Distal symmetric polyneuropathy (DSP) is the most common variety of neuropathy. Since the evaluation of this disorder is not standardized, the available literature was reviewed to provide evidence-based guidelines regarding the role of autonomic testing, nerve biopsy and skin biopsy for the assessment of polyneuropathy.
A literature review using MEDLINE, EMBASE, Science Citation Index and Current Contents was performed to identify the best evidence regarding the evaluation of polyneuropathy published between 1980 and March 2007. Articles were classified according to a four-tiered level of evidence scheme and recommendations were based upon the level of evidence.
1. Autonomic testing may be considered in the evaluation of patients with polyneuropathy to document autonomic nervous system dysfunction (Level B). Such testing should be considered especially for the evaluation of suspected autonomic neuropathy (Level B) and distal small fiber sensory polyneuropathy (SFSN) (Level C). A battery of validated tests is recommended to achieve the highest diagnostic accuracy (Level B). 2. Nerve biopsy is generally accepted as useful in the evaluation of certain neuropathies as in patients with suspected amyloid neuropathy, mononeuropathy multiplex due to vasculitis, or with atypical forms of chronic inflammatory demyelinating polyneuropathy (CIDP). However, the literature is insufficient to provide a recommendation regarding when a nerve biopsy may be useful in the evaluation of DSP (Level U). 3. Skin biopsy is a validated technique for determining intraepidermal nerve fiber (IENF) density and may be considered for the diagnosis of DSP, particularly SFSN (Level C). There is a need for additional prospective studies to define more exact guidelines for the evaluation of polyneuropathy.
"The rising incidence of diabetes and its negative impact on quality of life highlights the urgent need to develop biomarkers of early nerve damage. The gold-standard method to evaluate morphological change in small nerve fibres was the skin biopsy ; however, this technique is limited by cost and invasiveness, provides no information about the function of nerve fibres, and cannot be employed as a generalized screening test in all patients. "
[Show abstract][Hide abstract] ABSTRACT: The rising incidence of diabetes and its negative impact on quality of life highlights the urgent need to develop biomarkers of early nerve damage. Measurement of total vitamin B12 has some limitations. We want to determine the levels of urinary methylmalonic acid and its relationships with serum vitamin B12 and polyneuropathy. The 176 Chinese patients with Type 2 diabetes mellitus were divided into 3 groups according to the levels of vitamin B12. A gas chromatography mass spectrometric technique was used to determine blood methylmalonic acid and urinary methylmalonic acid. The diagnosis of distal diabetic polyneuropathy was based on the determination of bilateral limb sensory and motor nerve conduction velocity and amplitude with electromyogram. Multiple regression analysis revealed that urinary methylmalonic acid/creatinine, blood methylmalonic acid, and so forth were variables that influenced diabetic polyneuropathy significantly. Nerve sensory conduction velocity and nerve amplitude in the group of urinary methylmalonic acid/creatinine >3.5 mmol/mol decreased significantly. Superficial peroneal nerve sensory and motor conduction velocity and ulnar nerve compound motor active potential amplitude were inversely correlated with urinary methylmalonic acid/creatinine. Urinary methylmalonic acid correlates with serum vitamin B12 levels in person with diabetes and is a sensitive marker of early polyneuropathy.
Journal of Diabetes Research 02/2014; 2014:921616. DOI:10.1155/2014/921616 · 2.16 Impact Factor
"IENF degeneration has been described in several chronic conditions, such as diabetic neuropathy [27,28], but also in acute inflammatory neuropathies, such as Guillain-Barré syndrome [11-14]. Patients with SFN typically present with neuropathic pain and reduced thermal and pain sensation but with normal strength, proprioceptive sensation, and deep tendon reflexes reflecting normal large nerve fiber functions [9,10,29,30]. At skin biopsy, reduced IENF density is typically demonstrated . "
[Show abstract][Hide abstract] ABSTRACT: Degeneration of intraepidermal nerve fibers (IENF) is a hallmark of small fiber neuropathy of different etiology, whose clinical picture is dominated by neuropathic pain. It is unknown if critical illness can affect IENF.
We enrolled 14 adult neurocritical care patients with prolonged intensive care unit (ICU) stay and artificial ventilation (≥ 3 days), and no previous history or risk factors for neuromuscular disease. All patients underwent neurological examination including evaluation of consciousness, sensory functions, muscle strength, nerve conduction study and needle electromyography, autonomic dysfunction using the finger wrinkling test, and skin biopsy for quantification of IENF and sweat gland innervation density during ICU stay and at follow-up visit. Development of infection, sepsis and multiple organ failure was recorded throughout the ICU stay.
Of the 14 patients recruited, 13 (93%) had infections, sepsis or multiple organ failure. All had severe and non-length dependent loss of IENF. Sweat gland innervation was reduced in all except one patient. Of the 7 patients available for follow-up visit, three complained of diffuse sensory loss and burning pain, and another three showed clinical dysautonomia.
Small fiber pathology can develop in the acute phase of critical illness and may explain chronic sensory impairment and pain in neurocritical care survivors. Its impact on long term disability warrants further studies involving also non-neurologic critical care patients.
PLoS ONE 09/2013; 8(9):e75696. DOI:10.1371/journal.pone.0075696 · 3.23 Impact Factor
"In the natural history of DSP, it is hypothesized that early subclinical small-fiber damage precedes large-fiber impairment and the presentation of common clinical signs and symptoms. The gold standard for assessing small nerve fiber degeneration is the morphometry of intraepidermal nerve fiber density measured by skin punch biopsy, which is an invasive and painful technique (32). This quantitative relationship between severity of DSP and intraepidermal nerve fiber density is equivalently paralleled by corneal nerve fiber morphology, measured by IVCCM (23). "
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVE
In vivo corneal confocal microscopy (IVCCM) has been proposed as a noninvasive technique to assess small nerve fiber structural morphology. We investigated the structure-function relationship of small fibers in diabetic sensorimotor polyneuropathy (DSP).RESEARCH DESIGN AND METHODS
Ninety-six type 1 diabetic subjects with a spectrum of clinical DSP and 64 healthy volunteers underwent IVCCM examinations to determine corneal nerve structure, including corneal nerve fiber length (CNFL), fiber density (CNFD), branch density (CNBD), and fiber tortuosity (CNFT). Small nerve fiber function was assessed by cooling detection thresholds (CDTs), axon reflex-mediated neurogenic vasodilatation in response to cutaneous heating by laser Doppler imaging flare technique (LDIFLARE), and heart rate variability (HRV). Linear associations between structural and functional measures in type 1 diabetic subjects were determined using Spearman correlation coefficients and linear regression analysis.RESULTSOf the type 1 diabetic subjects, with a mean age of 38.2 ± 15.5 years and a mean HbA1c of 7.9 ± 1.4%, 33 (34%) had DSP according to the consensus definition. Modest correlations were observed between CNFL, CNFD, and CNBD and all functional small-fiber tests (rs = 0.25 to 0.41; P ≤ 0.01 for all comparisons). For example, quantitatively every 1 mm/mm(2) lower CNFL was associated with a 0.61°C lower CDT, a 0.07 cm(2) lower LDIFLARE area, and a 1.78% lower HRV. No significant associations were observed for CNFT and the functional small-fiber measures.CONCLUSIONS Small nerve fiber structural morphology assessed by IVCCM correlated well with functional measures of small nerve fiber injury. In particular, CNFL, CNFD, and CNBD demonstrated clear structure-function relationships.
Diabetes care 04/2013; 36(9). DOI:10.2337/dc12-2075 · 8.42 Impact Factor
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