Long-term efficacy and safety of inotersen in patients with hereditary transthyretin amyloid polyneuropathy with or without cardiomyopathy: post hoc analysis of NEURO-TTR open-label extension

Background/Introduction

Cardiomyopathy (CM) with associated heart failure and polyneuropathy (PN) are common manifestations of hereditary transthyretin amyloidosis (ATTRv), a progressive, debilitating, and fatal disease that results from the deposition of misfolded transthyretin (TTR) protein throughout the body. NEURO-TTR (NCT01737398) showed that inotersen, an antisense oligonucleotide inhibitor of TTR protein production, slowed the progression of PN and maintained quality of life in patients with ATTRv.

Purpose

To report efficacy and safety from the open-label extension (OLE) of the NEURO-TTR study in patients with ATTRv PN overall and in CM subgroups.

Methods

Patients who completed NEURO-TTR, enrolled in the OLE (NCT02175004), and either switched from placebo in NEURO-TTR to inotersen in the OLE (placebo-inotersen) or received inotersen in NEURO-TTR and remained on inotersen in the OLE (inotersen-inotersen) were included. Assessments included the modified Neuropathy Impairment Score +7 composite score (mNIS+7 [range –22.3 to 346.3], a measure of neuropathy with higher scores indicative of poorer function), TTR levels, and safety monitoring. Utilizing patients from Europe and North America (EU+NA) as of 28 July 2020, this post hoc analysis examined two subgroups: CM ECHO and severe CM ECHO. CM was defined as a diagnosis of ATTRv CM at study entry or all of the following criteria: a left ventricular wall thickness of ≥1.3 cm on transthoracic echocardiography at baseline, no known history of persistent hypertension (systolic blood pressure ≥150 mm Hg) within 12 months before study screening, and evaluable baseline ECHO obtained by central assessment. Severe CM was defined as an interventricular septum thickness ≥1.5 cm at baseline. Descriptive statistics are reported.

Results

In the overall population and both CM subgroups, the placebo-inotersen group demonstrated slowing of neurological disease progression compared with natural history based on NEURO-TTR placebo projection (estimated natural history will be presented). Furthermore, in the overall population and both CM subgroups, the inotersen-inotersen group demonstrated sustained benefit compared with the placebo-inotersen group (Table). Change in serum TTR levels will be presented. There have been no reports of grade 4 thrombocytopenia or acute glomerulonephritis under enhanced monitoring in patients in the EU+NA despite the increased duration of exposure. No new safety concerns were identified.

Conclusions

Inotersen treatment for >3 years slowed the progression of PN associated with ATTRv in patients with CM, including severe CM. In both subgroups, greater neurological preservation was observed in those who initiated inotersen earlier (inotersen-inotersen group), underscoring the benefits of early treatment. No new safety signals were detected in this OLE analysis; enhanced monitoring is successful in managing the risk for thrombocytopenia and acute glomerulonephritis.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): This study was sponsored by Akcea Therapeutics, an affiliate of Ionis Pharmaceuticals, Inc.

Early data on long-term efficacy and safety of inotersen in patients with hereditary transthyretin amyloidosis: a 2-year update from the open-label extension of the NEURO-TTR trial

BACKGROUND AND PURPOSE

Hereditary transthyretin (hATTR) amyloidosis causes progressive polyneuropathy resulting from transthyretin (TTR) amyloid deposition throughout the body, including the peripheral nerves. The efficacy and safety of inotersen, an antisense oligonucleotide inhibitor of TTR protein production, were demonstrated in the pivotal NEURO-TTR study in patients with hATTR polyneuropathy. Here, the long-term efficacy and safety of inotersen are assessed in an ongoing open-label extension (OLE) study.

METHODS

Patients who completed NEURO-TTR were eligible to enroll in the OLE (NCT02175004). Efficacy assessments included the modified Neuropathy Impairment Score plus seven neurophysiological tests composite score (mNIS + 7), the Norfolk Quality of Life - Diabetic Neuropathy (Norfolk QOL-DN) questionnaire total score and the Short-Form 36 Health Survey (SF-36) Physical Component Summary (PCS) score. Safety and tolerability were also assessed.

RESULTS

Overall, 97% (135/139) of patients who completed NEURO-TTR enrolled in the OLE. Patients who received inotersen for 39 cumulative months in NEURO-TTR and the OLE continued to show benefit; patients who switched from placebo to inotersen in the OLE demonstrated improvement or stabilization of neurological disease progression by mNIS + 7, Norfolk QOL-DN and SF-36 PCS. No new safety concerns were identified. There was no evidence of increased risk for grade 4 thrombocytopenia or severe renal events with increased duration of inotersen exposure.

CONCLUSION

Inotersen slowed disease progression and reduced deterioration of quality of life in patients with hATTR polyneuropathy. Early treatment with inotersen resulted in greater long-term disease stabilization than delayed initiation. Routine platelet and renal safety monitoring were effective; no new safety signals were observed.

Does prediabetes cause small fiber sensory polyneuropathy? Does it matter?

BACKGROUND AND OBJECTIVES

The association between prediabetes and distal polyneuropathy (DPN) remains controversial. Here we test whether the prevalence of small fiber sensory distal polyneuropathy is increased in prediabetes.

METHODS

Prospectively recruited cohorts of healthy subjects and those with prediabetes from Olmsted County, Minnesota, were assessed for positive neuropathic sensory symptoms, or pain symptoms characteristic of small fiber sensory DPN. Hyperalgesia and hypoalgesia were assessed by "smart" quantitative sensation testing (QST). The prevalence of symptoms and QST abnormalities were compared among the groups.

RESULTS

There was no significant increase in the prevalence of positive neuropathic sensory or pain symptoms, nor of hyper- or hypoalgesia in the prediabetes group. There was an increased prevalence of hypoalgesia of the foot only in newly diagnosed diabetes.

CONCLUSIONS

Based on positive sensory and pain symptoms and QSTs, we did not find an increase in small fiber sensory DPN in prediabetes. Recognizing that obesity and diabetes mellitus are implicated in macro- and microvessel complications, physicians should encourage healthy living and weight loss in patients with prediabetes. In medical practice, alternate causes should be excluded before concluding that small fiber sensory distal neuropathy is secondary to prediabetes.

