Neuropathy of metachromatic leukodystrophy: improvement with immunomodulation

Progressive demyelinating polyneuropathy after hematopoietic cell transplantation in metachromatic leukodystrophy: a case series

Metachromatic leukodystrophy (MLD) is a neuro-metabolic disorder due to arylsulfatase A deficiency, causing demyelination of the central and peripheral nervous system. Hematopoietic cell transplantation (HCT) can provide a symptomatic and survival benefit for pre-symptomatic and early symptomatic patients by stabilizing CNS disease. This case series, however, illustrates the occurrence of severely progressive polyneuropathy shortly after HCT in two patients with late-infantile, one with late-juvenile, and one with adult MLD, leading to the inability to walk or sit without support. The patients had demyelinating polyneuropathy before HCT, performed at the ages of 2 years in the first two patients and at 14 and 23 years in the other two patients. The myeloablative conditioning regimen consisted of busulfan, fludarabine and, in one case, rituximab, with anti-thymocyte globulin, cyclosporine, steroids, and/or mycophenolate mofetil for GvHD prophylaxis. Polyneuropathy after HCT progressed parallel with tapering immunosuppression and paralleled bouts of infection and graft-versus-host disease (GvHD). Differential diagnoses included MLD progression, neurological GvHD or another (auto)inflammatory cause. Laboratory, electroneurography and pathology investigations were inconclusive. In two patients, treatment with immunomodulatory drugs led to temporary improvement, but not sustained stabilization of polyneuropathy. One patient showed recovery to pre-HCT functioning, except for a Holmes-like tremor, for which a peripheral origin cannot be excluded. One patient showed marginal response to immunosuppressive treatment and died ten months after HCT due to respiratory failure. The extensive diagnostic and therapeutic attempts highlight the challenge of characterizing and treating progressive polyneuropathy in patients with MLD shortly after HCT. We advise to consider repeat electro-neurography and possibly peripheral nerve biopsy in such patients. Nerve conduction blocks, evidence of the presence of T lymphocytes and macrophages in the neuronal and surrounding nerve tissue, and beneficial effects of immunomodulatory drugs may indicate a partially (auto)immune-mediated pathology. Polyneuropathy may cause major residual disease burden after HCT. MLD patients with progressive polyneuropathy could potentially benefit from a more intensified immunomodulatory drug regime following HCT, especially at times of immune activation.

Myelin oligodendrocyte glycoprotein antibodies in genetic leukodystrophies

Accumulation of intermediate metabolites due to enzyme deficiencies and demyelination can provoke inflammation in genetic leukodystrophies. Thirty patients with genetic leukodystrophy and 48 healthy control sera were tested for anti-myelin oligodendrocyte glycoprotein (MOG) antibodies by fixed and/or live cell-based assays. MOG-IgG was detected in two late infantile metachromatic leukodystrophy (MLD) cases, both of which were also weakly positive for IgG1, and one with IgG3 as the dominant anti-MOG IgG subclass. MOG-IgG was borderline positive in a vanishing white matter (VWM) disease patient. These results suggest that inherited metabolic or degenerative processes can have an autoimmune component, possibly as an epiphenomenon.

Metachromatic Leukodystrophy: Diagnosis, Modeling, and Treatment Approaches

Metachromatic leukodystrophy is a lysosomal storage disease, which is characterized by damage of the myelin sheath that covers most of nerve fibers of the central and peripheral nervous systems. The disease occurs due to a deficiency of the lysosomal enzyme arylsulfatase A (ARSA) or its sphingolipid activator protein B (SapB) and it clinically manifests as progressive motor and cognitive deficiency. ARSA and SapB protein deficiency are caused by mutations in the ARSA and PSAP genes, respectively. The severity of clinical course in metachromatic leukodystrophy is determined by the residual ARSA activity, depending on the type of mutation. Currently, there is no effective treatment for this disease. Clinical cases of bone marrow or cord blood transplantation have been reported, however the therapeutic effectiveness of these methods remains insufficient to prevent aggravation of neurological disorders. Encouraging results have been obtained using gene therapy for delivering the wild-type ARSA gene using vectors based on various serotypes of adeno-associated viruses, as well as using mesenchymal stem cells and combined gene-cell therapy. This review discusses therapeutic strategies for the treatment of metachromatic leukodystrophy, as well as diagnostic methods and modeling of this pathology in animals to evaluate the effectiveness of new therapies.

