Does Ipsilateral Remapping Following Hand Loss Impact Motor Control of the Intact Hand?

What happens once a cortical territory becomes functionally redundant? We studied changes in brain function and behavior for the remaining hand in humans (male and female) with either a missing hand from birth (one-handers) or due to amputation. Previous studies reported that amputees, but not one-handers, show increased ipsilateral activity in the somatosensory territory of the missing hand (i.e., remapping). We used a complex finger task to explore whether this observed remapping in amputees involves recruiting more neural resources to support the intact hand to meet greater motor control demands. Using basic fMRI analysis, we found that only amputees had more ipsilateral activity when motor demand increased; however, this did not match any noticeable improvement in their behavioral task performance. More advanced multivariate fMRI analyses showed that amputees had stronger and more typical representation-relative to controls' contralateral hand representation-compared with one-handers. This suggests that in amputees, both hand areas work together more collaboratively, potentially reflecting the intact hand's efference copy. One-handers struggled to learn difficult finger configurations, but this did not translate to differences in univariate or multivariate activity relative to controls. Additional white matter analysis provided conclusive evidence that the structural connectivity between the two hand areas did not vary across groups. Together, our results suggest that enhanced activity in the missing hand territory may not reflect intact hand function. Instead, we suggest that plasticity is more restricted than generally assumed and may depend on the availability of homologous pathways acquired early in life.

Predicting Prosthetic Mobility at Discharge From Rehabilitation Following Major Amputation in Vascular Surgery.

OBJECTIVE: This study aimed to construct a decision aid to estimate the likelihood of independence with a prosthesis following rehabilitation for limb loss secondary to advanced ischaemia (acute or chronic limb threatening ischaemia) or diabetic foot disease (DFD). A secondary aim was to determine whether prosthetic independence is a surrogate marker of long term survival. METHODS: A retrospective cohort study of a prospectively maintained database of unilateral amputations due to ischaemia or DFD entering rehabilitation between 2007 and 2020 was performed. Predictors of independent prosthetic mobility (IPM) were used in construction of the IPM prediction model, which underwent bootstrap internal and criterion validation through correlation with predictors of other measures of function: Timed Up and Go (TUG) and two minute walk test. Kaplan-Meier and Cox regression analyses were performed to address the secondary aim. RESULTS: Of the 771 patients included, only 49.9% of amputees achieved IPM. Independent negative predictors of IPM were age > 75 years, female sex, higher amputation level, active malignancy, cerebrovascular disease, end stage renal disease, and cognitive impairment. The model yielded high discrimination (C statistic 0.778), and internal validation was demonstrated with bootstrapping (C statistic 0.778), confirming no over optimism. There was a strong correlation between IPM, TUG, and two minute distance and their predictors, confirming strong criterion validity. The IPM group had a median survival of 93.7 (80.7, 105) months, whereas the non-IPM group fared worse with a median survival of 56.6 (48.5, 66.7) months (p < .001). CONCLUSION: An internally validated decision aid for estimating the likelihood of independence with a prosthesis after major amputation was constructed. A strong association between female sex and poorer prosthetic mobility was observed. Prosthetic function was shown to be a surrogate marker of long term survival. Future research will involve external validation studies to confirm the generalisability of the decision aid in clinical practice.

Association between statin-use and mobility and long-term survival after major lower limb amputation.