Autonomic dysfunction in chronic inflammatory demyelinating polyradiculoneuropathy

OBJECTIVES

Autonomic deficits in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) have not been adequately quantitated. The Composite Autonomic Severity Score (CASS) is a validated instrument for laboratory quantitation of autonomic failure derived from standard autonomic reflex tests. We characterized dysautonomia in CIDP using CASS.

METHODS

Autonomic function was retrospectively analyzed in 47 patients meeting CIDP criteria. CASS ranges from 0 (normal) to 10 (pandysautonomia), reflecting summation of sudomotor (0-3), cardiovagal (0-3), and adrenergic (0-4) subscores. Severity of neurologic deficits was measured with Neuropathy Impairment Score (NIS). Degree of small fiber involvement was assessed with quantitative sensation testing. Thermoregulatory sweat test (TST) was available in 8 patients.

RESULTS

Patients (25 men) were middle-aged (45.0 ± 14.9 years) with longstanding CIDP (3.5 ± 4.3 years) of moderate severity (NIS, 46.5 ± 32.7). Autonomic symptoms were uncommon, mainly gastrointestinal (9/47; 19%) and genitourinary (8/47; 17%). Autonomic deficits (CASS ≥1) were frequent (22/47; 47%) but very mild (CASS, 0.8 ± 0.9; CASS ≤3, all cases). Deficits were predominantly sudomotor (16/47; 34%) and cardiovagal (10/47; 21%) with relative adrenergic sparing (4/47; 9%). TST was abnormal in 5 of 8 patients (anhidrosis range, 2%-59%). Sudomotor impairment was predominantly distal and postganglionic. Somatic deficits (disease duration, severity, small fiber deficits) did not predict presence of autonomic deficits.

CONCLUSION

Our data characterize the autonomic involvement in classic CIDP as mild, cholinergic, and predominantly sudomotor mainly as a result of lesions at the distal postganglionic axon. Extensive or severe autonomic involvement (CASS ≥4) in suspected CIDP should raise concern for an alternative diagnosis.

TRPV4 mutations and cytotoxic hypercalcemia in axonal Charcot-Marie-Tooth neuropathies

OBJECTIVE

To improve understanding of TRPV4-associated axonal Charcot-Marie-Tooth (CMT) neuropathy phenotypes and their debated pathologic mechanism.

METHODS

A total of 17 CMT2C phenotypic families with vocal cord and diaphragmatic involvement and 36 clinically undifferentiated CMT2 subjects underwent sequencing analysis of the coding region of TRPV4. Functional studies of mutant proteins were performed using transiently transfected cells for TRPV4 subcellular localization, basal and stimulated Ca(2+) channel analysis, and cell viability assay with or without channel blockade.

RESULTS

Two TRPV4 mutations R232C and R316H from 17 CMT2C families were identified in the ankyrin repeat domains. The R316H is a novel de novo mutation found in a patient with CMT2C phenotype. The family with R232C mutation had individuals with and without vocal cord and diaphragm involvement. Both mutant TRPV4 proteins had normal subcellular localization in HEK293 and HeLa cells. Cells transfected with R232C and R316H displayed increased intracellular Ca(2+) levels and reversible cell death by the TRPV channel antagonist, ruthenium red.

CONCLUSION

TRPV4 ankyrin domain alterations including a novel de novo mutation cause axonal CMT2. Individuals with the same mutation may have nondistinct CMT2 or have phenotypic CMT2C with vocal cord paresis. Reversible hypercalcemic gain-of-function of mutant TRPV4 instead of loss-of-function appears to be pathologically important. The reversibility of cell death by channel blockade provides an attractive area of investigation in consideration of treatable axonal degeneration.

Incidence and prevalence of CIDP and the association of diabetes mellitus

BACKGROUND

The reported prevalence of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) varies greatly, from 1.9 to 7.7 per 100,000. CIDP is reported to occur more commonly in patients with diabetes mellitus (DM) but has not been rigorously tested.

OBJECTIVES

To determine the incidence (1982-2001) and prevalence (on January 1, 2000) of CIDP in Olmsted County, Minnesota, and whether DM is more frequent in CIDP.

METHODS

CIDP was diagnosed by clinical criteria followed by review of electrophysiology. Cases were coded as definite, probable, or possible. DM was ascertained by clinical diagnosis or current American Diabetes Association glycemia criteria.

RESULTS

One thousand five hundred eighty-one medical records were reviewed, and 23 patients (10 women and 13 men) were identified as having CIDP (19 definite and 4 probable). The median age was 58 years (range 4-83 years), with a median disease duration at diagnosis of 10 months (range 2-64 months). The incidence of CIDP was 1.6/100,000/year. The prevalence was 8.9/100,000 persons on January 1, 2000. Only 1 of the 23 CIDP patients (4%) also had DM, whereas 14 of 115 age- and sex-matched controls (12%) had DM.

CONCLUSIONS

1) The incidence (1.6/100,000/year) and prevalence (8.9/100,000) of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) are similar to or higher than previous estimates. 2) The incidence of CIDP is similar to that of acute inflammatory demyelinating polyradiculoneuropathy within the same population. 3) Diabetes mellitus (DM) is unlikely to be a major risk covariate for CIDP, but we cannot exclude a small effect. 4) The perceived association of DM with CIDP may be due to misclassification of other forms of diabetic neuropathies and excessive emphasis on electrophysiologic criteria.

