A case of iatrogenic acute spinal cord injury with tetraplegia following thyroid surgery.

AIM: Iatrogenic acute spinal cord injury with tetraplegia is a serious consequence of non-spinal surgery.We report a case of acute spinal cord injury with tetraplegia after thyroid surgery. METHOD: The patient was pathologically diagnosed with papillary carcinoma, underwent left thyroidectomy, and developed tetraplegia after surgery. RESULT: The patient was diagnosed with acute spinal cord injury with tetraplegia and cured after anti-inflammatory and dehydrating treatment. CONCLUSION: Iatrogenic spinal cord injuries after elective non-spinal surgery can have catastrophic consequences, and clinicians must be alert to this possibility in clinical practice.

Surgical procedures to improve hand function in tetraplegic patients: patient satisfaction and outcomes over a 20-year period.

The aim of the present study was to report our experience in the evolution in surgical strategy and patient satisfaction after upper limb reconstruction in tetraplegic patients. A total of 72 patients (114 upper limbs) underwent surgery between 1997 and 2017. Since April 2003, tenodesis of the extensor digitorum communis tendons was no longer performed because it limited wrist flexion, and two-stage operations to restore active grasp were replaced by one-stage procedures. In total, 34 patients (58 upper limbs) completed questionnaires about function and satisfaction at a mean follow-up of 14 years (range 4-24) since their first operation; 26 were satisfied, 30 would have the operation again and 31 benefitted from the surgery. Surgical procedures, such as tendon transfers, arthrodesis and tenodesis, can have a positive effect on patient-perceived function and satisfaction in the long term in most of these patients.Level of evidence: IV.

Implicit and explicit motor imagery ability after SCI: Moving the elbow makes the difference.

Cervical spinal cord injury (SCI) causes dramatic sensorimotor deficits that restrict both activity and participation. Restoring activity and participation requires extensive upper limb rehabilitation focusing elbow and wrist movements, which can include motor imagery. Yet, it remains unclear whether MI ability is impaired or spared after SCI. We investigated implicit and explicit MI ability in individuals with C6 or C7 SCI (SCIC6 and SCIC7 groups), as well as in age- and gender-matched controls without SCI. Inspired by previous studies, implicit MI evaluations involved hand laterality judgments, hand orientation judgments (HOJT) and hand-object interaction judgments. Explicit MI evaluations involved mental chronometry assessments of physically possible or impossible movements due to the paralysis of upper limb muscles in both groups of participants with SCI. HOJT was the paradigm in which implicit MI ability profiles differed the most between groups, particularly in the SCIC6 group who had impaired elbow movements in the horizontal plane. MI ability profiles were similar between groups for explicit MI evaluations, but reflected task familiarity with higher durations in the case of unfamiliar movements in controls or attempt to perform movements which were no longer possible in persons with SCI. Present results, obtained from a homogeneous population of individuals with SCI, suggest that people with long-term SCI rely on embodied cognitive motor strategies, similar to controls. Differences found in behavioral response pattern during implicit MI mirrored the actual motor deficit, particularly during tasks that involved internal representations of affected body parts.

Leptomeningeal Dissemination Complicated With Acute Tetraplegia From a Supratentorial Multicentric Isocitrate Dehydrogenase (IDH)-Wildtype Glioblastoma: A Case Report.

Glioblastoma (GBM) is a major concern for neurosurgeons and oncologists, being a malignant tumor with a high recurrence rate and reduced survival. Leptomeningeal dissemination (LMD) of GBM is rare and difficult to diagnose due to the low rate of cellular detection in the cerebrospinal fluid and clinical and imaging similarities with fungal and tuberculous meningitis. We report the case of a 25-year-old female patient suffering from multicentric GBM who developed hydrocephalus and extensive LMD three months after surgery for a left frontal parafalcine cerebral GBM isocitrate dehydrogenase (IDH)-wildtype.

Use of an upright power wheelchair in spinal cord injury: a case series.

Objective: To explore independence, usability, and self-reported quality of life (QOL) in eligible persons with spinal cord injury (SCI) who used a standing powered wheelchair over a 12-week period. Setting: VA SCI research facility. Participants: Four participants with chronic SCI who use a wheelchair as the primary means of mobility. Intervention: A standing power wheelchair was used three times a week (3.5 h/session) for 12 weeks in a supervised setting. Main Outcome Measures: safety, usability and feasibility, blood pressure in seated and standing positions, bowel, bladder, and pain item banks from the SCI-QOL Physical-Medical-Health domain, and overall user satisfaction with the device. Results: Participants consistently maintained normal blood pressure responses between seated and standing positions throughout the training sessions and learned to perform all the mobility tasks safely and independently. Participants reported improvements on the SCI-QOL and were generally satisfied with the upright standing power wheelchair. Conclusions: In this small case series of chronic, non-ambulatory individuals with SCI, the standing powered wheelchair was shown to be safe and efficacious.

