Local neuromuscular characteristics associated with patellofemoral pain: A systematic review and meta-analysis

BACKGROUND

Local neuromuscular deficits have been reported in people with patellofemoral pain. We synthesised the neuromuscular characteristics associated with patellofemoral pain to help identify interventional targets and potential mechanisms.

METHODS

Five databases were searched for local neuromuscular characteristics in case-control studies. Electromyography, flexibility, muscle performance and cross-sectional area data were derived from functional or isolated task investigations and synthesised accordingly. An evidence gap map was constructed.

FINDINGS

Sixty-seven studies were included. In functional tasks, electromyographic investigations showed moderate evidence of small effect for vastus medialis onset-delays relative to vastus lateralis (0.44 [0.03, 0.85]) during stepping/stair negotiation tasks, and higher biceps femoris mean excitation amplitudes (0.55 [0.06, 1.04]) in single-leg triple-hop test. In isolated tasks, we found moderate evidence of medium effect for lower Hoffman-reflex amplitude of vastus medialis (-1.12 [-1.56, -0.67]). Muscle performance investigations showed; strong evidence with medium and small effects for lower extensors concentric (-0.61 [-0.81, -0.40]) and eccentric (-0.56 [-0.79, -0.33]) strength, and moderate evidence of medium effect of lower isometric (-0.64 [-0.87, -0.41]) strength, moderate evidence with small effect for rate of force development to 30% (-0.55[-0.89, -0.21]), 60% (-0.57[-0.90, -0.25]) and medium effect to 90% (-0.76[-1.43, -0.10]) of maximum voluntary contraction, and small effect for lower flexors concentric strength (-0.46 [-0.74, -0.19]) and extensors total work (-0.48 [-0.90, -0.07]). Flexibility investigations showed tighter hamstrings (-0.57 [-0.99, -0.14]).

INTERPRETATION

Differences within quadriceps and hamstrings motor-control, hamstrings tightness, and quadriceps and hamstrings weakness are associated with patellofemoral pain, and can be used to guide investigations of treatment effects.

Genetic analysis of neurodegenerative diseases in a pathology cohort

Molecular genetic research provides unprecedented opportunities to examine genotype-phenotype correlations underlying complex syndromes. To investigate pathogenic mutations and genotype-phenotype relationships in diverse neurodegenerative conditions, we performed a rare variant analysis of damaging mutations in autopsy-confirmed neurodegenerative cases from the Johns Hopkins Brain Resource Center (n = 1243 patients). We used NeuroChip genotyping and C9orf72 hexanucleotide repeat analysis to rapidly screen our cohort for disease-causing mutations. In total, we identified 42 individuals who carried a pathogenic mutation in LRRK2, GBA, APP, PSEN1, MAPT, GRN, C9orf72, SETX, SPAST, or CSF1R, and we provide a comprehensive description of the diverse clinicopathological features of these well-characterized cases. Our study highlights the utility of high-throughput genetic screening arrays to establish a molecular diagnosis in individuals with complex neurodegenerative syndromes, to broaden disease phenotypes and to provide insights into unexpected disease associations.

Genome-wide Analyses Identify KIF5A as a Novel ALS Gene

To identify novel genes associated with ALS, we undertook two lines of investigation. We carried out a genome-wide association study comparing 20,806 ALS cases and 59,804 controls. Independently, we performed a rare variant burden analysis comparing 1,138 index familial ALS cases and 19,494 controls. Through both approaches, we identified kinesin family member 5A (KIF5A) as a novel gene associated with ALS. Interestingly, mutations predominantly in the N-terminal motor domain of KIF5A are causative for two neurodegenerative diseases: hereditary spastic paraplegia (SPG10) and Charcot-Marie-Tooth type 2 (CMT2). In contrast, ALS-associated mutations are primarily located at the C-terminal cargo-binding tail domain and patients harboring loss-of-function mutations displayed an extended survival relative to typical ALS cases. Taken together, these results broaden the phenotype spectrum resulting from mutations in KIF5A and strengthen the role of cytoskeletal defects in the pathogenesis of ALS.

Age-related penetrance of the C9orf72 repeat expansion

A pathogenic hexanucleotide repeat expansion within the C9orf72 gene has been identified as the major cause of two neurodegenerative syndromes, amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). This mutation is known to have incomplete penetrance, with some patients developing disease in their twenties and a small portion of carriers surviving to their ninth decade without developing symptoms. Describing penetrance by age among C9orf72 carriers and identifying parameters that alter onset age are essential to better understanding this locus and to enhance predictive counseling. To do so, data from 1,170 individuals were used to model penetrance. Our analysis showed that the penetrance was incomplete and age-dependent. Additionally, familial and sporadic penetrance did not significantly differ from one another; ALS cases exhibited earlier age of onset than FTD cases; and individuals with spinal-onset exhibited earlier age of onset than those with bulbar-onset. The older age of onset among female cases in general, and among female bulbar-onset cases in particular, was the most striking finding, and there may be an environmental, lifestyle, or hormonal factor that is influencing these penetrance patterns. These results will have important applications for future clinical research, the identification of disease modifiers, and genetic counseling.

