Erratum to “Carpal tunnel syndrome in Parkinson’s disease” [Eur. J. Radiol. 67 (3) (2008) 550]

Abstract

Yucel et al. recently reported the sonographic findings of the median nerve and prevalence of carpal tunnel syndrome in patients with Parkinson’s disease in the European Journal of Radiology, 2007 September 11 [Epub ahead of print]. It is an important contribution to the known data about Parkinson’s disease. As far as we know there is not much work on carpal tunnel syndrome in patients with Parkinson’s disease in the literature.The authors have indicated that tremor may be a risk factor for carpal tunnel syndrome because of repetitive trauma. Tremor is the most frequent symptom seen in Parkinson’s disease in approximately 80% of patients [[1]Clarke C.E. Parkinson’s disease.BMJ. 2007; 335: 441-445Crossref PubMed Scopus (70) Google Scholar]. Results regarding the correlation of carpal tunnel syndrome and the tremor status of the subjects would be an important evidence to support this hypothesis; however, this is not investigated in the paper. Furthermore, resting tremor that is seen mainly in Parkinson’s disease resembles pill rolling movement [[2]Samii A. Nutt J.G. Ransom B.R. Parkinson’s disease.The Lancet. 2004; 363: 1783-1793Abstract Full Text Full Text PDF PubMed Scopus (936) Google Scholar]. Flexion and extension of fingers together with adduction and abduction of the thumb give the classic ‘pill rolling’ tremor [[3]Anouti A. Koller W.C. Tremor disorders. Diagnosis and management.West J Med. 1995; 162: 510-513PubMed Google Scholar]. Tremor affects mainly finger joints rather than wrist joint in Parkinson’s disease; so the tremor in finger joints may be less likely to cause repetitive trauma in the carpal tunnel region.Other hypothesis that needs to be investigated may be rigidity and bradykinesia as confounding factors in the pathogenesis of median nerve entrapment in the carpal tunnel. Rigidity and bradykinesia are two cardinal motor symptoms in this movement disorder. However, no research has been conducted searching the relationship between rigidity–bradykinesia and carpal tunnel syndrome in Parkinson’s disease. Further studies on this subject may contribute valuable information.Many physiological factors affect different parameters in electrophysiological studies. It is well known that temperature variations lead to changes in amplitudes of nerve action potentials [[4]Dumitru D. Amato A.A. Zwarts M.J. Nerve conduction studies.in: Dumitru D. Amato A.A. Zwarts M.J. Electrodiagnostic medicine. second ed. Hanley and Belfus Inc., Philadelphia2002: 159-223Google Scholar]. In order to reduce this type of error, temperature of the patient and the laboratory room should be recorded and electrophysiological studies are to be conducted in standardized room and body temperatures in all study subjects. This is especially important the population of the present study, since patients with Parkinson’s disease could experience temperature dysregulation and excessive sweating [[5]Dubow J.S. Autonomic dysfunction in Parkinson’s disease.Dis Mon. 2007; 53: 265-274Abstract Full Text Full Text PDF PubMed Scopus (43) Google Scholar]. In Table 2, authors show that “the amplitude of median nerve in the second finger was significantly lower in patients with Parkinson’s disease (27.9 ± 13.7 mV) than control group (36.9 ± 17.9 mV), both being within normal limits (p = 0.010).” However, Table 3 demonstrates that these amplitudes are 25.3 ± 13.9 mV and 31.1 ± 12.9 mV in patients with mild and severe Parkinson’s disease, respectively. Lower amplitude values in patients with milder Parkinson’s disease are paradoxical and inconsistent with the authors’ postulation.It may be worth to examine the existence of carpal tunnel syndrome in Parkinson’s disease using standardized and well-designed techniques and to correlate the findings with the symptoms of the disease. Yucel et al. recently reported the sonographic findings of the median nerve and prevalence of carpal tunnel syndrome in patients with Parkinson’s disease in the European Journal of Radiology, 2007 September 11 [Epub ahead