How Elite Athletes with a Spinal Cord Injury Sweat during Exercise-An Exploratory Study.

BACKGROUND: Sweat and thermal responses in individuals with spinal cord injury (SCI) are impaired depending on lesion characteristics. This is particularly problematic for athletes and may ultimately lead to reduced performance. This exploratory study investigated the feasibility of field-usable methods to objectively collect data relevant to sweat response in elite athletes with SCI. Differences in sweat response were also evaluated for different athlete characteristics. METHODS: Measurements were performed during exercise and included core temperature (Tc), heart rate, urine specific gravity, fluid intake, sweat rate, and sweat electrolyte concentration. Differences for sex, lesion level (tetraplegia versus paraplegia), motor impairment (complete versus incomplete), and sport type (endurance versus team/skill) were evaluated. RESULTS: Fifteen athletes (median (Q1-Q3) age, 30 (28-36) years; three females; 11 with complete lesions) were included. Endurance athletes were measured during indoor performance tests (n = 10), whereas team/skill athletes were measured during training sessions (n = 5). In the mixed exercise intensities, the average Tc was 37.7 (37.3-37.8) °C and the average heart rate was 126 (100-146) bpm. Dehydration, defined as a urine specific gravity > 1.020 ng/mL, was prevalent in six athletes before exercise and in five athletes after exercise. The sweat rate was lower in athletes with tetraplegia (p = 0.02) and in team/skill athletes (p = 0.008). CONCLUSIONS: Collecting sweat and thermal response data from athletes with SCI in the field is feasible. Given the suboptimal hydration status of many athletes, raising awareness of the importance of hydration seems valuable.

Decoding of unimanual and bimanual reach-and-grasp actions from EMG and IMU signals in persons with cervical spinal cord injury.

Objective. Chronic motor impairments of arms and hands as the consequence of a cervical spinal cord injury (SCI) have a tremendous impact on activities of daily life. A considerable number of people however retain minimal voluntary motor control in the paralyzed parts of the upper limbs that are measurable by electromyography (EMG) and inertial measurement units (IMUs). An integration into human-machine interfaces (HMIs) holds promise for reliable grasp intent detection and intuitive assistive device control.Approach. We used a multimodal HMI incorporating EMG and IMU data to decode reach-and-grasp movements of groups of persons with cervical SCI (n = 4) and without (control, n = 13). A post-hoc evaluation of control group data aimed to identify optimal parameters for online, co-adaptive closed-loop HMI sessions with persons with cervical SCI. We compared the performance of real-time, Random Forest-based movement versus rest (2 classes) and grasp type predictors (3 classes) with respect to their co-adaptation and evaluated the underlying feature importance maps.Main results. Our multimodal approach enabled grasp decoding significantly better than EMG or IMU data alone (p<0.05). We found the 0.25 s directly prior to the first touch of an object to hold the most discriminative information. Our HMIs correctly predicted 79.3 ± STD 7.4 (102.7 ± STD 2.3 control group) out of 105 trials with grand average movement vs. rest prediction accuracies above 99.64% (100% sensitivity) and grasp prediction accuracies of 75.39 ± STD 13.77% (97.66 ± STD 5.48% control group). Co-adaption led to higher prediction accuracies with time, and we could identify adaptions in feature importances unique to each participant with cervical SCI.Significance. Our findings foster the development of multimodal and adaptive HMIs to allow persons with cervical SCI the intuitive control of assistive devices to improve personal independence.

Which PDE5 inhibitor is the most effective in the treatment of erectile dysfunction in men with spinal cord injury? A systematic review and network meta-analysis.