Defining the pathophysiology of the paclitaxel-acute pain syndrome

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Background: Paclitaxel therapy often results in a unique sub-acute pain syndrome, whose pathophysiology is unknown. While this syndrome is often termed as a ‘myalgia’ or ‘arthralgia’, it has not been demonstrated to be associated with any structural injury of muscles or joints. Identifying the pathophysiology mechanisms that result in the paclitaxel-acute pain syndrome might be a positive step in the development of effective prevention and/or treatment strategies. With the hypothesis that the paclitaxel-acute pain syndrome occurs as a result of nerve injury, an observational study to clarify the clinical characteristics of this syndrome was initiated. Methods: Oncology patients who were treated with at least one dose of paclitaxel and reported developing sub-acute pain were questioned using a detailed structured interview. Various aspects of the pain, including the time of onset, duration, location, severity, and exacerbating factors were evaluated. Data were tabulated descriptively. Results: Eighteen patients were interviewed. The onset of pain typically occurred 1–2 days after therapy and lasted for a median of 4–5 days. Pain was most commonly located in the back, hips, shoulders, thighs, legs and feet, with the most common descriptors used being ‘aching’ or ‘deep pain’. Commonly used adjectives to describe the pain were: ‘radiating’, ‘shooting’, ‘aching’, ‘stabbing’ and ‘pulsating’. Some patients described increased pain with weight bearing or walking. Fifteen of 18 patients specifically denied localization of pain to either joints or muscles. Conclusions: The nature of the pain, i.e. , generalized, deep aching pain, the notation of increased sensitivity with weight bearing (mechanical hyperalgesia) and the lack of localization to joints or muscles, support the hypothesis that the paclitaxel-acute pain syndrome results from a hyperalgesic dysfunction of nociceptive receptors, their fibers, or the spinothalamic system. These clinical conclusions are supported by the recent findings that markers of cellular injury can be identified in peripheral nerve tissues shortly following paclitaxel administration in an animal model (Peters CM, et al., Exp Neurol. 2007 Jan;203(1):42- 54).

No significant financial relationships to disclose.

Polyneuropathy dysfunction scores

Three polyneuropathy scores are described, which seem to be valid and sensible measures to score dysfunction and disability in patients with generalised motor neuropathies

Myelin protein zero mutation His39Pro: hereditary motor and sensory neuropathy with variable onset, hearing loss, restless legs and multiple sclerosis

BACKGROUND

Mutations of myelin protein zero (MPZ) may cause inherited neuropathy with variable expression.

OBJECTIVE

To report phenotypic variability in a large American kindred with MPZ mutation His39Pro.

PATIENTS

Genetic testing was performed on 77 family members and 200 controls. Clinical and electrophysiological field study assessments were available for review in 47 family members.

RESULTS

His39Pro was found in all 10 individuals prospectively identified with neuropathy. 200 normal controls were without mutation. Symptoms of neuropathy began in adulthood and were slowly progressive except for one acute-onset painful sensory neuropathy. Associated features included premature hearing loss (n = 7), nocturnal restless leg symptoms (n = 8) and multiple sclerosis in one.

CONCLUSIONS

MPZ mutation His39Pro may be associated with acute-onset neuropathy, early-onset hearing loss and restless legs. The relationship with multiple sclerosis in the proband remains uncertain.

The natural history and long-term outcome of 57 limb sarcoidosis neuropathy cases

Fifty-seven patients with biopsy-proven sarcoidosis causing limb neuropathy were reviewed in order to delineate the characteristic symptoms, impairments, disability, course, outcome and response to corticosteroid treatment of limb sarcoid neuropathy. Typically the neuropathy had a definite date of symptomatic onset. Prominent were positive neuropathic sensory symptoms (P-NSS), especially pain, overshadowing weakness and sensory loss. P-NSS were the main cause of disability. Almost always the pattern was asymmetric and not length-dependent (unlike distal polyneuropathy). We inferred (from kind and distribution of symptoms, signs and electrophysiologic and other test results) that the pathologic process was focal or multifocal, involving most classes of nerve fibers and variable levels of proximal to distal levels of roots and peripheral nerves. Additional features aiding in diagnosis were: systemic symptoms such as fatigue, malaise, arthralgia, fever and weight loss; involvement of multiple tissues (i.e. skin, lymph nodes and eye); the patterns of neuropathy; MRI features; and ultimately tissue diagnosis. Axonal degeneration predominated, although an acquired demyelinating process was observed in 3 patients. For most cases, the disease had a chronic, monophasic course. MRI studies done in later years of affected neural structures were helpful in identifying leptomeningeal thickening, hilar adenopathy; and enlargement and T2 enhancement of nerve roots, plexuses, and limb nerves. Corticosteroid treatment appeared to ameliorate symptoms more than impairments. Several variables were associated with neuropathic improvement: CSF pleocytosis, short duration between symptom onset and treatment, and a higher grade of disability at first evaluation-a possible rationale for future earlier diagnosis and treatment.

SPTLC1 and RAB7 mutation analysis in dominantly inherited and idiopathic sensory neuropathies

BACKGROUND

The variable clinical features of hereditary sensory and autonomic neuropathy (HSAN I) suggest heterogeneity. Some cases of idiopathic sensory neuropathy could be caused by missense mutations of SPTLC1 and RAB7 and not be recognised as familial.

OBJECTIVE

To screen persons with dominantly inherited HSAN I and others with idiopathic sensory neuropathies for known mutations of SPTLC1 and RAB7.

PATIENTS

DNA was examined from well characterised individuals of 25 kindreds with adult onset HSAN I for mutations of SPTLC1 and RAB7; 92 patients with idiopathic sensory neuropathy were also screened for known mutations of these genes.

RESULTS

Of the 25 kindreds, only one had a mutation (SPTLC1 399T-->G). This kindred, and 10 without identified mutations, had prominent mutilating foot injuries with peroneal weakness. Of the remainder, 12 had foot insensitivity with injuries but no weakness, one had restless legs and burning feet, and one had dementia with hearing loss. No mutation of RAB7 was found in any of these. No known mutations of SPTLC1 or RAB7 were found in cases of idiopathic sensory neuropathy.

CONCLUSIONS

Adult onset HSAN I is clinically and genetically heterogeneous and further work is required to identify additional genetic causes. Known SPTLC1or RAB7 mutations were not found in idiopathic sensory neuropathy.

Sudden cardiac death in diabetes mellitus: risk factors in the Rochester diabetic neuropathy study

OBJECTIVES

To determine risk factors for sudden cardiac death and the role of diabetic autonomic neuropathy (DAN) in the Rochester diabetic neuropathy study (RDNS).

