Bilateral Tarsal Tunnel Syndrome

Abstract

I read the paper written by Morinaga and Shimizu,1Morinaga K. Shimizu T. Diagnosing bilateral tarsal tunnel syndrome.Am J Med. 2017; 130: e437-e438Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar entitled “Diagnosing Bilateral Tarsal Tunnel Syndrome,” that was published in October 2017. They reported an atypical presentation of a rare disease, bilateral tarsal tunnel syndrome, and emphasized the importance of avoiding the premature exclusion of this disease from the differential diagnosis when patients have bilateral symptoms. However, I have several concerns about the scientific validity of their comments. In their discussion, the authors cited a Japanese article2Kuniyasu R. Kim K. Isu T. Morimoto D. Kobayashi S. Morita A. Treatment of tarsal tunnel syndrome.Peripheral Nerve. 2014; 25 (in Japanese): 371Google Scholar reporting that 84%, not approximately 90%, of patients with tarsal tunnel syndrome had bilateral symptoms at the first office visit. However, the rate of bilateral tarsal tunnel syndrome in the cited article seems excessively high.2Kuniyasu R. Kim K. Isu T. Morimoto D. Kobayashi S. Morita A. Treatment of tarsal tunnel syndrome.Peripheral Nerve. 2014; 25 (in Japanese): 371Google Scholar, 3McSweeney S.C. Cichero M. Tarsal tunnel syndrome: a narrative literature review.Foot (Edinb). 2015; 25: 244-250Crossref PubMed Scopus (54) Google Scholar, 4Doneddu P.E. Coraci D. Loreti C. Piccinini G. Padua L. Tarsal tunnel syndrome: still more opinions than evidence. Status of the art.Neurol Sci. 2017; 38: 1735-1739Crossref PubMed Scopus (33) Google Scholar, 5Thomas P.K. Dyck P.J. Peripheral Neuropathy.4th ed. Elsevier, Philadelphia2005Google Scholar This study reported the characteristics of 83 cases of tarsal tunnel syndrome in a single center.2Kuniyasu R. Kim K. Isu T. Morimoto D. Kobayashi S. Morita A. Treatment of tarsal tunnel syndrome.Peripheral Nerve. 2014; 25 (in Japanese): 371Google Scholar However, it was not a full-length original article; rather, it was only an abstract. The reference standard of diagnosis was unclear, and clinically suspected (not definite) cases were also included. The types of examinations and tests performed are not described. Moreover, the authors of the cited article2Kuniyasu R. Kim K. Isu T. Morimoto D. Kobayashi S. Morita A. Treatment of tarsal tunnel syndrome.Peripheral Nerve. 2014; 25 (in Japanese): 371Google Scholar did not discuss why the rate of bilateral tarsal tunnel syndrome was extremely high. It is a universal consensus that symptoms of patients with tarsal tunnel syndrome are typically unilateral,3McSweeney S.C. Cichero M. Tarsal tunnel syndrome: a narrative literature review.Foot (Edinb). 2015; 25: 244-250Crossref PubMed Scopus (54) Google Scholar, 4Doneddu P.E. Coraci D. Loreti C. Piccinini G. Padua L. Tarsal tunnel syndrome: still more opinions than evidence. Status of the art.Neurol Sci. 2017; 38: 1735-1739Crossref PubMed Scopus (33) Google Scholar, 5Thomas P.K. Dyck P.J. Peripheral Neuropathy.4th ed. Elsevier, Philadelphia2005Google Scholar although the precise epidemiology of this disease is unclear.4Doneddu P.E. Coraci D. Loreti C. Piccinini G. Padua L. Tarsal tunnel syndrome: still more opinions than evidence. Status of the art.Neurol Sci. 2017; 38: 1735-1739Crossref PubMed Scopus (33) Google Scholar The discussion, which is based on research with poorly described methods, is scientifically misleading and can confuse the readers. Therefore, I suggest that the authors should remove this reference2Kuniyasu R. Kim K. Isu T. Morimoto D. Kobayashi S. Morita A. Treatment of tarsal tunnel syndrome.Peripheral Nerve. 2014; 25 (in Japanese): 371Google Scholar or mention its major limitations and uncommon findings. Finally, the name and number of authors in the reference cited in the paper written by Morinaga and Shimizu is incorrect.1Morinaga K. Shimizu T. Diagnosing bilateral tarsal tunnel syndrome.Am J Med. 2017; 130: e437-e438Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar, 2Kuniyasu R. Kim K. Isu T. Morimoto D. Kobayashi S. Morita A. Treatment of tarsal tunnel syndrome.Peripheral Nerve. 2014; 25 (in Japanese): 371Google Scholar Although underdiagnosis of tarsal tunnel syndrome is problematic, its overdiagnosis and misdiagnosis are also problematic.5Thomas P.K. Dyck P.J. Peripheral Neuropathy.4th ed. Elsevier, Philadelphia2005Google Scholar Given the absence of standard diagnostic criteria,4Doneddu P.E. Coraci D. Loreti C. Piccinini G. Padua L. Tarsal tunnel syndrome: still more opinions than evidence. Status of the art.Neurol Sci. 2017; 38: 1735-1739Crossref PubMed Scopus (33) Google Scholar, 6Patel A.T. Gaines K. Malamut R. Park T.A. Del Toro D.R. Holland N. Usefulness of electrodiagnostic techniques in the evaluation of suspected tarsal tunnel syndrome: an evidence-based review.Muscle Nerve. 2005; 32: 236-240Crossref PubMed Scopus (107) Google Scholar diagnosis of tarsal tunnel syndrome should be performed cautiously in patients with bilateral symptoms.