Peripheral neuropathy in metachromatic leukodystrophy: current status and future perspective

Metachromatic leukodystrophy (MLD) is an autosomal recessively inherited metabolic disease characterized by deficient activity of the lysosomal enzyme arylsulfatase A. Its deficiency results in accumulation of sulfatides in neural and visceral tissues, and causes demyelination of the central and peripheral nervous system. This leads to a broad range of neurological symptoms and eventually premature death. In asymptomatic patients with juvenile and adult MLD, treatment with allogeneic hematopoietic stem cell transplantation (HCT) provides a symptomatic and survival benefit. However, this treatment mainly impacts brain white matter, whereas the peripheral neuropathy shows no or only limited response. Data about the impact of peripheral neuropathy in MLD patients are currently lacking, although in our experience peripheral neuropathy causes significant morbidity due to neuropathic pain, foot deformities and neurogenic bladder disturbances. Besides, the reasons for residual and often progressive peripheral neuropathy after HCT are not fully understood. Preliminary studies suggest that peripheral neuropathy might respond better to gene therapy due to higher enzyme levels achieved than with HCT. However, histopathological and clinical findings also suggest a role of neuroinflammation in the pathology of peripheral neuropathy in MLD. In this literature review, we discuss clinical aspects, pathological findings, distribution of mutations, and treatment approaches in MLD with particular emphasis on peripheral neuropathy. We believe that future therapies need more emphasis on the management of peripheral neuropathy, and additional research is needed to optimize care strategies.

Leukodystrophy presenting as acute-onset polyradiculoneuropathy

BACKGROUND

Sulfatides, the most abundant glycosphingolipids, are a major component of myelin. They are degraded by the combined action of sphingolipid activator protein and arylsulfatase A. Deficiency of either of these entities causes metachromatic leukodystrophy (MLD). On the basis of age of onset, this entity is divided into late infantile, juvenile, and adult subtypes. Late infantile form, the commonest subtype, can exhibit peripheral neuropathy as the initial manifestation. The other two forms usually manifest peripheral neuropathy later in the disease course.

PATIENT

A 1.5-year-old girl with preexisting isolated motor delay presented with acute-onset ascending flaccid quadriparesis, ptosis, and respiratory failure. Ptosis and respiratory failure responded completely to intravenous immunoglobulin, whereas quadriparesis showed minimal improvement. Nerve biopsy revealed metachromatic granules with demyelination, and serum arylsulfatase A levels were undetectable.

CONCLUSION

The severity and nature of the disease coupled with the response to immunotherapy makes this case unusual. This child may represent either an atypical presentation of MLD with coincidental response to immunotherapy or an episode of immune mediated neuropathy in an individual with already diseased nerves due to MLD.

Haematopoietic stem cell transplantation does not retard disease progression in the psycho-cognitive variant of late-onset metachromatic leukodystrophy

Haematopoietic stem cell transplantation has an unproven role in the management of late-onset metachromatic leukodystrophy: theoretically justified through the engraftment of enzyme-replete haematopoietic progenitors and restoration of capacity for sulphatide catabolism in neural tissue through enzyme recapture, the long-term outcome is unknown. The rarity of the psycho-cognitive variant and slow progression of late-onset disease impairs evaluation of treatment. We report detailed clinical and neuropsychological assessments after haematopoietic stem-cell transplantation in a patient with a late-onset psycho-cognitive form of metachromatic leukodystrophy. Cognitive decline, indistinguishable from the natural course of the disease, was serially documented over 11 years despite complete donor chimaerism and correction of leukocyte arylsulphatase A to wild type values; subtle motor deterioration was similarly noted and progressive cerebral volume loss was evident upon magnetic resonance imaging. Sensory nerve conduction deteriorated 17 months post-transplantation with apparent stabilisation at 11-year review. Haematopoietic stem-cell transplantation was ineffective for this rare attenuated variant of metachromatic leukodystrophy. In the few patients identified pre-symptomatically or with early-phase disease, clear recommendations are lacking; when transplantation is considered, umbilical cord blood grafts from enzyme-replete donors with adjunctive mesenchymal stem cell infusions from the same source may be preferable. Improved outcomes will depend on enhanced awareness and early diagnosis of the disease, so that promising interventions such as genetically modified, autologous stem cell transplantation have the best opportunity of success.