METHODS

Associations between diabetic and cardiovascular complications, including DAN, and the risk of sudden cardiac death were studied among 462 diabetic patients (151 type 1) enrolled in the RDNS. Medical records, death certificates, and necropsy reports were assessed for causes of sudden cardiac death.

RESULTS

21 cases of sudden cardiac death were identified over 15 years of follow up. In bivariate analysis of risk covariates, the following were significant: ECG 1 (evolving and previous myocardial infarctions): hazard ratio (HR) = 4.4 (95% confidence interval (CI), 1.6 to 12.1), p = 0.004; ECG 2 (bundle branch block or pacing): HR = 8.6 (2.9 to 25.4), p<0.001; ECG 1 or ECG 2: HR = 4.2 (1.3 to 13.4), p = 0.014; and nephropathy stage: HR = 2.1 (1.3 to 3.4), p = 0.002. Adjusting for ECG 1 or ECG 2, autonomic scores, QTc interval, high density lipoprotein (HDL) cholesterol, 24 hour microalbuminuria, and 24 hour total proteinuria were significant. However, adjusting for nephropathy, none of the autonomic indices, QTc interval, HDL cholesterol, microalbuminuria, or total proteinuria was significant. At necropsy, all patients with sudden cardiac death had coronary artery or myocardial disease.

CONCLUSIONS

Sudden cardiac death was correlated with atherosclerotic heart disease and nephropathy, and to a lesser degree with DAN and HDL cholesterol. Although DAN is associated with sudden cardiac death, it is unlikely to be its primary cause.

The gene for HMSN2C maps to 12q23-24: a region of neuromuscular disorders

BACKGROUND

Hereditary motor and sensory neuropathy type 2C (HMSN2C, Charcot-Marie-Tooth 2C [CMT2C]) is an autosomal dominant motor and sensory neuropathy involving limb, diaphragm, vocal cord, and intercostal muscles.

OBJECTIVE

To identify the chromosome localization for this disorder in one large American family of English and Scottish ethnicity.

METHODS

Variable clinical severity led the authors to combine several approaches to accurately identify affected patients. Genome-wide two-point linkage analysis, high-definition mapping, and multipoint and recombinant haplotype analyses were performed. Mutation analysis of the triplet repeat region of ataxin-2 was also carried out.

RESULTS

The initial genome-wide scan identified a region at 12q24, and fine mapping provided a maximal lod score of 4.73 (D12S1645 and D12S1583 at theta = 0.01 and 0, respectively). With multipoint analysis, a higher lod score of 5.17 was obtained and localized to the same region at 119.0 cM. Haplotype analysis narrowed the region to approximately 5.0 cM between D12S1646,D12S1330 and D12S105,D12S1339 (12q23.3-24.21). Ataxin-2, the gene responsible for spinocerebellar ataxia type 2 (SCA2), localizes to this region, but no triplet repeat expansion or point mutations within the repeat were found.

CONCLUSIONS

The gene for HMSN2C maps to 12q23-24. This region is associated with SCA2, scapuloperoneal spinal muscular atrophy, and congenital distal spinal muscular atrophy. Further studies are needed to demonstrate the specific gene alteration and its relationship with nearby genes.

Inflammation and neuropathic attacks in hereditary brachial plexus neuropathy

OBJECTIVE

To study the role of mechanical, infectious, and inflammatory factors inducing neuropathic attacks in hereditary brachial plexus neuropathy (HBPN), an autosomal dominant disorder characterised by attacks of pain and weakness, atrophy, and sensory alterations of the shoulder girdle and upper limb muscles.

METHODS

Four patients from separate kindreds with HBPN were evaluated. Upper extremity nerve biopsies were obtained during attacks from a person of each kindred. In situ hybridisation for common viruses in nerve tissue and genetic testing for a hereditary tendency to pressure palsies (HNPP; tomaculous neuropathy) were undertaken. Two patients treated with intravenous methyl prednisolone had serial clinical and electrophysiological examinations. One patient was followed prospectively through pregnancy and during the development of a stereotypic attack after elective caesarean delivery.

RESULTS

Upper extremity nerve biopsies in two patients showed prominent perivascular inflammatory infiltrates with vessel wall disruption. Nerve in situ hybridisation for viruses was negative. There were no tomaculous nerve changes. In two patients intravenous methyl prednisolone ameliorated symptoms (largely pain), but with tapering of steroid dose, signs and symptoms worsened. Elective caesarean delivery did not prevent a typical postpartum attack.

CONCLUSIONS

Inflammation, probably immune, appears pathogenic for some if not all attacks of HBPN. Immune modulation may be useful in preventing or reducing the neuropathic attacks, although controlled trials are needed to establish efficacy, as correction of the mutant gene is still not possible. The genes involved in immune regulation may be candidates for causing HBPN disorders.

Increased weakness after pancreas and kidney transplantation

BACKGROUND

Already there is evidence that simultaneous pancreas and kidney (SPK), or pancreas after kidney (PAK) transplantation, in patients with type 1 diabetes mellitus and end-stage kidney disease prevents worsening of diabetic polyneuropathy, but neuropathic improvement is delayed and incomplete.

METHODS

In 85 patients with type 1 diabetes mellitus who underwent SPK or PAK transplantations, we performed sequential neuromuscular evaluations before, every 3 months after, and yearly after transplantation, quantitating muscle weakness separately from overall severity of polyneuropathy.

RESULTS

We found that, on average, the weakness subscore of the Neuropathy Impairment Score of the lower limbs [NIS(LL)-W] was significantly worse at 3, 6, 9, and 12 months (by about 5 points) than at baseline. By contrast, for these times after transplantation, a composite score of nerve conduction abnormalities, an independent measure of severity of polyneuropathy, was not significantly worse and, in fact, was significantly improved. In multivariate analysis, length of hospital stay correlated with the increased weakness.