BACKGROUND: Phosphodiesterase 5 inhibitors (PDE5i) are the first-line drugs for erectile dysfunction (ED) but differences among available molecules should drive therapy personalization. Choosing one PDE5i over another is a challenge in men with spinal cord injury (SCI), as the evidence of efficacy for each molecule is derived from few studies and comparative "head-to-head" trials are lacking. OBJECTIVE: To assess the efficacy of the different PDE5i for SCI-related ED with a network meta-analysis (NMA) approach. MATERIALS AND METHODS: Databases from PubMed, Web of Science, Scopus, and Cochrane Library were checked for randomized controlled trials (RCTs) comparing any PDE5i to each other or placebo in men with traumatic SCI lasting ≥6 months. Data were incorporated in a random-effect NMA, where treatments' efficacy was ranked using the surface under the cumulative ranking curve (SUCRA). RESULTS: The 10 RCTs included provided information about 1,492 men with ED due to traumatic SCI. Intervention arms included sildenafil, tadalafil, and/or vardenafil. Overall, at the pairwise meta-analysis, PDE5i were four times more effective than placebo in improving erectile function (risk ratio: 4.13, 95% CI: 2.76, 6.19). The comparative analysis from NMA revealed that tadalafil was associated with the highest SUCRA value (81%), followed by vardenafil (68%) and sildenafil (49%). DISCUSSION AND CONCLUSION: Within the grading of comparison network, tadalafil appeared to be the best PDE5i in the treatment of SCI-related ED. Further focused studies are warranted to confirm these findings and define optimal doses and duration of therapy.

Corticospinal inhibition investigated in relation to upper extremity motor function in cervical spinal cord injury.

OBJECTIVE: Corticospinal inhibitory mechanisms are relevant to functional recovery but remain poorly understood after spinal cord injury (SCI). Post-injury characteristics of contralateral silent period (CSP), a measure of corticospinal inhibition evaluated using transcranial magnetic stimulation (TMS), is inconsistent in literature. We envisioned that investigating CSP across muscles with varying degrees of weakness may be a reasonable approach to resolve inconsistencies and elucidate the relevance of corticospinal inhibition for upper extremity function following SCI. METHODS: We studied 27 adults with chronic C1-C8 SCI (age 48.8 ± 16.1 years, 3 females) and 16 able-bodied participants (age 33.2 ± 11.8 years, 9 females). CSP characteristics were assessed across biceps (muscle power = 3-5) and triceps (muscle power = 1-3) representing stronger and weaker muscles, respectively. We assessed functional abilities using the Capabilities of the Upper Extremity Test (CUE-T). RESULTS: Participants with chronic SCI had prolonged CSPs for biceps but delayed and diminished CSPs for triceps compared to able-bodied participants. Early-onset CSPs for biceps and longer, deeper CSPs for triceps correlated with better CUE-T scores. CONCLUSIONS: Corticospinal inhibition is pronounced for stronger biceps but diminished for weaker triceps muscle in SCI indicating innervation relative to the level of injury matters in the study of CSP. SIGNIFICANCE: Nevertheless, corticospinal inhibition or CSP holds relevance for upper extremity function following SCI.

Comparison of multidirectional upper limb strength for non-disabled individuals and individuals with C4-C7 spinal cord injury in a seated position.

This study investigates the multidirectional upper limb strength of individuals with a C4-C7 spinal cord injury (SCI) and non-disabled individuals in a seated position by measuring multidirectional force at the hand. Current literature lacks quantitative strength data to evaluate strength requirements for people who have reduced upper limb function due to a cervical SCI. Seated multidirectional force measurements were recorded for eleven non-disabled and ten males with a C4-C7 SCI. Collected data was displayed using detailed force polar plots. The resulting plots revealed a clear difference in polar plot shape for non-disabled participants and participants with a C4-C7 SCI. Namely that SCI participants had more elliptical polar plots due to reductions in circumferential strength compared to non-disabled participants. However, the polar plots for higher SCIs tended to have an increasingly more circular shape. The results provide insight into the differences in strength between people with cervical SCI and no disability.

This paper presents seated multidirectional arm strength data from 21 SCI and non-disabled participants. Force polar plots display the applied force magnitudes and directions for reachable points which can be used to evaluate the force requirements based on SCI level. Results highlighted strength reductions for people with higher SCIs.

Shoulder Pain in Persons With Tetraplegia and the Association With Force Application During Manual Wheelchair Propulsion.

