title: Primary somatosensory/motor cortical thickness distinguishes paresthesia-dominant from pain-dominant carpal tunnel syndrome.
abstract: Paresthesia-dominant and pain-dominant subgroups have been noted in carpal tunnel syndrome (CTS), a peripheral neuropathic disorder characterized by altered primary somatosensory/motor (S1/M1) physiology. We aimed to investigate whether brain morphometry dissociates these subgroups. Subjects with CTS were evaluated with nerve conduction studies, whereas symptom severity ratings were used to allocate subjects into paresthesia-dominant (CTS-paresthesia), pain-dominant (CTS-pain), and pain/paresthesia nondominant (not included in further analysis) subgroups. Structural brain magnetic resonance imaging data were acquired at 3T using a multiecho MPRAGE T1-weighted pulse sequence, and gray matter cortical thickness was calculated across the entire brain using validated, automated methods. CTS-paresthesia subjects demonstrated reduced median sensory nerve conduction velocity (P = 0.05) compared with CTS-pain subjects. In addition, cortical thickness in precentral and postcentral gyri (S1/M1 hand area) contralateral to the more affected hand was significantly reduced in CTS-paresthesia subgroup compared with CTS-pain subgroup. Moreover, in CTS-paresthesia subjects, precentral cortical thickness was negatively correlated with paresthesia severity (r(34) = -0.40, P = 0.016) and positively correlated with median nerve sensory velocity (r(36) = 0.51, P = 0.001), but not with pain severity. Conversely, in CTS-pain subjects, contralesional S1 (r(9) = 0.62, P = 0.042) and M1 (r(9) = 0.61, P = 0.046) cortical thickness were correlated with pain severity, but not median nerve velocity or paresthesia severity. This double dissociation in somatotopically specific S1/M1 areas suggests a neuroanatomical substrate for symptom-based CTS subgroups. Such fine-grained subgrouping of CTS may lead to improved personalized therapeutic approaches, based on superior characterization of the linkage between peripheral and central neuroplasticity.
authors.affiliation: Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA Department of Radiology, Logan University, Chesterfield, MO, USA Korean Institute of Oriental Medicine, Daejeon, Korea Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Medford, MA, USA Department of Physical Medicine and Rehabilitation, Harvard Medical School, Spaulding Rehabilitation Hospital, Boston, MA, USA Department of Pain Medicine, Harvard Vanguard Medical Associates, Atrium Health, Boston, MA, USA.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Maeda
authors.forename: Norman
authors.initials: N
authors.lastname: Kettner
authors.forename: Jieun
authors.initials: J
authors.lastname: Kim
authors.forename: Hyungjun
authors.initials: H
authors.lastname: Kim
authors.forename: Stephen
authors.initials: S
authors.lastname: Cina
authors.forename: Cristina
authors.initials: C
authors.lastname: Malatesta
authors.forename: Jessica
authors.initials: J
authors.lastname: Gerber
authors.forename: Claire
authors.initials: C
authors.lastname: McManus
authors.forename: Alexandra
authors.initials: A
authors.lastname: Libby
authors.forename: Pia
authors.initials: P
authors.lastname: Mezzacappa
authors.forename: Ishtiaq
authors.initials: I
authors.lastname: Mawla
authors.forename: Leslie R
authors.initials: LR
authors.lastname: Morse
authors.forename: Joseph
authors.initials: J
authors.lastname: Audette
authors.forename: Vitaly
authors.initials: V
authors.lastname: Napadow
mesh_terms: D000328:Adult; D002349:Carpal Tunnel Syndrome / Q000150:complications* / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000000981:diagnostic imaging / Q000473:pathology*; D010146:Pain / Q000209:etiology*; D010292:Paresthesia / Q000000981:diagnostic imaging*; D013003:Somatosensory Cortex / Q000473:pathology*