CONCLUSIONS

We conclude that: (1) increased neuromuscular impairment after transplantation is mainly due to muscle weakness and not to worsening polyneuropathy; (2) in multivariate analysis, duration of hospitalization after transplantation was significantly associated with this increased weakness; (3) increased weakness is probably due to development of myopathy, which may be related to graft rejection, immunosuppression, sepsis, and intercurrent infections; (4) in future transplantation trials, weakness should be evaluated separately from neuropathic status, and the lowest efficacious dosages of immunotherapy should be used; and (5) essentially all diabetic patients reported that SPK or PAK transplantation was worthwhile because it freed them from diabetic lifestyle concerns.

Diagnostic accuracy and certainty from sequential evaluations in peripheral neuropathy

Three masked neuromuscular experts analyzed the contribution of the data from sequential evaluations in predicting specific varieties of peripheral neuropathy in 72 patients. The largest improvement (16%) in diagnostic accuracy resulted from presentation of neurologic history. By contrast, diagnostic confidence increased gradually with presentation of additional medical information. Therefore, the authors conclude that for diagnostic accuracy and certainty, expert neuromuscular judgment and extensive characterizing or discriminative testing are needed.

Methylprednisolone may improve lumbosacral radiculoplexus neuropathy

OBJECTIVE

To report on an open trial of intravenous methylprednisolone (IV MP) in nondiabetic lumbosacral radiculoplexus neuropathy (LSRPN).

BACKGROUND

Lumbosacral radiculoplexus neuropathy is a subacute, unilateral or asymmetric syndrome of pain, weakness, and paresthesia of the lower extremity, which is attributed to ischemic injury from microvasculitis in lumbosacral roots, plexus, and nerves.

METHODS

Eleven nondiabetic patients with worsening LSRPN were treated - ten with infusions of IV MP (1 gm/wk) for 8 to 16 weeks and one with an equivalent dosage of oral prednisone. The main endpoints evaluated were: 1) the Neuropathy Impairment Score (NIS), and 2) the Neuropathy Symptoms and Change (NSC) scores.

RESULTS

The median age of our patients was 67 years, range 49 to 86 years. Seven patients were women. All 11 patients reported improvement during treatment--nine reported marked improvement. The median NIS improved from 42 points (range 9 to 106 points) before treatment, to 20 points (range 5 to 57 points) (p = 0.005) after treatment. Pain was completely resolved in four patients and much improved in seven. The change subscore and the severity subscore of the NSC were statistically significantly improved after treatment. Prior to treatment, all patients had significant weakness with six confined to wheelchairs and four using mechanical devices to aid in ambulation. After treatment, the weakness was markedly improved in nine patients; only one still required a wheelchair and six walked independently (p = 0.03).

CONCLUSIONS

1) In LSRPN, pain and neurological deficits improved (often dramatically) with IV MP treatment. 2) Although our results should be interpreted with caution since this trial is uncontrolled, IV MP may favorably affect the natural history of LSRPN. 3) The results are sufficiently promising to provide a rationale for prospective, sham controlled, double blind trials.

Non-diabetic lumbosacral radiculoplexus neuropathy: Natural history, outcome and comparison with the diabetic variety

Diabetic lumbosacral radiculoplexus neuropathy (DLSRPN) (other names include diabetic amyotrophy) is well recognized, unlike the non-diabetic lumbosacral radiculoplexus neuropathy (LSRPN), which has received less attention. Our objective was to characterize the natural history and outcome of LSRPN and to assess whether it is similar to the diabetic variety in its symptoms, course, electrophysiological features, quantitative sensory and autonomic findings, and the underlying pathophysiology. We studied 57 patients with LSRPN and 33 patients with DLSRPN. We found that the age of onset, course, kind and distribution of symptoms and impairments, laboratory findings and outcomes are essentially alike. Both disorders are a lumbosacral plexus neuropathy associated with weight loss, often beginning focally or asymmetrically in the thigh or leg but usually progressing to involve the initially unaffected segment and the contralateral side. Both have prolonged morbidity due to pain, paralysis, autonomic involvement and sensory loss. In biopsied distal LSRPN nerves, we found changes similar to those found in DLSRPN-alterations typical of ischaemic injury and of microvasculitis. The long-term outcome was determined in 42 LSRPN patients: two had become diabetic, seven had relapsed and only three had recovered completely, although all had improved. We conclude that: (i) LSRPN is a subacute, asymmetrical, painful and debilitating neuropathy of the lower limbs associated with weight loss, and we think it is under-recognized; (ii) recovery from the long-term impairments of LSRPN is usually delayed and incomplete and only a small minority of patients develop diabetes mellitus; (iii) LSRPN mirrors the diabetic variety in its clinical features, course, pathological findings (ischaemic injury from microvasculitis) and long-term outcome; and (iv) LSRPN should be set apart from chronic inflammatory demyelinating polyradiculoneuropathy and from systemic necrotizing vasculitis. We infer an autoimmune basis for LSRPN and emphasize the need for controlled trials of immune-modulating therapy.

Probable adult polyglucosan body disease

Adult polyglucosan body disease is a clinicopathologic entity characterized by progressive upper and lower motor neuron dysfunction, sensory loss in the lower extremities, sphincter dysfunction, and occasionally dementia. Pathologically, numerous large polyglucosan bodies are noted in peripheral nerves, cerebral hemispheres, and the spinal cord, as well as in other systemic tissues. We present a case of probable adult polyglucosan body disease based on clinical history and examination, magnetic resonance images, and sural nerve biopsy findings.

Efficacy and safety of recombinant human nerve growth factor in patients with diabetic polyneuropathy: A randomized controlled trial. rhNGF Clinical Investigator Group

CONTEXT

Nerve growth factor is a neurotrophic factor that promotes the survival of small fiber sensory neurons and sympathetic neurons in the peripheral nervous system. Recombinant human nerve growth factor (rhNGF) has demonstrated efficacy as treatment for peripheral neuropathy in experimental models and phase 2 clinical trials.

OBJECTIVE

To evaluate the efficacy and safety of a 12-month regimen of rhNGF in patients with diabetic polyneuropathy.

DESIGN

Randomized, double-blind, placebo-controlled phase 3 trial conducted from July 1997 through May 1999.

SETTING

Eighty-four outpatient centers throughout the United States.

PATIENTS

A total of 1019 men and women aged 18 to 74 years with either type 1 or type 2 diabetes and a sensory polyneuropathy attributable to diabetes.