Objective: To investigate the association between propulsion biomechanics, including force application and spatio-temporal characteristics, and shoulder pain in persons with tetraplegia. Design: Cross-sectional, observational study. Setting: Non-university research institution. Participants: 16 community dwelling, wheelchair dependent persons with a chronic tetraplegia between C4 and C7, with and without shoulder pain (age, 49.1±11.7 years; 94% men, 23.4±9.5 years past injury). Interventions: Not applicable. Main Outcome Measures: Force application and spatio-temporal characteristics of wheelchair propulsion on a treadmill (0.56 m/s, 10W and 0.83 m/s, 15W). Participants were stratified in groups with low, moderate, and high pain based on their Wheelchair User Shoulder Pain Index (WUSPI) score on the day of measurement. Results: The mixed-effect multilevel analysis showed that wheelchair users with high levels of shoulder pain applied propulsion force more effectively (and with a lower medial component) and over a longer push angle, thus shortening the recovery time as compared with persons with low or moderate levels of shoulder pain. Conclusions: In contrast with previous results from persons with a paraplegia, persons with tetraplegia and high levels of shoulder pain propel their wheelchair more optimal with regard to risk factors for shoulder pain. Our results therefore affirm that there is a different interaction of shoulder pain and propulsion biomechanics in persons with a tetraplegia which should be considered when further analyzing risk factors for shoulder pain in wheelchair users or applying literature results to different patient populations.

Prevalences of sleep-related breathing disorders and severity factors in chronic spinal cord injury and abled-bodied individuals undergoing rehabilitation: a comparative study.

STUDY OBJECTIVES: The objective of this study is to discern distinguishing characteristics of sleep-related breathing disorders (SRBD) in individuals with chronic spinal cord injury (CSCI) compared to able-bodied participants (non-CSCI). Additionally, the study investigates factors associated with SRBD severity. METHODS: This is a cross-sectional analysis of 123 able-bodied individuals, 40 tetraplegics, and 48 paraplegics, who underwent attended or partially supervised full polysomnography, for suspected SRBD, in a rehabilitation center. Polysomnographic, transcutaneous capnography, and clinical data were collected and compared between the groups. RESULTS: Among tetraplegics prevailed apnea-hypopnea index ≥ 30 (67.5%, p=0.003), central apnea (17.5%, p=0.007), and higher oxygen-desaturation index (80.0%, p=0.01). Sleep-related hypoventilation was present in 15,4% of tetraplegics and 15,8% of paraplegics, compared to 3,2% in able-bodied participants (p=0.05). In the able-bodied and paraplegic groups, snoring and neck circumference were positively correlated with obstructive sleep apnea (OSA) severity. A positive correlation between waist circumference and OSA severity was identified in all groups, and multivariate logistic regression analysis showed that loud snoring and waist circumference had the greatest impact on OSA severity. CONCLUSIONS: Severe OSA and Central Sleep Apnea prevailed in tetraplegic participants. Sleep-related hypoventilation was more common in tetraplegics and paraplegics compared to able-bodied participants. Loud snoring and waist circumference had an impact on OSA severity in all groups. We recommend the routine implementation of transcutaneous capnography in individuals with CSCI. We underscore the significance of conducting a comprehensive sleep assessment in the rehabilitation process of individuals with CSCI.

Experiencing the unreal. Mapping patient journeys from injury towards rehabilitation for a life with tetraplegia.

When patients are brought to the emergency room with a traumatic injury to the spinal cord, the road to recovery is long and uncertain. In minutes, their lives have been irreversibly altered. Time will tell if the paralysis to the limbs is permanent or if some degree of mobility or sensation can be reacquired. To many patients, the first weeks feel almost unreal. They find themselves in a state of shock, and feelings of uncertainty and loss of control are dominating. Spinal cord injuries are treated in multiple specialized hospital units. Each unit is accountable for providing the best possible treatment within their area of expertise. While continuity in care has been a hot research topic for the past 20 years, few studies provide empirical data on patients' perspectives on long-term hospital treatments. This study examines how patients with tetraplegia experience continuity in care when they journey across multiple hospital units over the course of several months. This paper is based on a study of patient pathways for patients with tetraplegia caused by high spinal cord injuries. Semi-structured interviews were conducted with nine patients, seven next of kin and thirteen healthcare professionals in Copenhagen University Hospital. Data from the interviews were analyzed using patient journey mapping, to uncover variations in patients' experience during various stages of their admission. The study finds that patients are struggling to maintain a sense of control over their life as they continuously engage in negotiations of perceptions of their body, of the physical surroundings and of their perception of time and the future. The study concludes that health care professionals should be mindful of these key themes to support the patients' empowerment and active participation during recovery.

Diagnostic and Management Challenges of Esophageal Rupture with Concomitant Cervical Abscess in Chronic High Cervical Tetraplegia.

