We investigated the thermographic findings of carpal tunnel syndrome (CTS). We enrolled 304 hands with electrodiagnostically identified CTS and 88 control hands. CTS hands were assigned to duration groups (D1, < 3 months; D2, 3‒6 months; D3, 6‒12 months; D4, ≥ 12 months) and severity groups (S1, very mild; S2, mild; S3, moderate; S4, severe). The temperature difference between the median and ulnar nerve territories (ΔM-U territories) decreased as CTS duration and severity increased. Significant differences in ΔM-U territories between the D1 and D3, D1 and D4, D2 and D4, and S1 and S4 groups (P = 0.003, 0.001, 0.001, and < 0.001, respectively) were observed. Thermal anisometry increased as CTS duration and severity increased. Significant differences in thermal anisometry between the D1 and D4 as well as the D2 and D4 groups (P = 0.005 and 0.04, respectively) were noted. Thermal anisometry was higher in the S4 group than in the S1, S2, and S3 groups (P = 0.009, < 0.001, and 0.003, respectively). As CTS progresses, skin temperature tends to decrease and thermal variation tends to increase in the median nerve-innervated area. Thermographic findings reflect the physiological changes of the entrapped median nerve.

Purpose: A bifid median nerve (BMN) is not a rare variant. This study aimed to investigate the features of carpal tunnel syndrome (CTS) accompanied by BMN. Patients and Methods: In this retrospective study, we defined a BMN group as CTS with BMN and a non-bifid median nerve (NMN) group as CTS without BMN. All hands were assigned to four severity grades according to the findings of electrodiagnosis (EDx): very mild, mild, moderate, and severe. The cross-sectional area (CSA) of the median nerve, palmar bowing of the flexor retinaculum, and persistent median artery (PMA) were assessed by ultrasonography. Numerical pain rating scale (NRS) and symptom duration were assessed as clinical variables. Results: Sixty-four hands (57 patients) and 442 hands (341 patients) were enrolled in the BMN and the NMN groups, respectively. BMN was prevalent in 12.6% of all CTS hands. The distribution of EDx severity grade was milder in the BMN group than in the NMN group (P<0.001). The CSA of the BMN group was 16.2±4.1 mm 2 , slightly larger than 15.1±4.2 mm 2 in the NMN group (P=0.056). The BMN group showed higher NRS than the NMN group (5.5±1.5 and 4.4±1.7, respectively; P<0.001). In the subgroup analysis, NRS was significantly higher in the BMN group than in the NMN group at all EDx severity grades. In the BMN group, the PMA group showed greater EDx severity (P=0.037) and higher NRS (6.0 and 5.0, respectively; P=0.012) than the non-PMA group. The radial side branch's CSA was larger than that of the ulnar side branch (10.0 mm 2 and 6.0 mm 2 , respectively; P<0.001). Conclusion: CTS with BMN presented more severe symptoms and relatively milder EDx severity. When assessing the severity of CTS with BMN, the clinical symptoms should primarily be considered, as well as we should complementarily evaluate the EDx and ultrasonography.

Rationale: Intraoperative neurophysiological monitoring (IONM) has been utilized not only for the rapid detection of neural insults during surgeries, but also to verify the neurophysiological integrity of nerve lesions in the surgical field. Patient concerns: A 32-year-old woman presented with a wrist and finger drop that had lasted about 3 months. Diagnoses: The result of the initial electrodiagnostic test was consistent with posterior interosseous nerve (PIN) syndrome. Ultrasonography and magnetic resonance imaging of the proximal forearm showed a cystic mass at the anterolateral aspect of the radial head, which was diagnosed as a ganglion cyst. Interventions: Surgical release of the ganglion cyst with IONM was performed. During the surgery, we induced nerve action potentials and compound motor action potentials across the ganglion cyst, which demonstrated neural continuity. Outcomes: Three months after the surgery, the patient showed partial recovery of wrist and finger extensor muscle power. An electrodiagnostic test conducted 3 months after the surgery showed reinnervation potentials in PIN-innervated muscles. Lessons: IONM during peripheral nerve surgeries can support surgical decisions and confirm the location and degree of nerve damage.

Background Digital infrared thermal imaging (DITI), which detects infrared rays emitted from body surface to create a body heat map, has been utilized at various musculocutaneous conditions. Notably, DITI can demonstrate autonomic vasomotor activity in the nerve-innervated area, and thus may be of use in carpal tunnel syndrome (CTS). In this study, we compared DITI findings before and after carpal tunnel release (CTR) surgery in patients with unilateral CTS to investigate the corresponding neurophysiological changes. Methods In this retrospective cohort study, DITI parameters such as the temperature differences between the median and ulnar nerve territories and median nerve-innervated digital anisometry were measured. Subjective symptom duration, pain scale, and ultrasonographic findings were also compared before and after CTR. Patients were evaluated before and 6 weeks after CTR, respectively. Results A total of 27 patients aged 59.0 ± 11.2 years were finally included. After CTR, median nerve-innervated thermal anisometry was improved (2.55 ± 0.96 °C to 1.64 ± 1.34 °C; p = 0.003). The temperature differences between the median and ulnar nerve territories were not significantly changed. Subjective pain, the Simovic Weinberg Clinical Scale, and palmar bowing of the flexor retinaculum were also significantly improved (p <  0.001 for all comparisons). Conclusions Our results demonstrated that DITI findings could reflect an improvement in autonomic function after CTR. Therefore, DITI can be an objective method to assess pre- and post-operative neurophysiologic changes in CTS.

Background Digital infrared thermal imaging (DITI) is a useful tool for assessing carpal tunnel syndrome (CTS). Notably, this can demonstrate autonomic vasomotor activity in the nerve-innervated area. In this study, we compared DITI findings before and after carpal tunnel release (CTR) surgery in patients with unilateral CTS to investigate the corresponding neurophysiological changes. Methods DITI parameters such as the temperature differences between the median and ulnar nerve territories and median nerve-innervated digital anisometry were measured. Subjective symptom duration, pain scale, and ultrasonographic findings were also compared before and after CTR. Patients were evaluated before and six weeks after CTR, respectively. Results A total of 27 patients aged 59.0 ± 11.2 years were finally included. After CTR, median nerve-innervated thermal anisometry was improved (2.55 ± 0.96 ℃ to 1.64 ± 1.34 ℃; p = 0.003). The temperature differences between the median and ulnar nerve territories were not significantly changed. Subjective pain, the Simovic Weinberg Clinical Scale, and palmar bowing of the flexor retinaculum were also significantly improved (p < 0.001 for all comparisons). Conclusions Our results demonstrated that DITI findings could reflect an improvement in autonomic function after CTR. Therefore, DITI can be an objective method to assess pre- and post-operative neurophysiologic changes in CTS.