Amyloid and peripheral nervous system disease

Amyloid Proteins and Peripheral Neuropathy

Painful peripheral neuropathy affects millions of people worldwide. Peripheral neuropathy develops in patients with various diseases, including rare familial or acquired amyloid polyneuropathies, as well as some common diseases, including type 2 diabetes mellitus and several chronic inflammatory diseases. Intriguingly, these diseases share a histopathological feature-deposits of amyloid-forming proteins in tissues. Amyloid-forming proteins may cause tissue dysregulation and damage, including damage to nerves, and may be a common cause of neuropathy in these, and potentially other, diseases. Here, we will discuss how amyloid proteins contribute to peripheral neuropathy by reviewing the current understanding of pathogenic mechanisms in known inherited and acquired (usually rare) amyloid neuropathies. In addition, we will discuss the potential role of amyloid proteins in peripheral neuropathy in some common diseases, which are not (yet) considered as amyloid neuropathies. We conclude that there are many similarities in the molecular and cell biological defects caused by aggregation of the various amyloid proteins in these different diseases and propose a common pathogenic pathway for "peripheral amyloid neuropathies".

MRI analysis of carpal tunnel syndrome in hemodialysis patients versus non-hemodialysis patients: a multicenter case-control study

BACKGROUND

Carpal tunnel syndrome (CTS) is common among patients receiving hemodialysis and deeply influences their daily life. Amyloid deposits are considered the main reason for median nerve compression, but its prevalence is unclear. Therefore, to determine the main region of amyloid deposition inside the carpal tunnel, we measured the cross-sectional area (CSA) of each component of the carpal tunnel in preoperative magnetic resonance imaging (MRI).

METHODS

Thirty-five hemodialysis patients (HD group) and age- and sex-matched 35 non-hemodialysis patients (non-HD group), who underwent the first surgery for CTS in registered hospitals from 2005 to 2015, were retrospectively enrolled. CTS was diagnosed from clinical and electromyographic (EMG) findings. The CSA of carpal tunnel, each of the flexor tendons, and the median nerve at the level of the hook of hamate were measured in T1-weighted axial images in preoperative MRI, by using Synapse OP-A software. Statistical analysis was performed using the Student's t test and Pearson's chi-squared test.

RESULTS

The mean age of the HD group was 65.9 years and the dialysis duration was 21.9 (11-35) years. The mean age of the non-HD group was 65.3 years. The CSA of carpal tunnel (p = 0.006), flexor tendon (p = 0.03), and flexor digitorum profundus (FDP) tendon (p = 0.04) were bigger in the HD group. However, the median nerve, the flexor digitorum superficialis (FDS) tendon, and the flexor pollicis longus tendon (FPL) were not significantly different between the two groups. The dialysis duration or age at surgery did not show any strong correlation to each CSA.

CONCLUSIONS

We confirmed that hemodialysis caused expansion of the carpal tunnel due to amyloid deposition as previously described. Hemodialysis also caused expansion of the CSA of the flexor tendon, especially the FDP, possibly because of amyloid deposition inside the tendon. Furthermore, the duration of dialysis or age did not correlate with any CSA, which could be due to the good progress of the beta 2-microglobulin removal technique. Based on our results, FDS excision could be considered in case severe deposition of amyloid in FDP is observed during surgery.

The impact of cellular networks on disease comorbidity

The impact of disease-causing defects is often not limited to the products of a mutated gene but, thanks to interactions between the molecular components, may also affect other cellular functions, resulting in potential comorbidity effects. By combining information on cellular interactions, disease--gene associations, and population-level disease patterns extracted from Medicare data, we find statistically significant correlations between the underlying structure of cellular networks and disease comorbidity patterns in the human population. Our results indicate that such a combination of population-level data and cellular network information could help build novel hypotheses about disease mechanisms.

'Non-neuronopathic' Gaucher disease reconsidered. Prevalence of neurological manifestations in a Dutch cohort of type I Gaucher disease patients and a systematic review of the literature

Gaucher disease is a lysosomal storage disorder, which is classically divided into three types. Type I Gaucher disease is differentiated from types II and III disease by the absence of nervous system involvement. However, an increasing number of reports has emerged on neurological manifestations in patients with type I Gaucher disease. Whether a strict division in three different phenotypes is still valid has been the subject of debate. The main objective of this study was to provide scientific arguments whether a distinction between type I (non-neuronopathic) and types II and III (neuronopathic) Gaucher disease should be maintained. We investigated retrospectively a large Dutch cohort of type I Gaucher disease patients for the prevalence of neurological manifestations and provide an overview of the literature on this topic. A diagnosis of a neurological disease was made 34 times in 75 patients. Forty-five patients reported at least one neurological symptom during the median follow-up time of 11 years. The literature search revealed 86 studies in which type I Gaucher disease patients or carriers of a glucocerebrosidase mutation were described with a neurological disease or a condition which is known to be associated with neurological disease. In conclusion, the term non-neuronopathic Gaucher disease does not seem to be an appropriate characterization of type I Gaucher disease. However, the neurological signs and symptoms in type I Gaucher disease are of a totally different kind from and, in the majority of cases, of much less severity than the signs and symptoms associated with types II and III disease Therefore, type I disease should be classified as a separate phenotype.