Multifocal slowing of nerve conduction in metachromatic leukodystrophy

Polyneuropathy is invariably associated with the late-infantile form of metachromatic leukodystrophy (MLD), and occurs frequently in the early juvenile, juvenile, and adult variants. Uniform slowing of nerve conduction velocity is the neurophysiologic hallmark of metachromatic leukodystrophy and other inherited demyelinating polyneuropathies. To evaluate the consistency of this principle, we reviewed nerve conduction studies in 9 children with late-infantile or early-juvenile metachromatic leukodystrophy. Each child had significant slowing of motor nerve conduction velocity (NCV). The compound muscle action potentials showed abnormal temporal dispersion in 3 of the 9 children, which is usually regarded as the hallmark of acquired demyelinating polyneuropathies. There are reports of multifocal slowing in other hereditary processes including X-linked Charcot-Marie-Tooth disease, hereditary neuropathy with liability to pressure palsies, and adrenomyeloneuropathy. Although multifocal NCV slowing in a child with polyneuropathy is seen most commonly in acquired conditions, a hereditary process, including MLD, cannot always be excluded in this setting.

Early peripheral nervous system manifestations of infantile Krabbe disease

Early infantile Krabbe disease is relatively frequent in the Muslim-Arab population in Israel. It can be easily diagnosed when it presents with the classic clinical picture characterized by central nervous system manifestations of spasticity, irritability, motor regression and seizures associated with a positive family history. We studied eight children diagnosed with Krabbe disease. In two of these children (25%), peripheral neuropathy was the single initial symptom and the only neurologic finding noted for a period of months. In these patients, diagnosis of Krabbe's disease was delayed and established only 9-11 months after the initial symptoms. In two other children with "classical picture" Krabbe disease, areflexia was noted on admission. The occurrence of peripheral neuropathy as an initial symptom in early infantile Krabbe disease may be underestimated. Krabbe disease should be considered in the differential diagnosis of early infantile peripheral neuropathy. Early diagnosis of affected children might be important for genetic counseling for families at risk.

High dose weekly oral prednisone improves strength in boys with Duchenne muscular dystrophy

Daily prednisone improves strength in boys with Duchenne muscular dystrophy, but side effects are almost universal. We used a different dosing regimen of prednisone to determine if benefit to boys with Duchenne muscular dystrophy might be maintained with fewer side effects. Twice weekly oral prednisone was given each Friday and Saturday (5mg/kg/dose). This total dose is twice as high as the daily low dosage prednisone regimen (0.75 mg/kg/day). Twenty boys (8.0+/-1.2 years) were treated. Historical control groups included 18 untreated boys (6.1+/-1.6 years) and four boys (7.3+/-0.6 years) treated with daily prednisone. Strength (using a hand-held manometer and grip meter) and timed functional testing were measured. There was an improvement in upper extremity strength for 95% of boys (n=20) at 6 months using quantitative strength testing. Improvement in lower extremity strength occurred in all boys with antigravity quadriceps strength (17/17). The improvement (P=0.001 for proximal upper extremities; P=0.002 for grip; and P<0.0001 for proximal lower extremities) was significant compared to untreated boys. Sixteen boys were treated continuously for more than 12 months (22+/-1.5 months). Of these, 15 remained significantly stronger than prior to treatment and 8/16 showed additional gains in strength after six months of treatment. Six boys were on the weekly prednisolone 2 years or longer without interruption. All six had upper and lower extremity strength at follow-up that was as good or better than at baseline. Functional testing improved in boys less than 8 years without contractures. Three boys without antigravity quadriceps strength at the start of treatment lost the ability to walk unassisted within 6 months. Eight other boys lost the ability to ambulate unassisted between 12 and 24 months of treatment. In each, progressive contractures developed. Linear growth was maintained in all boys on weekly treatment. Obesity rates did not differ from untreated boys. Twice weekly prednisone improved strength over 6-12 months in the majority of boys, but did not slow contracture development. Sustained benefit beyond 12 months is possible with fewer side effects compared to daily prednisone.