NeuroChip, an updated version of the NeuroX genotyping platform to rapidly screen for variants associated with neurological diseases

Genetics has proven to be a powerful approach in neurodegenerative diseases research, resulting in the identification of numerous causal and risk variants. Previously, we introduced the NeuroX Illumina genotyping array, a fast and efficient genotyping platform designed for the investigation of genetic variation in neurodegenerative diseases. Here, we present its updated version, named NeuroChip. The NeuroChip is a low-cost, custom-designed array containing a tagging variant backbone of about 306,670 variants complemented with a manually curated custom content comprised of 179,467 variants implicated in diverse neurological diseases, including Alzheimer's disease, Parkinson's disease, Lewy body dementia, amyotrophic lateral sclerosis, frontotemporal dementia, progressive supranuclear palsy, corticobasal degeneration, and multiple system atrophy. The tagging backbone was chosen because of the low cost and good genome-wide resolution; the custom content can be combined with other backbones, like population or drug development arrays. Using the NeuroChip, we can accurately identify rare variants and impute over 5.3 million common SNPs from the latest release of the Haplotype Reference Consortium. In summary, we describe the design and usage of the NeuroChip array and show its capability for detecting rare pathogenic variants in numerous neurodegenerative diseases. The NeuroChip has a more comprehensive and improved content, which makes it a reliable, high-throughput, cost-effective screening tool for genetic research and molecular diagnostics in neurodegenerative diseases.

The health of caregivers for children with disabilities: caregiver perspectives

BACKGROUND

There are an estimated 5.9 million children with severe disabilities in the USA, and most of them are cared for at home by their parents and families. Indirect evidence suggests that poor caregiver health may contribute to recurrent hospitalizations and out-of-home placements for children with chronic conditions and disabilities. Greater knowledge of caregiver health-related needs would allow for the improvement of existing services and the development of new strategies to sustain caregivers in their vital roles. This study explores caregiver perspectives of the health implications of long-term informal caregiving for children with disabilities.

METHODS

Forty parents/caregivers of children with disabilities residing in urban, suburban and rural regions of Utah completed questionnaires and participated in focus groups that explored their feelings regarding their current physical and emotional health and the factors that they viewed as either impairing or promoting their health. The sessions were audiotaped and transcribed. Summary statistics were generated for the questionnaire responses. Focus group content was analysed according to emerging themes and patterns in clusters of information.

RESULTS

The caregiving experience was captured by five themes: (i) stress of caregiving; (ii) negative impact on caregiver health; (iii) sharing the burden; (iv) worry about the future; and (v) caregiver coping strategies. Forty-one per cent of the caregivers reported that their health had worsened over the past year, and attributed these changes to a lack of time, a lack of control and decreased psychosocial energy.

CONCLUSIONS

Caregivers of children with disabilities describe negative physical, emotional and functional health consequences of long-term, informal caregiving. They have important insights regarding those aspects of caregiving that have positive and negative influences on their health. Interventions that address these issues may have the potential to positively impact caregiver health.

Costs and complications of hospitalizations for children with cerebral palsy

BACKGROUND

Although many children with cerebral palsy (CP) develop secondary conditions requiring hospitalization, in-patient hospital utilization by this population has not been characterized.

OBJECTIVE

To characterize hospitalizations in children with CP and to compare them with hospitalizations of those without CP using a large national data set.

METHODS

Analysis of the Healthcare Utilization Project Kid Inpatient Database, a weighted survey of paediatric discharges from US hospitals in 1997.

RESULTS

In 1997, 37,000 children with CP were hospitalized, generating charges approaching 600 million dollars. Children with CP demonstrated longer lengths of stay (6.3 vs 4.1 days, p < 0.001), higher total charges (16,024 vs 9952 dollars, p < 0.001), more diagnoses (5.6 vs 3.0, p < 0.001) and more procedures (1.7 vs 1.1, p < 0.001) per admission. Five major diagnostic categories accounted for 83.2% of the discharge diagnoses for children with CP (48.6% for those without CP, p < 0.001). Children with CP were more often transferred to other facilities (p < 0.001) or prescribed home health care (p < 0.001) upon discharge.

CONCLUSIONS

Hospitalization of children with CP represents a major expenditure for health care systems. Studies to improve the management of conditions associated with CP could result in better outcomes for children and families and potentially decrease costs associated with hospitalization.

Consideration of alternative accounts of gender-linked speech patterns in individuals with mental retardation

Several preliminary reports have reported the existence of gender influences on the communication patterns of individuals with mental retardation. This study considers two alternative hypotheses to the conclusion that the reported effects were attributable to gender. Two studies extend a previous analysis by further exploration of the original transcripts (Study 1) and addition of participants (Study 2). In Study 1, the possibility of influences from adult partners is analyzed. In Study 2, the association of syntactic development and gender-linked effects is examined. Both alternatives are rejected on the basis of these extended analyses.

References to people in the communications of female and male youths with mental retardation

Gender-related differences have consistently been reported in the language of adults and children with no disabilities. One well-replicated finding is that females discuss people and relationships more often than do males, particularly in conversations with other females. These stylistic variations in language are considered to have implications for the adaptive functioning of language users, most particularly females. Although studied thus far only in nondisabled individuals, such issues of language style use may be of equal or greater concern for those with mental retardation. How does a cognitive impairment intensify or reduce gender-linked language styles and their effects? Language transcripts were obtained from eight male and eight female participants with retardation, interacting separately with one male and one female adult partner. Half of the participants used speech as their primary mode of communication: the others relied on vocalization, gesture, or augmented modes. Participants using speech showed gender-linked language patterns similar to nondisabled individuals, with females discussing people significantly more often than males. Females using nonspeech modes, in contrast, showed a severe reduction in person-referencing that was not accountable by their expressive speech limitations.