INTERVENTIONS

Patients were randomly assigned to receive either rhNGF, 0.1 microg/kg (n = 504), or placebo (n = 515) by subcutaneous injection 3 times per week for 48 weeks. Patients were assessed at baseline, 12 weeks, 24 weeks, and 48 weeks.

MAIN OUTCOME MEASURES

The primary outcome measure was a change in neuropathy between baseline and week 48, demonstrated by the Neuropathy Impairment Score for the Lower Limbs, compared between the 2 groups. Secondary outcome measures included quantitative sensory tests using the CASE IV System, the Neuropathy Symptom and Change questionnaire, the Patient Benefit Questionnaire (PBQ), and a global symptom assessment, as well as nerve conduction studies and occurrence of new plantar foot ulcers. Patients also were evaluated for presence of adverse events.

RESULTS

Among patients who received rhNGF, 418 (83%) completed the regimen compared with 461 (90%) who received placebo. Administration of rhNGF was safe, with few adverse events attributed to treatment apart from injection site pain/hyperalgesia and other pain syndromes. However, neither the primary end point (P =.25) nor most of the secondary end points demonstrated a significant benefit of rhNGF. Exceptions were the global symptom assessment (P =.03) and 2 of 32 comparisons within the PBQ, which showed a modest but significant benefit of rhNGF (P =.05 for severity of pain in the legs and P =.003 for 6-month symptoms in the feet and legs).

CONCLUSION

Unlike previous phase 2 trials, this phase 3 clinical trial failed to demonstrate a significant beneficial effect of rhNGF on diabetic polyneuropathy. JAMA. 2000;284:2215-2221.

Complement activation in acquired and hereditary amyloid neuropathy

The pathogenesis of the axonal degeneration in acquired or hereditary amyloidosis is unknown. In this immunohistochemistry study, we examined 20 sural nerve biopsies from individuals with amyloid neuropathy (14 acquired and 6 hereditary) for evidence of complement activation. Complement activation products were detected on and around amyloid deposits within peripheral nerves. We found no difference in the extent, location or pattern of complement activation products between the 2 forms of amyloidosis. The presence of early classical pathway activation markers in the absence of antibody in hereditary cases suggests an antibody-independent activation of the classical pathway through binding of C1q. The lack of Factor Bb-suggested alternative pathway activation was not significant in these cases. The detection of C5b-9 neoantigen on amyloid deposits demonstrated that the full complement cascade was activated. Complement activation on amyloid deposits and the generation of C5b-9 in vivo may contribute to bystander injury of axons in the vicinity of amyloid deposits.

Fulminant case of hereditary neuropathy with liability to pressure palsy

Hereditary neuropathy with liability to pressure palsy (HNPP) is typified as isolated nerve palsies caused by trivial compression or trauma. It rarely presents in two extremities and even more infrequently affects all four limbs simultaneously. We present a patient who concurrently experienced right shoulder, left hand, and bilateral foot weakness mimicking several multifocal conditions. Electromyography suggested HNPP and subsequent nerve biopsy and genetic testing were confirmatory. The case demonstrates that HNPP can present in a fulminant manner and should be included in the differential diagnosis of acute multiple mononeuropathies. The possible causes for such a rapid clinical course in our patient are discussed.

Natural history of 46 patients with multifocal motor neuropathy with conduction block

We studied 46 consecutive patients with multifocal motor neuropathy with conduction block (MMN-CB). Typically, asymmetric weakness and atrophy of the hands or arms developed insidiously, but spontaneous improvement (without treatment) or death from this disease did not occur and 94% remained employed. For 18 patients examined on multiple occasions using the weakness subscore of the neuropathy impairment score [NIS(W)] for a median time of 2.3 years, worsening of 1.3 points per year was observed; many patients, however, had received intensive immunomodulating therapy. Median worsening to our first evaluation (generally without treatment) was estimated at 4.2 points per year, perhaps suggesting that treatment had influenced course. Three criteria for conduction block (CB) were compared, but the least stringent was sensitive for the diagnosis. Conduction block accompanied by weakness and atrophy typically affected only motor fibers, especially of midforearm nerves, and these sites of dysfunction persisted for months or years. Neurological signs and electrodiagnostic features were consistent with CB, axonal degeneration, a variable degree of reinnervation, and segmental demyelination. Although this study did not focus on therapy, intravenous gammaglobulin and cyclophosphamide appeared to be associated with neurological improvement, which was seldom complete or sustained. Axonal degeneration and faulty regeneration may in part explain this muted response. Possibly, treatment must be earlier, more intense, or different.

Microvasculitis in non-diabetic lumbosacral radiculoplexus neuropathy (LSRPN): similarity to the diabetic variety (DLSRPN)

Diabetic lumbosacral radiculoplexus neuropathy (DLSRPN) has been shown to be due to ischemic injury from microvasculitis. The present study tests whether ischemic injury and microvasculitis are the pathologic cause of non-diabetic lumbosacral radiculoplexus neuropathy (LSRPN), and whether the pathologic alterations are different between LSRPN and DLSRPN. We studied distal cutaneous nerve biopsies of 47 patients with LSRPN and compared findings with those of 14 age-matched healthy controls and 33 DLSRPN patients. In both disease conditions, we found evidence of ischemic injury (multifocal fiber degeneration and loss, perineurial degeneration and scarring, characteristic fiber alterations, neovascularization, and injury neuroma) that we attribute to microvasculitis (mural and perivascular mononuclear inflammation of microvessels, inflammatory separation, fragmentation and destruction of mural smooth muscle, and previous microscopic bleeding [hemosiderin]). Teased nerve fibers in LSRPN showed significantly increased frequencies of axonal degeneration, segmental demyelination, and empty nerve strands. The segmental demyelination appeared to be clustered on fibers with axonal dystrophy. The nerves with abnormal frequencies of demyelination were significantly associated with nerves showing multifocal fiber loss. We reached the following conclusions: 1) LSRPN is a serious condition with much morbidity that mirrors DLSRPN. 2) Ischemic injury from microvasculitis appears to be the cause of LSRPN. 3) Axonal degeneration and segmental demyelination appear to be linked and due to ischemia. 4) The pathologic alterations in LSRPN and DLSRPN are indistinguishable, raising the question whether these 2 conditions have a common underlying mechanism, and whether diabetes mellitus contributes to the pathology or is a risk factor in DLSRPN. 5) Both LSRPN and DLSRPN are potentially treatable conditions.

