Handbook of clinical neurology最新文献

Peripheral nerves are functional networks in the body. Disruption of these networks induces varied functional consequences depending on the types of nerves and organs affected. Despite the advances in microsurgical repair and understanding of nerve regeneration biology, restoring full functions after severe traumatic nerve injuries is still far from achieved. While a blunted growth response from axons and errors in axon guidance due to physical barriers may surface as the major hurdles in repairing nerves, critical additional cellular and molecular aspects challenge the orderly healing of injured nerves. Understanding the systematic reprogramming of injured nerves at the cellular and molecular levels, referred to here as "hallmarks of nerve injury regeneration," will offer better ideas. This chapter discusses the hallmarks of nerve injury and regeneration and critical points of failures in the natural healing process. Potential pharmacological and nonpharmacological intervention points for repairing nerves are also discussed.

Autologous hematopoietic stem cell transplantation (HSCT) is associated with 5-year treatment-free remissions in approximately 80% of patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) who failed or were dependent on intravenous immunoglobulin and or plasmapheresis. Autologous HSCT was associated with significant improvement in strength, independent ambulation, quality of life, nerve conduction velocity, and compound muscle action potential amplitude. The results of HSCT are dependent on proper patient selection, i.e., the right diagnosis and the right stage of the disease. An important caveat is that a significant number of patients with a CIDP diagnostic label are found upon further workup have a peripheral neuropathy of another etiology. Patients undergoing HSCT for CIDP should be reevaluated before HSCT to confirm the diagnosis and those who fail HSCT should be reevaluated for a diagnosis other than CIDP.

Recent advances in neuroimmunology have shed light on the pathogenic mechanisms underlying rare neuroimmunologic conditions such as myasthenia gravis (MG) and stiff person syndrome (SPS). Despite the rarity of these conditions, their complex manifestations and potential for irreversible disability necessitate effective therapeutic strategies. This chapter reviews the current understanding of the safety and efficacy of hematopoietic stem cell transplantation (HSCT) in MG and SPS. Several case reports and retrospective studies have demonstrated promising outcomes following HSCT in refractory MG and SPS, with significant clinical improvement and even discontinuation of chronic immunomodulatory therapy in some cases. Furthermore, HSCT may offer insights into the underlying pathophysiologic mechanisms of these conditions, particularly the role of cellular immunity. Although more research is needed to fully understand the impact of HSCT on disease pathology and outcomes, current evidence suggests that HSCT could be a valuable therapeutic option for patients with refractory MG and SPS.

The health economics of cell and gene therapies is complex; due to resource-intensive manufacturing, high prices are required for commercial viability that are challenging for healthcare systems to accommodate. Despite high prices, cell and gene therapies can provide value when they deliver substantial clinical benefits and displace long-term healthcare costs compared with existing treatment options. In this chapter, the cost utility approach of economic evaluation is discussed, focusing on the considerations that occur more commonly in cell and gene therapies compared to conventional medicines, how these considerations create challenges in interpreting the evidence and coming to conclusions on value, and what tools exist for understanding the level of decision uncertainty. A summary of the economic evaluation of onasemnogene abeparvovec for spinal muscular atrophy is provided as a real-world example that features the considerations discussed.

Neurodegenerative diseases pose a substantial unmet medical need, and no disease-modifying treatments exist. Neurotrophic factors have been studied for decades as a therapy to slow down or stop the progression of these diseases. In this chapter, we focus on Parkinson disease, the second most common neurodegenerative disorder, and on studies carried out with neurotrophic factors. We explore the routes of administration, how the invasive intracranial administration is the challenge, and different ways to deliver the therapeutic proteins, for example, gene therapy and protein therapy. This therapy concept has been developed to mostly work on the restoration of the lost nigrostriatal dopaminergic neuronal connectivity in the brain. However, in recent years, the center of attention of neurotrophic factors has been on maintaining proteostasis and dissolving and preventing protein inclusions called Lewy bodies. We describe the most studied neurotrophic factor families and compare different preclinical experiments that have been carried out. We also analyze several clinical trials and describe their challenges and breakthroughs and discuss the prospects and challenges of neurotrophic support as a therapy for neurodegenerative diseases. In this chapter, we discuss why they still do and why it is essential to continue to work with this area of neurorestorative research around neurotrophic factors.