AIM: The aim of this study was to determine if there is an association between statin-use and prosthetic mobility and long-term survival in patients receiving rehabilitation after major amputation for lower limb arterial disease. METHODS: A retrospective analysis of prospectively maintained data (2008-2020) from a centre for rehabilitation was performed. Patients were grouped by statin-use status and sub-grouped by the combination of statin and antithrombotic drugs (antiplatelets or anticoagulants). Outcomes were prosthetic mobility (SIGAM score, timed-up-go and 2-min walking distance) and long-term survival. Regression, Kaplan-Meier and Cox-proportional hazard analyses were performed to test associations adjusted to confounders. RESULTS: Of 771 patients, 499 (64.7%) were on a statin before amputation or prescribed a statin peri-operatively. Rate of statin-use was significantly lower among female (53.3%) compared to male (68.2%) patients, P < 0.001. Statin-use was associated with significantly better prosthetic independence (53.1% vs 44.1%, P = 0.017), timed-up-go (mean difference of 4 s, P = 0.04) and long-term survival HR 0.59 (0.48-0.72, P < 0.001). Significance persisted after adjusting for confounding factors and in subgroup analyses. The combination of statin with antiplatelet was associated with the most superior survival, HR 0.51 (0.40-0.65, P < 0.001). Sensitivity analysis (exclusion of non-users of prosthesis) showed that statin-use remained a significant indicator of longer survival, maximally when combined with antiplatelet use HR 0.52 (0.39-0.68, P < 0.001). CONCLUSIONS: Statin-use is associated with better mobility and long-term survival in rehabilitees after limb loss, particularly when used in combination with antiplatelets. Significantly lower rates of statin-use were observed in female patients. Further research is warranted on gender disparities in statin-use and causality in their association with improved mobility and survival.

Amputation of the Unsalvageable Leg in Vascular Patients with Cancer.

OBJECTIVES: The aim of this study was to compare outcomes of major lower limb amputation (MLA) in patients with and without cancer and with cancer patients receiving palliation over amputation for their unsalvageable limb. METHODS: Cancer patients who underwent a major amputation or palliation between 2013 and 2018 were included. Comparison groups were cancer-MLA (active/managed cancers), non-cancer MLA (historic cancer or no cancer history) and cancer-palliation at presentation with unsalvageable limbs. Prospectively collected data was retrospectively analysed for outcomes including survival, postoperative complications, length of stay, suitability for rehabilitation and discharge destination. RESULTS: 262 (cancer and non-cancer) patients underwent MLA and 18 patients with cancer received palliation. Of those amputated, 26 (9.9%) had active or managed cancer, of which 12 were diagnosed in the 6 months before MLA. Cancer-MLA patients presented with more acute ischaemia compared to non-cancer patients. Median survival was significantly different between the cancer-MLA (14.1 [9.5 - 29.5, 95% CI] months), non-cancer MLA (57.7 [45 - 73.6, 95% CI] months) and cancer-palliation (.6 [.4 - 2.3, 95% CI] months) groups, P < .001. A significantly higher proportion of cancer-MLA patients (10/26, 38.5%) were deemed unsuitable for rehabilitation in post-operative assessment compared to non-cancer MLA (21/236, 8.9%) patients, P < .001. There was a variation in destinations of discharge, with a greater proportion of cancer-MLA patients (4/26, 15.4%) going to a nursing home compared to non-cancer MLA (10/236, 4.2%) patients, P = .016. CONCLUSION: Cancer is prevalent among vascular amputees, with a large proportion being occult diagnoses. Cancer is associated with poorer outcomes following amputation, but survival remains significantly better compared to palliation in cancer patients presenting with unsalvageable limbs.

A Proposal for Expansion of the Medical Specialty of Rehabilitation Medicine.

The workforce of the medical specialty of Rehabilitation Medicine (RM) in the UK is 10 times less than the European average for the specialty of Physical and Rehabilitation Medicine (PRM). This can be explained partly by the difference in the scope of practice within the specialty between the UK and other European countries and USA. This opinion paper aims to compare the rehabilitation needs in chronic medical conditions and compare the scope of practice between countries within Europe and other regions of the world. The potential advantages of a broader remit specialty to improve rehabilitation care for patients by involving rehabilitation physicians in various medical conditions is explored. Recommendations have been put forward in the Rehabilitation Medicine Expansion Proposal (RMEP), which is likely to make the medical specialty of RM/ PRM more satisfying for the doctors working in the specialty and a more attractive career choice for those entering training in the specialty. There is a need for an international universal framework for the scope of the specialty to have a greater impact on improving the lives of those with chronic medical conditions.