Selective dorsal rhizotomy for hereditary spastic paraparesis in children

Treatment of ZC4H2 Variant-Associated Spastic Paraplegia with Selective Dorsal Rhizotomy and Intensive Postoperative Rehabilitation: A Case Report

Selective dorsal rhizotomy (SDR) has been used to treat children with spastic cerebral palsy (CP), and its beneficial effect on quality of life and ambulation has been confirmed in long-term follow-up studies. However, the role of SDR in the treatment of spasticity in patients with hereditary spastic paraplegia (HSP) and related disorders is not well-established. Here, we report the first patient with the ZC4H2 variant who underwent SDR to treat spastic paraplegia. Abnormal gait was discovered during a regular checkup at the age of 3 years and 9 months, and she was diagnosed with spastic paraplegia. She was heterozygous for the ZC4H2 variant and underwent SDR at the age of 5 years and 11 months, which alleviated the spasticity. The patient underwent inpatient postoperative rehabilitation for 4 months and continued outpatient physiotherapy after discharge. The Gross Motor Function Measure-88 score and maximum walking speed decreased transiently 1 month postoperatively, but gradually recovered, and continuously improved 6 months postoperatively. SDR and postoperative intensive rehabilitation were effective in improving motor and walking functions up to 6 months after surgery, although long-term follow-up is needed to draw conclusions.

Surgical treatment options for spasticity in children and adolescents with hereditary spastic paraplegia

PURPOSE

To provide an overview of outcome and complications of selective dorsal rhizotomy (SDR) and intrathecal baclofen pump implantation (ITB) for spasticity treatment in children with hereditary spastic paraplegia (HSP).

METHODS

Retrospective study including children with HSP and SDR or ITB. Gross motor function measure (GMFM-66) scores and level of spasticity were assessed.

RESULTS

Ten patients were included (most had mutations in ATL1 (n = 4) or SPAST (n = 3) genes). Four walked without and two with walking aids, four were non-walking children. Six patients underwent SDR, three patients ITB, and one both. Mean age at surgery was 8.9 ± 4.5 years with a mean follow-up of 3.4 ± 2.2 years. Five of the SDR patients were walking. Postoperatively spasticity in the legs was reduced in all patients. The change in GMFM-66 score was + 8.0 (0-19.7 min-max). The three ITB patients treated (SPAST (n = 2) and PNPLA6 (n = 1) gene mutation) were children with a progressive disease course. No complications of surgery occurred.

CONCLUSIONS

SDR is a feasible treatment option in carefully selected children with HSP, especially in walking patients. The majority of patients benefit with respect to gross motor function, complication risk is low. ITB was used in children with severe and progressive disease.

Hereditary spastic paraplegias proteome: common pathways and pathogenetic mechanisms

INTRODUCTION

Hereditary spastic paraplegias (HSPs) are a group of inherited neurodegenerative disorders characterized by progressive spasticity and weakness of the lower limbs. These conditions are caused by lesions in the neuronal pyramidal tract and exhibit clinical and genetic variability. Ongoing research focuses on understanding the underlying mechanisms of HSP onset, which ultimately lead to neuronal degeneration. Key molecular mechanisms involved include axonal transport, cytoskeleton dynamics, myelination abnormalities, membrane trafficking, organelle morphogenesis, ER homeostasis, mitochondrial dysfunction, and autophagy deregulation.

AREAS COVERED

This review aims to provide an overview of the shared pathogenetic mechanisms in various forms of HSPs. By examining disease-causing gene products and their associated functional pathways, this understanding could lead to the discovery of new therapeutic targets and the development of treatments to modify the progression of the disease.

EXPERT OPINION

Investigating gene functionality is crucial for identifying shared pathogenetic pathways underlying different HSP subtypes. Categorizing protein function and identifying pathways aids in finding biomarkers, predicting early onset, and guiding treatment for a better quality of life. Targeting shared mechanisms enables efficient and cost-effective therapies. Prospects involve identifying new disease-causing genes, refining molecular processes, and implementing findings in diagnosis, key for advancing HSP understanding and developing effective treatments.