A 65-year-old with a history of spinal cord injury and previous cervical surgery presented with persistent fever despite antibiotic treatment. MRI scans revealed an abscess in the neck extending from C3 to C6, with associated osteomyelitis. After an initial discharge following antibiotic therapy, the patient was readmitted due to recurrent systemic infection symptoms and another abscess. A subsequent endoscopy showed esophageal rupture with protruding cervical fusion metal. Due to operative risks, a percutaneous endoscopic gastrostomy was performed without further infection recurrence. The absence of typical imaging signs of esophageal rupture made diagnosis difficult. The infection spread through the cervical fascia from superficial to deep cervical areas. Esophageal rupture, a rare complication of cervical surgery, presents with varying symptoms depending on its location and was particularly challenging to diagnose in this patient due to high cervical tetraplegia, which masked typical pain responses. Therefore, this case highlights the need to consider esophageal rupture in differential diagnoses for chronic ACDF patients, even when typical symptoms are absent.

Our experience with the surgical management of lower cervical spine fractures: fifty case series.

PURPOSE: Trauma to the lower cervical spine is a serious lesion due to its neurological consequences which jeopardize the vital and functional prognosis. They constitute a public health problem due to their frequency and seriousness requiring rapid and adequate treatment. The aim of our study is to (1) describe the epidemiological, clinical, and radiological characteristics of lower cervical spine trauma patients; (2) support the therapeutic management of these patients and show our experience in surgery for lower cervical spine trauma; and (3) analyze the anatomical and functional results and discuss them with literature data. METHODS: This is a retrospective descriptive study of 50 patients with lower cervical spine trauma treated surgically over a period of five years from January 1, 2016, to December 2020. RESULTS: The average age of our patients was 34.5 years, with a sex ratio of 1.7. The etiologies are dominated by accidents on public roads (58%). They show neurological disorders such as spinal cord damage in 30% of cases and root damage in 20% of cases. The radiological assessment revealed eight tear drops, ten comminuted fractures, 12 severe sprains, 12 biarticular dislocations, six uniarticular dislocations, and two herniated discs. Treatment was surgical in all patients with an anterolateral approach and anterior arthrodesis. The evolution was favourable in 21 patients and stationary in 29 patients. CONCLUSION: Our study concluded that dislocations and fracture dislocations were the predominant type of injury in cases of AVP. Tetraplegia was mainly observed with uni- and biarticular dislocations. The variation in consolidation time was not correlated with trauma-to-surgery time. Better neurological recovery was observed with mild initial neurological damage than with initially severe damage. The appearance of an adjacent syndrome is less frequent with monosegmental arthrodesis than with multisegmental arthrodesis. Cage arthrodesis was an alternative to iliac harvesting with similar results.

Comparing surgeries to restore upper extremity function in tetraplegia: Impact on function during the perioperative period.

CONTEXT/OBJECTIVE: To assess short-term changes in health outcomes in people with cervical-level spinal cord injury (SCI) who underwent upper extremity (UE) reconstruction via either novel nerve transfer (NT) or traditional tendon transfer (TT) surgery with individuals who did not undergo UE surgical reconstruction. DESIGN: Prospective, comparative cohort pilot study. PARTICIPANTS: 34 participants with cervical SCI met the following inclusion criteria: age 18 or older, greater than 6 months post-injury, and mid-cervical level SCI American Spinal Injury Association Impairment Scale (AIS) A, B or C. SETTING: Two tertiary academic hospitals and their affiliated veterans' hospitals. METHODS: Health outcomes were assessed using two previously validated measures, the Spinal Cord Independence Measure (SCIM) and Short-Form Health Survey (SF-36). Demographic, surgical, and survey data were collected at the initial evaluation and one month postoperatively/post-baseline. RESULTS: 34 participants with cervical SCI were recruited across three cohorts: no surgery (n = 16), NT (n = 10), and TT (n = 8). The TT group had a decline in SCIM and SF-36 scores whereas the NT and no surgery groups experienced little change in independence or health status in the immediate perioperative period. CONCLUSIONS: Surgeons and rehabilitation providers must recognize differences in the perioperative needs of people with cervical SCI who chose to have restorative UE surgery. Future work should focus on further investigation of health outcomes, change in function, and improving preoperative counseling and cross-disciplinary management.

Can the Initial Parameters of Functional Scales Predict Recovery in Patients with Complete Spinal Cord Injury? A Retrospective Cohort Study.