Amyloidosis: diagnosis and management

Amyloidosis is a rare plasma cell proliferative disorder. The annual incidence in Olmsted County, Minnesota, is 8 in 1,000,000 patients. This is a difficult disorder to diagnose, because the symptoms at presentation are vague and include dyspnea, paresthesias, edema, weight loss, and fatigue. The clinical syndromes at the time of presentation include nephrotic-range proteinuria with or without renal failure, cardiomyopathy, "atypical multiple myeloma," hepatomegaly, and autonomic or peripheral neuropathy. The serum immunoglobulin free light chain assay has been an important step forward in classifying systemic amyloidosis as an immunoglobulin light chain form and in monitoring therapy. Recently, the importance of serum cardiac biomarkers in assessing outcome has been recognized. New therapies developed over the past 5 years include high-dose chemotherapy with stem cell reconstitution, combinations of alkylating agents with dexamethasone, and, most recently, thalidomide.

Amyloidosis

Amyloidosis is an uncommon plasma-cell dyscrasia with an incidence of eight patients per million per year. It is often difficult to recognize because of the myriad symptoms and vague nature of the clinical presentation. Symptoms include fatigue, dyspnea, edema, paresthesias, and weight loss. Clinical syndromes at presentation include nephrotic-range proteinuria with or without renal insufficiency, cardiomyopathy, hepatomegaly, symptomatic peripheral neuropathy, and autonomic failure. Recent advances have occurred in evaluation of patients by using the free light chain assay and new prognostic assessments with cardiac biomarkers. Newly developed therapeutic strategies, involving high-dose and intermediate-dose chemotherapy, have evolved in the last 3 years. This paper reviews a diagnostic pathway clinicians can use to diagnose the disorder, assess a patient's prognosis, and logically plan a therapeutic strategy.

Familial carpal tunnel syndrome: a report of a Finnish family

The existence of familial carpal tunnel syndrome (FCTS) as a separate autonomic entity has been discussed during the last few years. In order to contribute with more data to the literature, we report here the results of clinical. electrophysiological, pathological and radiological studies performed in 5 patients belonging to the same Finnish pedigree. The disease appeared usually before the second decade with numbness and pain on the I--III digits. In most patients symptoms were unilateral but within 2 years they became bilateral. In all patients typical electrophysiological features of median nerve entrapment have been recorded. X-rays of the wrist showed narrow carpal tunnel in all patients. In all patients the possibility of having HNPP as well as familial amyloidosis has been excluded by molecular genetic and pathological studies. All patients underwent surgery and at postoperative stage symptoms were relieved or completely disappeared. Our study supports the theory that FCTS exists as a separate autonomic entity, therefore it is important in front of a sporadic case to investigate the family occurrence of CTS.

Peripheral nerve amyloidosis in sural nerve biopsies: a clinicopathologic analysis of 13 cases

OBJECTIVE

Amyloidosis is a well-recognized but uncommon cause of peripheral neuropathy. Our objectives were to determine the overall prevalence of peripheral nerve amyloidosis in sural nerve biopsies and to evaluate the clinical and pathologic features of these lesions.

METHODS

All available histologic and ultrastructural materials on biopsy tissue from 13 cases of peripheral nerve amyloidosis were examined. Muscle biopsies performed at the same time as the nerve biopsy were reviewed when available. Clinical data were collected on all patients.

RESULTS

The prevalence of amyloidosis in sural nerve biopsies at our institution was 13 (1.2%) of 1098 cases over a 15.8-year period. These patients ranged in age from 41 to 82 years (median, 61 years) at initial presentation and included 10 men and 3 women. Presenting neuropathy symptoms were sensory in 6 of the 13 patients, motor in 2 cases, and mixed in 5 cases. Cardiac, renal, or gastrointestinal involvement was present in 7 of 13 cases. Two patients had myeloma and 7 had systemic autonomic symptoms. Two patients had probable familial amyloid polyneuropathy, and 1 patient demonstrated an alanine 60 point mutation. Amyloid, identified as amorphous eosinophilic extracellular deposits demonstrating apple green birefringence on Congo red stain or recognized by its characteristic fibrillar ultrastructure by electron microscopy, was identified in the endoneurium in 12 nerves, perineurium in 2 nerves, and epineurium in 9 nerves. Chronic inflammation was identified in 5 nerves. Axonal loss was recorded as mild (<25%) in 1 nerve, moderate (25% to 75%) in 8 nerves, and severe (>75%) in 4 nerves. Axonal degeneration predominated over demyelination in 8 of 10 cases that could be evaluated. Concomitant muscle biopsies contained amyloid deposits in 8 of 9 cases.

CONCLUSIONS

Amyloidosis is a rare (1.2% in our series) cause of peripheral neuropathy with a distinct microscopic and ultrastructural appearance. Just over half the patients in our study had visceral organ involvement and systemic autonomic symptoms. The peripheral neuropathy was associated with axonal degeneration and a moderate to severe axonal loss in the majority of cases. Amyloid deposition was present in 8 out of 9 muscle biopsies performed at the same time.

Is there a familial carpal tunnel syndrome? An evaluation and literature review

We review the reports of families proposed to have the familial carpal tunnel syndrome (FCTS). The demographic features of sporadic carpal tunnel syndrome (CTS) differ from FCTS, where an earlier onset and increased bilateral involvement is seen. We also identify seven new potential FCTS pedigrees on the basis of their having four or more members with symptoms suggesting CTS. In all but two pedigrees an explanation other than FCTS was found. We conclude that the FCTS is a rare, but genetically distinct disorder.

The hand and the eye

A variety of systemic diseases may affect both the hand and eye, leading to profound sensory and functional deficits. The aetiology of some of the most common conditions is reviewed, with an explanation of their manifestations in the hand and eye. Recognition of the association between a hand condition and ocular pathology may aid in diagnosis of a systemic disorder or allow early detection and prevention of ocular disease and loss of vision.