of print]. It is an important contribution to the known data about Parkinson’s disease. As far as we know there is not much work on carpal tunnel syndrome in patients with Parkinson’s disease in the literature. The authors have indicated that tremor may be a risk factor for carpal tunnel syndrome because of repetitive trauma. Tremor is the most frequent symptom seen in Parkinson’s disease in approximately 80% of patients [[1]Clarke C.E. Parkinson’s disease.BMJ. 2007; 335: 441-445Crossref PubMed Scopus (70) Google Scholar]. Results regarding the correlation of carpal tunnel syndrome and the tremor status of the subjects would be an important evidence to support this hypothesis; however, this is not investigated in the paper. Furthermore, resting tremor that is seen mainly in Parkinson’s disease resembles pill rolling movement [[2]Samii A. Nutt J.G. Ransom B.R. Parkinson’s disease.The Lancet. 2004; 363: 1783-1793Abstract Full Text Full Text PDF PubMed Scopus (936) Google Scholar]. Flexion and extension of fingers together with adduction and abduction of the thumb give the classic ‘pill rolling’ tremor [[3]Anouti A. Koller W.C. Tremor disorders. Diagnosis and management.West J Med. 1995; 162: 510-513PubMed Google Scholar]. Tremor affects mainly finger joints rather than wrist joint in Parkinson’s disease; so the tremor in finger joints may be less likely to cause repetitive trauma in the carpal tunnel region. Other hypothesis that needs to be investigated may be rigidity and bradykinesia as confounding factors in the pathogenesis of median nerve entrapment in the carpal tunnel. Rigidity and bradykinesia are two cardinal motor symptoms in this movement disorder. However, no research has been conducted searching the relationship between rigidity–bradykinesia and carpal tunnel syndrome in Parkinson’s disease. Further studies on this subject may contribute valuable information. Many physiological factors affect different parameters in electrophysiological studies. It is well known that temperature variations lead to changes in amplitudes of nerve action potentials [[4]Dumitru D. Amato A.A. Zwarts M.J. Nerve conduction studies.in: Dumitru D. Amato A.A. Zwarts M.J. Electrodiagnostic medicine. second ed. Hanley and Belfus Inc., Philadelphia2002: 159-223Google Scholar]. In order to reduce this type of error, temperature of the patient and the laboratory room should be recorded and electrophysiological studies are to be conducted in standardized room and body temperatures in all study subjects. This is especially important the population of the present study, since patients with Parkinson’s disease could experience temperature dysregulation and excessive sweating [[5]Dubow J.S. Autonomic dysfunction in Parkinson’s disease.Dis Mon. 2007; 53: 265-274Abstract Full Text Full Text PDF PubMed Scopus (43) Google Scholar]. In Table 2, authors show that “the amplitude of median nerve in the second finger was significantly lower in patients with Parkinson’s disease (27.9 ± 13.7 mV) than control group (36.9 ± 17.9 mV), both being within normal limits (p = 0.010).” However, Table 3 demonstrates that these amplitudes are 25.3 ± 13.9 mV and 31.1 ± 12.9 mV in patients with mild and severe Parkinson’s disease, respectively. Lower amplitude values in patients with milder Parkinson’s disease are paradoxical and inconsistent with the authors’ postulation. It may be worth to examine the existence of carpal tunnel syndrome in Parkinson’s disease using standardized and well-designed techniques and to correlate the findings with the symptoms of the disease. Carpal tunnel syndrome in Parkinson's diseaseEuropean Journal of RadiologyVol. 67Issue 3PreviewYucel et al. recently reported the sonographic findings of the median nerve and prevalence of carpal tunnel syndrome in patients with Parkinson's disease in the European Journal of Radiology, 2007 September 11 [Epub ahead of print]. It is an important contribution to the known data about Parkinson's disease. As far as we know there is not much work on carpal tunnel syndrome in patients with Parkinson's disease in the literature. Full-Text PDF