Treatment of spasticity

Spasticity is characterized by an enhanced size and reduced threshold for activation of stretch reflexes and is associated with "positive signs" such as clonus and spasms, as well as "negative features" such as paresis and a loss of automatic postural responses. Spasticity develops over time after a lesion and can be associated with reduced speed of movement, cocontraction, abnormal synergies, and pain. Spasticity is caused by a combination of damage to descending tracts, reductions in inhibitory activity within spinal cord circuits, and adaptive changes within motoneurons. Increased tone, hypertonia, can also be caused by changes in passive stiffness due to, for example, increase in connective tissue and reduction in muscle fascicle length. Understanding the cause of hypertonia is important for determining the management strategy as nonneural, passive causes of stiffness will be more amenable to physical rather than pharmacological interventions. The management of spasticity is determined by the views and goals of the patient, family, and carers, which should be integral to the multidisciplinary assessment. An assessment, and treatment, of trigger factors such as infection and skin breakdown should be made especially in people with a recent change in tone. The choice of management strategies for an individual will vary depending on the severity of spasticity, the distribution of spasticity (i.e., whether it affects multiple muscle groups or is more prominent in one or two groups), the type of lesion, and the potential for recovery. Management options include physical therapy, oral agents; focal therapies such as botulinum injections; and peripheral nerve blocks. Intrathecal baclofen can lead to a reduction in required oral antispasticity medications. When spasticity is severe intrathecal phenol may be an option. Surgical interventions, largely used in the pediatric population, include muscle transfers and lengthening and selective dorsal root rhizotomy.

Hereditary spastic paraplegia: Genetic heterogeneity and common pathways

Hereditary Spastic Paraplegias (HSPs) are a heterogeneous group of disease, mainly characterized by progressive spasticity and weakness of the lower limbs resulting from distal degeneration of corticospinal tract axons. Although HSPs represent rare or ultra-rare conditions, with reported cases of mutated genes found in single families, overall, with 87 forms described, they are an important health and economic problem for society and patients. In fact, they are chronic and life-hindering conditions, still lacking a specific therapy. Notwithstanding the number of forms described, and 73 causative genes identified, overall, the molecular diagnostic rate varies among 29% to 61.8%, based on recent published analysis, suggesting that more genes are involved in HSP and/or that different molecular diagnostic approaches are necessary. The accumulating data in this field highlight several peculiar features of HSPs, such as genetic heterogeneity, the discovery that different mutations in a single gene can be transmitted in dominant and recessive trait in families and allelic heterogeneity, resulting in the involvement of HSP-genes in other conditions. Based on the observation of protein functions, the activity of many different proteins encoded by HSP-related genes converges into some distinct pathophysiological mechanisms. This suggests that common pathways could be a potential target for a therapy, possibly addressing several forms at once. Furthermore, the overlap of HSP genes with other neurological conditions can further expand this concept.

The Puzzle of Hereditary Spastic Paraplegia: From Epidemiology to Treatment

Inherited neurodegenerative pathology characterized by lower muscle tone and increasing spasticity in the lower limbs is termed hereditary spastic paraplegia (HSP). HSP is associated with changes in about 80 genes and their products involved in various biochemical pathways, such as lipid droplet formation, endoplasmic reticulum shaping, axon transport, endosome trafficking, and mitochondrial function. With the inheritance patterns of autosomal dominant, autosomal recessive, X-linked recessive, and mitochondrial inheritance, HSP is prevalent around the globe at a rate of 1–5 cases in every 100,000 individuals. Recent technology and medical interventions somewhat aid in recognizing and managing the malaise. However, HSP still lacks an appropriate and adequate therapeutic approach. Current therapies are based on the clinical manifestations observed in the patients, for example, smoothing the relaxant spastic muscle and physiotherapies. The limited clinical trial studies contribute to the absence of specific pharmaceuticals for HSPs. Our current work briefly explains the causative genes, epidemiology, underlying mechanism, and the management approach undertaken to date. We have also mentioned the latest approved drugs to summarise the available knowledge on therapeutic strategies for HSP.

Efficacy of Selective Dorsal Rhizotomy and Intrathecal Baclofen Pump in the Management of Spasticity

BACKGROUND

Neurosurgical indications and interventions provided in the management of spasticity have evolved significantly over time. Selective dorsal rhizotomy (SDR) and intrathecal baclofen (ITB) pumps have been used to improve mobility, reduce lower extremity spasticity, and increase quality of life in patients with various diagnoses.