Adult metachromatic leukodystrophy: three cases with normal nerve conduction velocities in a family

Here, we report three cases of late onset metachromatic leukodystrophy (MLD) within a family. The patients presented with psychiatric disturbances and dementia. The arylsulphatase A (ASA) level in leucocytes was zero in all the patients. The cranial magnetic resonance imaging (MRI) revealed bilateral symmetrical demyelination but the nerve conduction velocities were normal in all three cases. The clinical, biochemical, imaging and electrophysiological data of the family has been discussed.

Chronic inflammatory demyelinating polyneuropathy in childhood

Chronic inflammatory demyelinating polyneuropathy (CIDP) in children is relatively rare. However, it has been recognized for many years. In patients presenting with this disease, subacute onset of weakness usually develops over at least 2 months and often progresses to a loss of ambulation. Some children's initial presentations may mimic Guillain-Barré syndrome. Dysasthesias are common. Males are affected more than females, and antecedent illnesses or vaccinations occur in approximately half of patients. Physical examination reveals diffuse, proximal greater than distal weakness, with an absence or depression of muscle stretch reflexes. Electrophysiology confirms demyelination, and spinal fluid examination demonstrates albuminocytologic dissociation. The clinical presentation, diagnosis, and prognosis of childhood CIDP are reviewed. Treatment and immunologic features are also discussed in this article.

Neurophysiology and MRI in late-infantile metachromatic leukodystrophy

We present serial clinical, radiologic, and neurophysiologic findings of a patient with late-infantile metachromatic leukodystrophy who was first admitted at 30 months of age because of gait disturbance. The neurologic findings were consistent with mild spastic diplegia (occasionally with toe walking). Magnetic resonance imaging disclosed diffuse high intensity in the cerebral white matter on T2-weighted images. Nerve conduction velocity studies and evoked-potential studies were markedly abnormal. Assay of arylsulfatase A activity in leukocyte culture disclosed a marked deficiency of the enzyme, confirming the diagnosis of late-infantile metachromatic leukodystrophy. Serial neurophysiologic studies demonstrated a marked decrease of nerve conduction velocities, both motor and sensory, as well as prolongation or disappearance of brainstem auditory-, visual-, and somatosensory-evoked potential latencies. Magnetic resonance imaging studies revealed initially diffuse increased signal intensity of periventricular and subcortical white matter on T2-weighted images, progressing to cortical atrophy with involvement of the arcuate fibers and the cerebellar white matter, correlating with the clinical deterioration (severe spastic tetraplegia with optic atrophy and epilepsy).

Primary alpha-sarcoglycan deficiency responsive to immunosuppression over three years

An 8-year-old girl developed weakness over 2 years and an elevated creatine kinase. The biopsy was most consistent with an active dystrophy with many inflammatory cells present. A trial of immunosuppression was started. In the first 2 months of treatment with prednisone, she had functionally and quantitatively significant improvement in her proximal strength. Over 3 years of treatment she maintained stable strength. Subsequent genetic studies showed that she had primary alpha-sarcoglycan deficiency. The timing and the degree of benefit in strength were similar to that seen in boys with Duchenne muscular dystrophy who are treated with prednisone.

Childhood chronic inflammatory demyelinating polyneuropathy

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a chronic disorder of the peripheral nervous system with sensory and motor involvement, and insidious onset over a period of months. In children and adults, both proximal and distal muscles are affected. Muscle stretch reflexes are absent or depressed. Laboratory findings include elevated cerebrospinal fluid protein with no increase of mononuclear cells. Electrophysiological and pathological studies show evidence of demyelination. No control studies of the efficacy of immunomodulating therapy in childhood CIDP are available. However, several studies have indicated clinical improvement after treatment with prednisolone, plasmapheresis and intravenous immunoglobulin, but disappointing results with other immunosuppressive agents. While some children have a monophasic course, with complete recovery, others have a protracted course, with either a slowly progressive or a relapsing-remitting course, resulting in prolonged morbidity and disability.