C o n t i n u i n g E d u c a t i o n A l b e r t aTable 1: Selected conditions associatedwith neuropathic pa<strong>in</strong>* 2,61,89Diabetic neuropathyPos<strong>the</strong>rpetic neuralgiaHIV <strong>in</strong>fectionTumour <strong>in</strong>vasionRadiationChemo<strong>the</strong>rapy-<strong>in</strong>duced nerve damagePost-surgical nerve traumaPhantom limb pa<strong>in</strong>Lumbar degenerative disc disease<strong>Chronic</strong> low back pa<strong>in</strong>Complex regional pa<strong>in</strong> syndromeTrigem<strong>in</strong>al neuralgiaVulvodyniaPost-stroke pa<strong>in</strong>Multiple sclerosisSp<strong>in</strong>al cord <strong>in</strong>jury*NB: patients may also have neuropathic pa<strong>in</strong>without a diagnosed conditionsk<strong>in</strong> (mechanical allodynia); burn<strong>in</strong>g when<strong>the</strong> sk<strong>in</strong> is touched by someth<strong>in</strong>g cold, oreven cool (<strong>the</strong>rmal allodynia); pa<strong>in</strong> thatlasts long after an <strong>in</strong>itiat<strong>in</strong>g event (hyperpathia);an exaggerated response to pa<strong>in</strong>fulstimuli, such as a p<strong>in</strong>-prick (hyperalgesia);a difficult to describe, unusual or unpleasant“numbness” (dyses<strong>the</strong>sia); and tendernesswhen <strong>the</strong> area is touched gently.Additional symptoms may <strong>in</strong>clude fullor partial loss <strong>of</strong> sensation <strong>in</strong> <strong>the</strong> area <strong>of</strong>pa<strong>in</strong> (presumably from <strong>the</strong> <strong>in</strong>itiat<strong>in</strong>g nervedamage), and pa<strong>in</strong> that radiates to adjacent areas (i.e., not welllocalized). Unlike certa<strong>in</strong> <strong>in</strong>flammatory conditions, neuropathicpa<strong>in</strong> also tends to be asymmetrical.Neuropathic pa<strong>in</strong> is classified as cont<strong>in</strong>uous, spontaneous orstimulus-evoked with “out <strong>of</strong> <strong>the</strong> blue” be<strong>in</strong>g a particularly tell<strong>in</strong>gdescription. O<strong>the</strong>r trigger words <strong>in</strong>clude cutt<strong>in</strong>g, prickl<strong>in</strong>g, throbb<strong>in</strong>gor crush<strong>in</strong>g, and shoot<strong>in</strong>g, stabb<strong>in</strong>g, lanc<strong>in</strong>at<strong>in</strong>g or jabb<strong>in</strong>g. 2,7-22So how does one sort this out? Obviously <strong>the</strong> first step is tohave <strong>the</strong> patient see a doctor for diagnosis. Figure 1 (“About MyPa<strong>in</strong>”) is an example <strong>of</strong> one tool that can facilitate communicationbetween <strong>the</strong> patient and his or her doctor about <strong>the</strong> possibility <strong>of</strong>neuropathic pa<strong>in</strong>. Designed for use through <strong>the</strong> pharmacist, it isbased on multiple validated pa<strong>in</strong> questionnaires developed by pa<strong>in</strong>specialists. 10-12,14-22 It is <strong>in</strong>tended to help patients del<strong>in</strong>eate <strong>the</strong>ir pa<strong>in</strong>symptoms and history before <strong>the</strong>y see <strong>the</strong> doctor, and <strong>in</strong> turn, helpsave physicians’ time while alert<strong>in</strong>g <strong>the</strong>m to <strong>the</strong> possibility <strong>of</strong> neuropathicpa<strong>in</strong>. For expediency, as well as ease <strong>of</strong> use, only selectedsymptoms are <strong>in</strong>cluded. S<strong>in</strong>ce <strong>the</strong>se rarely occur <strong>in</strong> o<strong>the</strong>r pa<strong>in</strong> conditions,<strong>the</strong> physician should be able to quickly identify potentialneuropathic pa<strong>in</strong>, and follow up with fur<strong>the</strong>r <strong>in</strong>vestigation.Two po<strong>in</strong>ts are worth not<strong>in</strong>g with respect to recogniz<strong>in</strong>g neuropathicpa<strong>in</strong>. <strong>The</strong> first is that it always <strong>in</strong>volves or requires morethan one word or characteristic. Secondly, <strong>the</strong> absence <strong>of</strong> an evenparticularly characteristic symptom does not necessarily preclude<strong>the</strong> presence <strong>of</strong> neuropathic pa<strong>in</strong>. 