Hereditary motor and sensory neuropathy type 2C is genetically distinct from types 2B and 2D

BACKGROUND

Linkage analysis studies have identified 3 genetically different varieties of hereditary motor and sensory neuropathy type 2 (HMSN 2, also called Charcot-Marie-Tooth disease type 2, or CMT 2): HMSN 2A (linked to 1p35-p36), 2B (to 3q13-q22), and 2D (to 7p14). Hereditary motor and sensory neuropathy type 2C is characterized by diaphragmatic and vocal cord paresis; its disease locus has not been mapped.

OBJECTIVE

To determine whether the HMSN 2C phenotype, previously shown not to be linked to the HMSN 2A locus, is linked to the HMSN 2B or HMSN 2D loci.

DESIGN

Linkage analysis.

SETTING AND PATIENTS

Thirty-three subjects, including 12 affected individuals and 11 individuals at risk, in a large family with HMSN 2C.

RESULTS

Evidence was found against linkage of HMSN 2C phenotype to either the HMSN 2B or the 2D loci.

CONCLUSIONS

HMSN 2C is genetically distinct from HMSN 2A, 2B, and 2D. We think that at least 4 genetically distinct varieties of autosomal dominant HMSN 2 exist.

Patterns of quantitative sensation testing of hypoesthesia and hyperalgesia are predictive of diabetic polyneuropathy: a study of three cohorts. Nerve growth factor study group

OBJECTIVE

To test quantitative sensation testing (QST) patterns of hypoesthesia and hyperalgesia as indicators of diabetic polyneuropathy (DPN) and its severity

RESEARCH DESIGN AND METHODS

We used Computer-Assisted Sensory Examination IV; characterized the QST results of the foot of each patient in three diabetic cohorts (approximately 1,500 patients) as hyperesthetic (< or = 2.5th percentile), low-normal (2.5th-50th percentiles), high-normal (50th-97.5th percentiles), or hypoesthetic (> or = 97.5th percentile); and tested associations with symptoms, impairments, and test abnormalities.

RESULTS

Overall neuropathic impairment was most severe in the pancreas-renal transplant and nerve growth factor cohorts, but it was much less severe in the population-based Rochester Diabetic Neuropathy Study (RDNS) cohort. The frequency distribution of sensory abnormalities mirrored this difference. When the QST spectra of diabetic cohorts were compared with those of the control subject cohort for vibration and cooling sensations, the only abnormality observed was hypoesthesia, which was expressed as an increased number of subjects with values at or above the 97.5th percentile or by an increased percentage of cases with high-normal values. Symptoms and impairments of DPN were significantly more frequent in the subjects with values at or above the 97.5th percentile than in the subjects whose values were between the 50th and 97.5th percentiles. For heat pain (HP) sensation thresholds (intermediate pain severity [HP:5], pain threshold [HP:0.5], and pain-stimulus response slope [HP:5-0.5]), an increased frequency of both hypoalgesia and hyperalgesia was observed (especially in the RDNS cohort). Steeper pain-stimulus response slopes were significantly associated with sensory symptoms, including severity of pain.

CONCLUSIONS

1) Decreased vibratory sensation (hypoesthesia) appears to be characteristic of mild DPN, whereas panmodality hypoesthesia is characteristic of severe DPN. 2) A shift of vibratory and cold detection thresholds (and also of attributes of nerve conduction and a measure of autonomic dysfunction) from low-normal (2.5th-50th percentiles) to high-normal (50th-97.5th percentiles) appears to precede overt expression of DPN and to thereby provide evidence of subclinical abnormality 3) Heat stimulus-induced hyperesthesia (low thresholds) occurs especially in mild DPN, and, because it correlates with DPN symptoms and impairments, it must be attributed to hyperalgesia rather than to supersensitivity Therefore, hypoalgesia or hyperalgesia may be an indicator of early DPN.

Microvasculitis and ischemia in diabetic lumbosacral radiculoplexus neuropathy

OBJECTIVE

To determine whether microscopic vasculitis explains the clinical and pathologic features of diabetic lumbosacral radiculoplexus neuropathy (DLSRPN).

BACKGROUND

DLSRPN is usually attributed to metabolic derangement or ischemic injury, but microscopic vasculitis as the sole cause needs consideration.

METHODS

We prospectively studied the clinical, laboratory, and EMG features as well as the pathology of distal cutaneous nerve biopsy specimens of patients with DLSRPN.

RESULTS

Study of DLSRPN nerve biopsy specimens (n = 33) compared with those from healthy controls (n = 14) and those with diabetic polyneuropathy (n = 21) provided strong evidence for ischemic injury (axonal degeneration, multifocal fiber loss, focal perineurial necrosis and thickening, injury neuroma, neovascularization, and swollen fibers with accumulated organelles), which we attribute to microscopic vasculitis (epineurial vascular and perivascular inflammation, vessel wall necrosis, and evidence of previous bleeding). Segmental demyelination was significantly associated with multifocal fiber loss.

CONCLUSIONS

1) This severe, debilitating neuropathy begins with symptoms unilaterally and focally in the leg, thigh, or buttock and spreads to involve the other regions of the same and then opposite side and is due to multifocal involvement of lumbosacral roots, plexus, and peripheral nerve (i.e., diabetic lumbosacral radiculoplexus neuropathy). 2) Motor, sensory, and autonomic fibers are all involved. 3) Ischemic injury explains the clinical features and pathologic abnormalities of nerve. 4) The proximate cause of the ischemic injury appears to be microscopic vasculitis. 5) The segmental demyelination is probably secondary to ischemic axonal dystrophy, thus providing a unifying hypothesis for both axonal degeneration and segmental demyelination.