METHODS

Studies describing ITB and SDR outcomes in adult and pediatric patients were identified from Medline and Embase databases. Only publications between January 1990 to January 2021 were included. Combinations of search terms 'Selective Dorsal Rhizotomy', 'Selective Posterior Rhizotomy', 'functional posterior rhizotomy', 'intrathecal baclofen pump', and 'spasticity' were used. Only studies in English language and those that included parameters for lower extremity outcome (i.e., spasticity, ambulation) were included. Only studies describing follow-up 12 months or greater were included. Case reports, reviews without primary data, or inaccessible publications were excluded.

RESULTS

Two hundred and ninety publications between January 1990 to January 2021 were identified. Of these, 62 fit inclusion and exclusion criteria for a total of 1291 adult and 2263 patients. Etiologies in adult and pediatric populations varied substantially with multiple sclerosis, cerebral palsy, and trauma comprising the majority of causes for spasticity in adult patients. In pediatric patients, cerebral palsy was the predominant etiology of spasticity. While outcomes after SDR and ITB varied, both are effective for long-term tone reduction. SDR appeared to have a greater effect on function compared to baseline when comparing relatively similar subgroups. The complication rates for either intervention were significant; ITB had a much greater incidence of wound and hardware adverse events, whereas SDR was associated with a not insignificant incidence of new bladder or sensory deficit.

CONCLUSION

ITB and SDR have demonstrated efficacy and utility for tone reduction in a variety of conditions. The selection of a specific intervention may have a variety of determining features including the etiology of spasticity, age of patient, as well as balancing benefit and complication profiles of each technique. Appropriate patient selection is essential for providing optimal patient outcomes.

Selective Dorsal Rhizotomy for Treatment of Hereditary Spastic Paraplegia-Associated Spasticity in 37 Patients

Background A limited number of publications have described a reduction of spasticity associated with hereditary spastic paraplegia (HSP) after selective dorsal rhizotomy (SDR). Typically, the SDR procedure is performed on patients with spastic cerebral palsy to remove spasticity and to help these patients with ambulatory function. Whether SDR has similar effects on HSP patients, requires further investigation. Thus, we are providing a personal experience of the effects of SDR on this specific cohort of patients. Objectives To examine the safety of SDR, changes in spasticity, and ambulatory function after SDR on patients with HSP. Methods The Institutional Review Board of Washington University School of Medicine approved this study (#201704003). A total of 37 children and adults received SDR for the treatment of HSP-associated spasticity between 1988 and 2021. SDR was performed through an L1 laminectomy, as we previously described in an earlier publication. The patients took part in the follow-up examination either in-person or by email. The follow-up focused on the patients' motor functions (primarily ambulation), adverse effects of SDR, and orthopedic treatments after SDR. Results Of the total 37 patients who participated in this study, 46% were female and 54% were male. The age range of when HSP was diagnosed was one month to 34 years. Six of the patients' diagnoses were made, based on the family history of HSP in six patients and the remaining 31 patients' diagnoses were confirmed by genetic tests. The most common genetic mutations were SPG4 and SPG3A. Of the patients with positive genetic tests, 40% had no family history of HSP. SDR was performed at the age of 2 to 45 years (mean: 14.7 years). The follow-up period ranged from 0 to 33 years (mean: 3.8 years). One patient developed a spinal fluid leak requiring surgical repair. Two patients reported mild numbness in parts of the lower limbs. Spasticity was removed in 33 patients (89%). Four patients (11%) experienced a return in spasticity. Regarding ambulatory function, 11% of patients reported a decline in function. Two patients walked independently before surgery but declined, requiring a wheelchair eight years and seven years, respectively, after surgery for each patient. In contrast, 16% saw an improvement in ambulatory function, improving from walking with a walker to walking independently. The remaining 73% of patients maintained their level of ambulation. These two groups of patients showed improvement in other motor functions and independence.  Conclusions The present analysis suggests the potential role of SDR in the management of spasticity in HSP patients. We found no sign of SDR being a direct cause of deleterious effects on patients with HSP.

