<p class="frontmatter-fieldnotes disclaimernew" style="margin-bottom:15px;">This work may not be copied, distributed, displayed, published, reproduced, transmitted, modified, posted, sold, licensed, or used for commercial purposes. By downloading this file, you are agreeing to the publisher’s <a href="/pages/termsofuse.aspx" target="_blank">Terms & Conditions</a>.</p>
<div id="x14l01632">
<div class="story">
<p class="ltrs-br-ltr-br-title"><span class="bold">Gabapentin and Venlafaxine Reduce Pain in a Patient With Somatic Symptom Disorder</span></p>
<p class="ltrs-br-ltr-br-body-text"><span class="semibold">To the Editor:</span> Here, a case of abdominal pain of unknown origin is presented. A thorough gastrointestinal workup was negative. The patient was then referred to psychiatry for further workup and management, with the suspicion that he was suffering from somatic symptom disorder.</p>
<p class="ltrs-br-ltr-br-body-text"> </p>
<p class="ltrs-br-ltr-br-body-text"><span class="semibold-ital">Case report.</span> Mr A is a 58-year-old man with a psychiatric history significant for major depressive disorder, alcohol use disorder, cannabis use disorder, and cocaine use disorder, all in sustained, full remission. He presented to the psychiatry outpatient clinic with anxiety and worsening abdominal pain for a period of 3 months. Review of Mr A’s chart showed an extensive gastrointestinal workup that was negative for structural, infectious, and autoimmune processes. He had been treated with amitriptyline 10 mg at bedtime by a psychiatrist earlier in the month, which did not help the pain. This medication was switched to nortriptyline 25 mg at bedtime, which also did not help the pain. Mr A was desperate for relief and reported that the abdominal pain had remained constant since it began 3 months prior. He rated the pain on a scale of 1 to 10 as a 7 at the time of interview but said that the pain often reaches maximum intensity of a 10. He denied constipation or diarrhea associated with the pain.</p>
<p class="ltrs-br-ltr-br-body-text">Following careful review of Mr A’s chart, the most likely diagnosis was somatic symptom disorder, according to <span class="italic">DSM-5</span> criteria. His symptoms had been present for 3 months, which does not exclude the diagnosis of somatic symptom disorder; it only qualifies the diagnosis as atypical. It was decided to discontinue nortriptyline treatment and begin a combined treatment of gabapentin and venlafaxine. Gabapentin was titrated to 300 mg 3 times per day, and venlafaxine extended release was titrated to 150 mg per day. At a 2-week follow-up, he reported improvement in pain symptoms. On a scale of 1 to 10, Mr A said the pain had dropped from a 10 to a 6. Gabapentin was increased to 300 mg 4 times per day to control residual pain. At a 4-week follow-up, Mr A reported the pain to be a 5, with fluctuations up to 7. Mr A is still on the venlafaxine and gabapentin regimen and is being followed closely by psychiatry and primary care.</p>
<p class="ltrs-br-ltr-br-body-text"> </p>
<p class="ltrs-br-ltr-br-body-text">In an animal study, gabapentin inhibited visceral pain when the pain was induced by an inflammatory stimulus or by stress.<span class="htm-cite"><a href="#ref1">1</a></span> In another small study comparing the use of gabapentin to placebo in 40 patients with irritable bowel syndrome,<span class="htm-cite"><a href="#ref2">2</a></span> a barostat study was used to determine threshold pressures for bloating, discomfort, and pain. The group given gabapentin showed an increased threshold compared to the placebo group.<span class="htm-cite"> </span>In a case report, gabapentin 1,800 mg allowed for a remission in somatoform pain disorder in a 48-year-old woman with depression.<span class="htm-cite"><a href="#ref3">3</a></span></p>
<p class="ltrs-br-ltr-br-body-text">Venlafaxine was used in Mr A to control his depression, as well as to contribute to pain control. Venlafaxine has been shown in several studies to improve pain symptoms that are associated with depression<span class="htm-cite"><a href="#ref4">4</a></span> as well as peripheral neuropathy.<span class="htm-cite"><a href="#ref5">5</a></span></p>