9Figure 1: About my pa<strong>in</strong><strong>The</strong> follow<strong>in</strong>g are some <strong>of</strong> <strong>the</strong> ways people describe pa<strong>in</strong> from damaged nerves.This k<strong>in</strong>d <strong>of</strong> pa<strong>in</strong> is usually treated differently than “ord<strong>in</strong>ary” or “normal” pa<strong>in</strong>.To help your doctor know <strong>the</strong> best way to treat your pa<strong>in</strong>, check as many spots as apply,and add any o<strong>the</strong>r words or symptoms that aren’t <strong>in</strong> <strong>the</strong> checklist.If you have pa<strong>in</strong> <strong>in</strong> more than one place, use a separate form for each area.My Pa<strong>in</strong> Is…oburn<strong>in</strong>golike an electric shockot<strong>in</strong>gl<strong>in</strong>g or prickl<strong>in</strong>gonumb (or just feels abnormal)otender even when pressed gentlyoradiat<strong>in</strong>g (mov<strong>in</strong>g from its orig<strong>in</strong>al spot)osensitive to light touch (such as a gentle breeze or loose cloth<strong>in</strong>g)O<strong>the</strong>r ways I describe my pa<strong>in</strong> are…__________________________________________________________________________________________________________________________________________Take this form to your doctor. <strong>The</strong> follow<strong>in</strong>g are some questions he or she may ask.Th<strong>in</strong>k about <strong>the</strong>se before you see your doctor so <strong>the</strong>y are easier to answer “on <strong>the</strong> spot.”• Exactly where is <strong>the</strong> pa<strong>in</strong>?• Is <strong>the</strong> pa<strong>in</strong> always <strong>the</strong>re, come and go, or seem to appear “out <strong>of</strong> <strong>the</strong> blue?”• How long have you had this pa<strong>in</strong>?• What makes <strong>the</strong> pa<strong>in</strong> worse?• What makes <strong>the</strong> pa<strong>in</strong> better?• What medication(s) have you tried, and how much have <strong>the</strong>y helped?• Besides medication, what else have you tried?Important: This form is not meant to diagnose any certa<strong>in</strong> type <strong>of</strong> pa<strong>in</strong>. Only yourdoctor is able to do this. If you or your doctor have any questions about this form, orabout pa<strong>in</strong> medications, please feel free to contact your pharmacist.Pharmacy Contact InformationCopyright Brenda McBean Cochran; April 2009Pharmacological management <strong>of</strong> chronicneuropathic pa<strong>in</strong><strong>Chronic</strong> neuropathic pa<strong>in</strong> has historically been treated <strong>the</strong> sameway as any chronic pa<strong>in</strong>—rang<strong>in</strong>g from simple analgesics to opiates.Grow<strong>in</strong>g recognition that neuropathic pa<strong>in</strong> has quite differentpathophysiology than nociceptive pa<strong>in</strong> prompted <strong>the</strong> CanadianPa<strong>in</strong> Society to develop a 2007 consensus statement and guidel<strong>in</strong>esfor <strong>the</strong> pharmacological management <strong>of</strong> chronic neuropathicpa<strong>in</strong> (hereafter referred to as <strong>the</strong> “Canadian Guidel<strong>in</strong>es”). 2 Us<strong>in</strong>gan evidence-based approach and recogniz<strong>in</strong>g that treatment mustbe <strong>in</strong>dividualized for each patient, tiered recommendations weremade for each class <strong>of</strong> medication used <strong>in</strong> chronic neuropathicpa<strong>in</strong>. (Figure 2)Brief overview <strong>of</strong> neuropathic pa<strong>in</strong> pathophysiologyAn appreciation <strong>of</strong> chronic neuropathic pa<strong>in</strong> pathophysiology (atleast as far as we know it) can help pharmacists understand <strong>the</strong>rationale for drug choices <strong>in</strong> this condition.Hyperactivity <strong>in</strong> both <strong>the</strong> central and peripheral nervous systemscontributes, through a variety <strong>of</strong> mechanisms, to neuropathicpa<strong>in</strong>. Briefly, damaged nerves become highly sensitive to mechanicalstimulation and may also beg<strong>in</strong> to generate impulses on <strong>the</strong>ir own(<strong>of</strong>ten referred to as “central” or “peripheral sensitization”). This <strong>in</strong>creasedsensitivity and spontaneous activity appears to be due to <strong>in</strong>creasedconcentration <strong>of</strong> sodium channels, as well as <strong>in</strong>creased sen-CE 2June 2009 | pharmacy practice