Regaining greater independence in performing daily activities constitutes a priority for people with tetraplegia following spinal cord injury (SCI). The highest expectations are connected with the improvement of hand function. Therefore, it is so important for the clinician to identify reliable and commonly applicable prognostic factors for functional improvement. The aim of this study was to conduct an analysis to assess the impact of initial functional factors on the clinical improvement in patients during early neurological rehabilitation (ENR). This study assessed 38 patients with complete SCI aged 17-78 who underwent ENR in 2012-2022. The analysis included the motor score from the AIS (MS), the Barthel Index (BI) and the SCIM scale values at the beginning of the ENR program and after its completion. During ENR, patients achieved a statistically significant improvement in MS, BI and SCIM. The initial MS and the level of neurological injury constituted the predictors of functional improvement during ENR. Significant statistical relationships were observed primarily in the correlations between the initial MS and BI, and the increase in the analyzed functional scales of SCI patients. Higher initial MS may increase the chances of a greater and faster functional improvement during ENR.

Independent association of hypovitaminosis d with non-alcoholic fatty liver disease in people with chronic spinal cord injury: a cross-sectional study.

PURPOSE: Non-alcoholic fatty liver disease (NAFLD) and hypovitaminosis D are highly prevalent in people with spinal cord injury (SCI) and could exert an unfavorable influence on cardiovascular profile and rehabilitation outcomes. We aimed to assess the independent association between low 25-hydroxy vitamin D (25(OH)D) levels and NAFLD in people with chronic (> 1 year) SCI. METHODS: One hundred seventy-three consecutive patients with chronic SCI (132 men and 41 women) admitted to a rehabilitation program underwent clinical/biochemical evaluations and liver ultrasonography. RESULTS: NAFLD was found in 105 patients (60.7% of the study population). They were significantly older and exhibited a poorer leisure time physical activity (LTPA) and functional independence in activities of daily living, a greater number of comorbidities and a higher prevalence of metabolic syndrome (MetS) and its correlates, including lower HDL and higher values of body mass index (BMI), systolic blood pressure, HOMA-index of insulin resistance and triglycerides. 25(OH)D levels were significantly lower in NAFLD (median: 10.6 ng/ml, range: 2.0-31.0) than in non-NAFLD group (22.5 ng/ml, 4.2-51.6). When all these variables were included in a multiple logistic regression analysis, a significant independent association with NAFLD only persisted for lower 25(OH)D levels, a greater number of comorbidities and a poorer LTPA. The ROC analysis revealed that 25(OH)D levels < 18.25 ng/ml discriminated patients with NAFLD with a sensitivity of 89.0% and a specificity of 73.0% (AUC: 85.7%; 95%CI: 79.6-91.7%). NAFLD was exhibited by 83.9% of patients with 25(OH)D levels < 18.25 ng/ml and by 18% of those with 25(OH)D levels ≥ 18.25 ng/ml (p < 0.0001). CONCLUSION: In people with chronic SCI, 25(OH)D levels < 18.25 ng/ml may represent a marker of NAFLD independent of MetS-related features. Further studies are warranted to define the cause-effect relationships of this association.

Different Thumb Positions in the Tetraplegic Hand.

OBJECTIVE: To analyze factors associated with malposition that affects function of the thumb in individuals with tetraplegia. DESIGN: Retrospective cross-sectional study. SETTING: Rehabilitation Center for Spinal Cord Injury. PARTICIPANTS: Anonymized data from 82 individuals (68 men), mean age 52.9±20.2 (SD) with acute/subacute cervical spinal cord injury C2-C8 AIS A-D recorded during 2018-2020. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Motor point (MP) mapping and manual muscle test (MRC) of 3 extrinsic thumb muscles (flexor pollicis longus (FPL), extensor pollicis longus (EPL), and abductor pollicis longus (APL)). RESULTS: 159 hands in 82 patients with tetraplegia C2-C8 AIS A-D were analyzed and assigned to "key pinch" (40.3%), "slack thumb" (26.4%), and "thumb-in-palm" (7.5%) positions. There was a significant (P<.0001) difference between the 3 thumb positions depicted in lower motor neuron (LMN) integrity tested by MP mapping and muscle strength of the 3 muscles examined. All studied muscles showed a significantly different expression of MP and the MRC values (P<.0001) between the "slack thumb" and "key pinch" position. MRC of FPL was significantly greater in the group "thumb-in-palm" compared with "key pinch" position (P<.0001). CONCLUSIONS: Malposition of the thumb due to tetraplegia seems to be related to the integrity of LMN and voluntary muscle activity of the extrinsic thumb muscles. Assessments such as MP mapping and MRC of the 3 thumb muscles enable the identification of potential risk factors for the development of thumb malposition in individuals with tetraplegia.