<p class="ltrs-br-ltr-br-body-text">In any patient, the differential diagnosis and medical examination must be exhausted before considering a psychogenic cause to the patient’s illness. Mr A meets the criteria for somatic symptom disorder. Irritable bowel syndrome cannot be excluded and has considerable overlap with somatization disorder.<span class="htm-cite"><a href="#ref6">6</a></span> More research is required to develop treatment modalities for somatic symptom disorder, as well as to differentiate between somatic symptom disorders affecting the gastrointestinal tract and irritable bowel syndrome. Although Mr A is not pain free, the reduction of pain is promising.</p>
<p class="ltrs-br-ltr-br-references-head"><span class="smallcaps">References</span></p>
<p class="references-references-text-1-9"><a name="ref1"></a>1. Gale JD, Houghton LA. Alpha 2 delta (α2δ) ligands, gabapentin and gregabalin: what is the evidence for potential use of these ligands in irritable bowel syndrome. <span class="italic">Front Pharmacol</span>. 2011;2:28. <span class="pubmed-crossref"><a href="
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=21713059&dopt=Abstract">PubMed</a> <a href="
http://dx.doi.org/10.3389/fphar.2011.00028">doi:10.3389/fphar.2011.00028</a></span></p>
<p class="references-references-text-1-9"><a name="ref2"></a>2. Lee KJ, Kim JH, Cho SW. Gabapentin reduces rectal mechanosensitivity and increases rectal compliance in patients with diarrhoea-predominant irritable bowel syndrome. <span class="italic">Aliment Pharmacol Ther</span>. 2005;22(10):981–988. <span class="pubmed-crossref"><a href="
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=16268973&dopt=Abstract">PubMed</a> <a href="
http://dx.doi.org/10.1111/j.1365-2036.2005.02685.x">doi:10.1111/j.1365-2036.2005.02685.x</a></span></p>
<p class="references-references-text-1-9"><a name="ref3"></a>3. Maurer I, Volz HP, Sauer H. Gabapentin leads to remission of somatoform pain disorder with major depression. <span class="italic">Pharmacopsychiatry</span>. 1999;32(6):255–257. <span class="pubmed-crossref"><a href="
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10599936&dopt=Abstract">PubMed</a> <a href="
http://dx.doi.org/10.1055/s-1999-7958">doi:10.1055/s-1999-7958</a></span></p>
<p class="references-references-text-1-9"><a name="ref4"></a>4. Bradley RH, Barkin RL, Jerome J, et al. Efficacy of venlafaxine for the long term treatment of chronic pain with associated major depressive disorder. <span class="italic">Am J Ther</span>. 2003;10(5):318–323. <span class="pubmed-crossref"><a href="
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12975715&dopt=Abstract">PubMed</a> <a href="
http://dx.doi.org/10.1097/00045391-200309000-00003">doi:10.1097/00045391-200309000-00003</a></span></p>
<p class="references-references-text-1-9"><a name="ref5"></a>5. Sindrup SH, Bach FW, Madsen C, et al. Venlafaxine versus imipramine in painful polyneuropathy: a randomized, controlled trial. <span class="italic">Neurology</span>. 2003;60(8):1284–1289. <span class="pubmed-crossref"><a href="
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12707430&dopt=Abstract">PubMed</a> <a href="
http://dx.doi.org/10.1212/01.WNL.0000058749.49264.BD">doi:10.1212/01.WNL.0000058749.49264.BD</a></span></p>
<p class="references-references-text-1-9"><a name="ref6"></a>6. Miller AR, North CS, Clouse RE, et al. The association of irritable bowel syndrome and somatization disorder. <span class="italic">Ann Clin Psychiatry</span>. 2001;13(1):25–30. <span class="pubmed-crossref"><a href="
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11465682&dopt=Abstract">PubMed</a> <a href="
http://dx.doi.org/10.3109/10401230109147126">doi:10.3109/10401230109147126</a></span></p>
<p class="ltrs-br-ltr-br-author"><span class="bold">Shady S. Shebak, MD</span></p>
<p class="ltrs-br-ltr-br-author"><a href="
mailto:ssshebak@carilionclinic.org">
ssshebak@carilionclinic.org</a></p>
<p class="ltrs-br-ltr-br-endmatter-fieldnotes"><span class="semibold-ital">Author affiliation:</span> Carilion Clinic, Virginia Tech Carilion School of Medicine, Roanoke, Virginia<span class="semibold">.</span></p>
<p class="ltrs-br-ltr-br-endmatter-fieldnotes"><span class="semibold-ital">Potential conflicts of interest:</span> None reported.</p>
<p class="ltrs-br-ltr-br-endmatter-fieldnotes"><span class="semibold-ital">Funding/support: </span>None reported.</p>
<p class="ltrs-br-ltr-br-endmatter-fieldnotes"><span class="semibold-ital">Published online:</span> July 31, 2014.</p>
<p class="ltrs-br-ltr-br-copyright-doi"><span class="italic">Prim Care Companion CNS Disord 2014;16(4):</span><span class="doi">doi:10.4088/PCC.14l01632</span></p>
<p class="ltrs-br-ltr-br-copyright-doi"><span class="italic">© Copyright 2014 Physicians Postgraduate Press, Inc.</span></p>
</div>
</div>