Effect of simple analgesics on quantitative sensation test threshold

Twenty individuals underwent quantitative sensation testing (QST) before and after 1 dose of aspirin, acetaminophen, or acetaminophen with codeine to determine the effect of analgesics on QST results. There was no significant change from baseline when mean QST results after placebo were compared to mean QST results after analgesics. We conclude that the effect of small doses of simple analgesics on QST results is either not present or is too small to necessitate withholding analgesics before sensory testing.

Risk factors for severity of diabetic polyneuropathy: intensive longitudinal assessment of the Rochester Diabetic Neuropathy Study cohort

OBJECTIVE

Chronic hyperglycemia relates to the occurrence of diabetic polyneuropathy (DPN), but has not yet been shown to relate to its overall severity In addition, the degree and duration of hyperglycemia, which measure of chronic hyperglycemia is most predictive of defined levels of severity of DPN, and which other putative risk factors are involved remain unknown.

RESEARCH DESIGN AND METHODS

In a longitudinal study of 264 diabetic individuals in Rochester, MN, risk factors and other diabetic complications assessed at regular intervals during an average of approximately 7 years were tested for their association with a composite score of severity of DPN at the last examination.

RESULTS

In multivariate analysis, diabetic retinopathy severity level (at last examination), mean ln(24-h proteinuria x duration of diabetes), and mean GHb were the main covariates for severity of DPN (R2 = 0.33). Excluding markers of microvessel and macrovessel disease, the independent risk factors were mean In(GHb x duration of diabetes), GHb, and type of diabetes (R2 = 0.23).

CONCLUSIONS

We found that diabetic microvessel disease, chronic hyperglycemia exposure, and type of diabetes are associated with severity of DPN, and we believe these factors are implicated in its cause. Each of the five markers of microvessel disease was a strong covariate for severity of DPN. Mean GHb predicts severity of DPN better than duration of diabetes, and the latter predicts severity of DPN better than mean fasting plasma glucose. Knowing the severity of microvessel disease, the degree of chronic hyperglycemia exposure, and the type of diabetes provides useful information to evaluate whether a coexisting polyneuropathy and its severity is probably due to diabetes.

Isolated paralysis of the extensor digitorum communis associated with the posterior (Thompson) approach to the proximal radius

Seven patients presented with an isolated extensor digitorum communis (EDC) palsy immediately after undergoing surgery in which the posterior (Thompson) approach to the proximal radius was used. All had normal neurologic examination findings documented prior to surgery. In an attempt to localize this lesion, the authors studied the arborization of the terminal motor branches of the posterior interosseous nerve (PIN) at the distal edge of the supinator. A common innervation pattern to the superficial extensor muscles was observed in 29 of 30 cadaveric limbs. In 10 of 10 specimens, when the EDC was subdivided into its individual bellies, a reproducible pattern emerged: the proximal EDC muscles of the middle and ring fingers were supplied primarily by the recurrent nerve branch(es) and the EDC muscles of the index and little fingers, by separate nerve branches. Consistent with our anatomic findings, perioperative stimulation of the recurrent branch in 1 neurologically intact patient resulted in middle and ring finger extension. Electromyography in 8 normal limbs showed that the middle and ring fingers could be activated together without the index and little fingers in all cases. We believe that these patients with isolated EDC nerve palsy may have sustained an iatrogenic injury to EDC motor branches, distal to the supinator rather than to a PIN fascicle near the proximal supinator.

Effect of age and gender on sudomotor and cardiovagal function and blood pressure response to tilt in normal subjects

Normative data are limited on autonomic function tests, especially beyond age 60 years. We therefore evaluated these tests in a total of 557 normal subjects evenly distributed by age and gender from 10 to 83 years. Heart rate (HR) response to deep breathing fell with increasing age. Valsalva ratio varied with both age and gender. QSART (quantitative sudomotor axon-reflex test) volume was consistently greater in men (approximately double) and progressively declined with age for all three lower extremity sites but not the forearm site. Orthostatic blood pressure reduction was greater with increasing age. HR at rest was significantly higher in women, and the increment with head-up tilt fell with increasing age. For no tests did we find a regression to zero, and some tests seem to level off with increasing age, indicating that diagnosis of autonomic failure was possible to over 80 years of age.

Effect of age and gender on sudomotor and cardiovagal function and blood pressure response to tilt in normal subjects

Normative data are limited on autonomic function tests, especially beyond age 60 years. We therefore evaluated these tests in a total of 557 normal subjects evenly distributed by age and gender from 10 to 83 years. Heart rate (HR) response to deep breathing fell with increasing age. Valsalva ratio varied with both age and gender. QSART (quantitative sudomotor axon-reflex test) volume was consistently greater in men (approximately double) and progressively declined with age for all three lower extremity sites but not the forearm site. Orthostatic blood pressure reduction was greater with increasing age. HR at rest was significantly higher in women, and the increment with head-up tilt fell with increasing age. For no tests did we find a regression to zero, and some tests seem to level off with increasing age, indicating that diagnosis of autonomic failure was possible to over 80 years of age.

A case-control and nerve biopsy study of CREST multiple mononeuropathy

From 536 patients with the CREST syndrome (calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasis), seven were identified as having peripheral neuropathy not attributable to another cause. Peripheral neuropathy developed 0 to 25 years after their first symptoms of scleroderma. Unexplained neuropathy in CREST patients (seven patients) was more frequent than in control subjects (two patients) matched for age, sex, time of evaluation, and geographic referral region. Multiple mononeuropathy occurred significantly more frequently in the CREST group (six patients) than in the control group (0 patients). Four sural nerve biopsy specimens from the CREST patients demonstrated multifocal fiber loss and perivascular inflammation; one was diagnostic for necrotizing vasculitis and two others were highly suggestive for necrotizing vasculitis. The density of myelinated fibers in three nerves from CREST patients was significantly decreased, whereas the index of dispersion (a measure of multifocal fiber loss) was increased, and the frequency of axonal degeneration was significantly increased. Based on these clinical and pathologic findings, we conclude that in the CREST syndrome multiple mononeuropathy, although occurring infrequently, occurs more frequently than by chance and necrotizing vasculitis is the cause of this multiple mononeuropathy.