Selective dorsal rhizotomy for spasticity of genetic etiology

Objective Selective dorsal rhizotomy (SDR) is most commonly applied in the context of the treatment of the spastic diplegic variant of cerebral palsy (CP). Its role in the treatment of spasticity associated with other conditions is not well-established. We sought to review outcomes following SDR for the treatment of functionally limiting spasticity in the setting of a genetic etiology. Methods A systematic literature review was performed using the databases Ovid Medline, Embase, Cochrane Library, and PubMed based on the PRISMA guidelines. Articles were included if they described the application of SDR for spasticity of genetic etiology. Reported outcomes pertaining to spasticity and gross motor function following SDR were summarized. Results Five articles reporting on 16 patients (10 males, 6 females) met the inclusion criteria, of which four reported on SDR for hereditary spastic paraplegia (HSP) and four on syndromic patients or other inherited diseases, with an overall follow-up ranging from 11 to 252 months. These individuals were found to have several genetic mutations including ALS2, SPG4, and SPG3A. The mean age at the time of surgery was 14.9 years (median 10 years, range 3-37 years). Conclusions Although all patients experienced a reduction in spasticity, the long-term gross motor functional outcomes objectively assessed at last follow-up were heterogeneous. There may be a role for SDR in the context of static genetic disorders causing spasticity. Further evidence is required prior to the widespread adoption of SDR for such disorders as, based on the collective observations of this review, spasticity is consistently reduced but the long-term effect on gross motor function remains unclear.

Management of Hereditary Spastic Paraplegia: A Systematic Review of the Literature

The term hereditary spastic paraplegia (HSP) embraces a clinically and genetically heterogeneous group of neurodegenerative diseases characterized by progressive spasticity and weakness of the lower limbs. There currently exist no specific therapies for HSP, and treatment is exclusively symptomatic, aimed at reducing muscle spasticity, and improving strength and gait. The authors set out to perform a comprehensive systematic review of the available scientific literature on the treatment of HSP, applying Cochrane Collaboration methods. The Google Scholar, PubMed and Scopus electronic databases were searched to find relevant randomized control trials (RCTs) and open-label interventional studies, prospective, and retrospective observational studies of supplements, medications, and physical therapy, as well as case reports and case series. Two authors independently analyzed 27 articles selected on the basis of a series of inclusion criteria. Applying a best-evidence synthesis approach, they evaluated these articles for methodological quality. A standardized scoring system was used to obtain interrater assessments. Disagreements were resolved by discussion. The 27 articles focused on pharmacological treatment (n = 17 articles), physical therapy (n = 5), surgical treatment (n = 5). The drugs used in the 17 articles on pharmacological therapy were: gabapentin, progabide, dalfampridine, botulinum toxin, L-Dopa, cholesterol-lowering drugs, betaine, and folinic acid. Gabapentin, progabide, dalfampridine, and botulinum toxin were used as antispastic agents; the study evaluating gabapentin efficacy was well-designed, but failed to demonstrate any significant improvement. L-Dopa, cholesterol-lowering drugs, betaine, and folinic acid were only used in specific HSP subtypes. Two of the three studies evaluating cholesterol-lowering drugs (in SPG5 patients) were well-designed and showed a significant reduction of specific serum biomarkers (oxysterols), but clinical outcomes were not evaluated. The articles focusing on physical treatment and surgical therapy were found to be of low/medium quality and, accordingly, failed to clarify the role of these approaches in HSP. Despite recent advances in understanding of the pathogenesis of HSP and the possibility, in several centers, of obtaining more precise and rapid molecular diagnoses, there is still no adequate evidence base for recommending the various published therapies. Well-designed RCTs are needed to evaluate the efficacy of both symptomatic and pathogenetic treatments.

Should the Gross Motor Function Classification System be used for children who do not have cerebral palsy?

This literature review addressed four questions. (1) In which populations other than cerebral palsy (CP) has the Gross Motor Function Classification System (GMFCS) been applied? (2) In what types of study, and why was it used? (3) How was it modified to facilitate these applications? (4) What justifications and evidence of psychometric adequacy were used to support its application? A search of PubMed, MEDLINE, and Embase databases (January 1997 to April 2017) using the terms: 'GMFCS' OR 'Gross Motor Function Classification System' yielded 2499 articles. 118 met inclusion criteria and reported children/adults with 133 health conditions/clinical descriptions other than CP. Three broad GMFCS applications were observed: as a categorization tool, independent variable, or outcome measure. While the GMFCS is widely used for children with health conditions/clinical description other than CP, researchers rarely provided adequate justification for these uses. We offer recommendations for development/validation of other condition-specific classification systems and discuss the potential need for a generic gross motor function classification system.

WHAT THIS PAPER ADDS

The Gross Motor Function Classification System should not be used outside cerebral palsy or as an outcome measure. The authors provide recommendations for development and validation of condition-specific or generic classification systems.