliating factors
Quality of the sensation
If it radiates
Severity of the pain (using a scale of 0-10 can be helpful)
Time when the pain occurs.
These probing questions will aid diagnosis and uncover clues on areas to pay special attention to during the examination. For example, when a patient reports numbness of both feet, the clinician might suspect a lesion in the spinal cord and then can try to determine the level during the sensory exam.
Screening tools that capture the patient experience, such as the modified version of the Brief Pain Inventory (BPI), can assist in diagnosis as well as measure the impact of treatment.4
A physical assessment for neuropathic pain includes a full neurologic evaluation of motor, sensory, and autonomic systems to identify all signs of neurologic dysfunction. Attention should be paid to the possible types of negative sensory symptoms (eg, sensory loss) and positive findings (eg, paresthesia). When completing the sensory exam, the clinician can gauge pain by using a sharp object such as a toothpick. Tactile sense can be assessed with a piece of cotton, and temperature can be tested with warm and cold objects. A tuning fork can identify vibration sense. Body sensory maps, on which the clinician draws the sensory disturbance on schematic charts, can provide valuable information.
Diagnostic tests, such as MRI, can also assist in confirming the lesion of the somatosensory nervous system that explains the pain.
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