Amino-acyl tRNA synthetases (ARSs) are enzymes that catalyze the amino-acylation reaction of a specific amino acid and its cognate tRNA and are divided into type 1 (cytosolic) and type 2 (mitochondrial). In this chapter leukodystrophies caused by tRNA synthetase deficiencies are reviewed.

In this chapter, I provide a condensed overview of nine recurring policy and ethical challenges encountered with the development of gene and cell therapies for neurologic disease. These include the question of when to initiate first-in-human trials, the ethics and policy of expanded/special access, the conduct of individualized therapy trials, subject selection in trials, designing trials for negative results, unintended effects of interventions on personal identity, comparator choice in randomized trials, consent and therapeutic misestimation, and cost and access for effective therapies. Broadly speaking, I argue that early in their development, the justification of risk in trials of gene and cell therapies derives from the social and scientific value of a trial and not the therapeutic value for trial participation. This generates strong imperatives to justify, design, and report trials appropriately and select patient populations that incur the least burden and opportunity cost for trial participation. Late in intervention development, policy makers must contend with the fact that proven effective interventions will almost certainly amplify strains in healthcare budgets as well as the ethical justifications standing behind reimbursement decisions.

Intracranial calcification (ICC) occurs in many neurologic disorders both acquired and genetic. In some inherited white matter disorders, it is a common or even invariable feature where the presence and pattern of calcification provides an important pointer to the specific diagnosis. This is particularly the case for the Aicardi-Goutières syndrome (AGS) and for Coats plus (CP) and leukoencephalopathy with calcifications and cysts (LCC), which are discussed in detail in this chapter. AGS is a genetic disorder of type 1 interferon regulation, caused by mutations in any of the nine genes identified to date. In its classic form, AGS has very characteristic clinical and neuroimaging features which will be discussed here. LCC is a purely neurologic disorder caused by mutations in the SNORD118 gene, whereas CP is a multisystem disorder of telomere function that may result from mutations in the CTC1, POT1, or STN genes. In spite of the different pathogenetic basis for LCC and CP, they share remarkably similar neuroimaging and neuropathologic features. Cockayne syndrome, in which ICC is usually present, is discussed elsewhere in this volume. ICC may occur as an occasional feature of many other white matter diseases, including Alexander disease, Krabbe disease, X-ALD, and occulodentodigital dysplasia.

Magnetic resonance imaging (MRI) pattern recognition is a powerful tool for quick diagnosis of genetic and acquired white matter disorders. In many cases, distribution and character of white matter abnormalities directly point to a specific diagnosis and guide confirmatory testing. Knowledge of normal brain development is essential to interpret white matter changes in young children. MRI is also used for disease staging and treatment decisions in leukodystrophies and acquired disorders as multiple sclerosis, and as a biomarker to follow treatment effects.

More than 50 leukodystrophies have been described. This group of inherited disorders affects myelin development and/or maintenance and can manifest from birth to adulthood. Neuroinflammation is a hallmark of some leukodystrophies, explaining in part the therapeutic benefit of hematopoietic stem cell transplantation (HSCT). Indeed, in addition to supplying the CNS with myelomonocyte donor cells expressing the deficient protein or enzyme, HSCT allows the restoration of normal microglia function, which may act on neuroinflammation. In this chapter, we explore the rationale, indication, and outcome of HSCT in Cerebral Adrenoleukodystrophy (CALD), Metachromatic Leukodystrophy (MLD), Krabbe Disease (KD), and Adult-onset Leukoencephalopathy with Axonal Spheroids and Pigmented Glia (ALSP), which are among the most frequent leukodystrophies. For these leukodystrophies, HSCT may modify notably the natural history and improve CNS-related deficits, provided that the procedure is performed early into the disease course. In addition, we discuss the recent development of ex vivo gene therapy for CALD and MLD as a promising alternative to allograft.