Electrophysiological Studies of Nerve Function in Patients on CAPD over Long Periods

The authors studied electrophyhsiological parameters in 29 patients (23 non-diabetics, six diabetics, mean age 47.9, range 16–74 yr.), who had been on CAPD for three to five years. The parameters studied were: motor nerve conduction velocities of the median, ulnar, and peroneal nerves, and sensory nerve conduction velocities of the median and ulnar nerves. These parameters were measured before or within the first month of CAPD and every six months thereafter. The changes in nerve conduction velocities were studied using simple linear regression analysis, and calculating the differences of the slopes from zero. Comparison of the mean values of the conduction velocities in non-diabetics at the beginning of CAPD and in age - matched, non uremic patients showed significantly (p < 0.001) lower values in all parameters measured. The initial nerve conduction velocities in diabetic patients were significantly (p < 0.01) slower than in non-diabetics except sensory conduction velocity of the ulnar nerve. The slopes of nerve conduction velocities plotted against time were not significantly different from zero for any nerve in both non-diabetics and diabetic patients. In conclusion, no significant change in peripheral nerve function was seen after long term CAPD in either diabetic or non-diabetic patients.

Chronic kidney disease and peripheral nerve function in the Health, Aging and Body Composition Study

BACKGROUND

Chronic kidney disease (CKD) is associated with poor mobility. Peripheral nerve function alterations play a significant role in low mobility. We tested the hypothesis that early CKD is associated with altered sensory, motor and autonomic nerve function.

METHODS

Participants in the Health, Aging and Body Composition cohort who had kidney function measures in Year 3 (1999-2000) and nerve function measurements at Year 4 (2000-01) were analyzed (n = 2290). Sensory (vibration threshold, monofilament insensitivity to light and standard touch), motor [compound motor action potentials (CMAPs), nerve conduction velocities (NCVs)] and autonomic (heart rate response and recovery after a 400-m walk test) nerve function as well as participant characteristics were compared across cystatin C- and creatinine-based estimated glomerular filtration rate categorized as ≤60 (CKD) or >60 mL/min/1.73 m2 (non-CKD). The association between CKD and nerve function was examined with logistic regression adjusted for covariates.

RESULTS

Participants with CKD (n = 476) were older (77 ± 3 versus 75 ± 3 years; P < 0.05) and had a higher prevalence of diabetes (20.6% versus 13.1%; P < 0.001). CKD was associated with higher odds for vibration detection threshold {odds ratio [OR] 1.7 [95% confidence interval (CI) 1.1-2.7]} and light touch insensitivity [OR 1.4 (95% CI 1.1-1.7)]. CMAPs and NCVs were not significantly different between CKD and non-CKD patients. In adjusted analyses, participants with CKD had higher odds of an abnormal heart rate response [OR 1.6 (95% CI 1.1-2.2)] and poor heart rate recovery [OR 1.5 (95% CI 1.1-2.0)].

CONCLUSIONS

CKD is associated with changes in sensory and autonomic nerve function, even after adjustment for demographics and comorbidities, including diabetes. Longitudinal studies in CKD are needed to determine the contribution of nerve impairments to clinically important outcomes.

Association between estimated glomerular filtration rate and outcomes in patients with diabetic foot ulcers: a 3-year follow-up study

OBJECTIVE

End-stage renal disease and dialysis have been proven to be associated with poor prognoses in diabetic foot ulcers (DFUs). However, it has rarely been reported whether and to what extent milder renal insufficiency affects the prognosis. The purpose of this study was to investigate the categorized impact of estimated glomerular filtration (eGFR) on the outcomes of patients with DFU.

DESIGN AND METHODS

Three hundred and sixty-six DFU patients hospitalized in a Chinese tertiary hospital were recruited and classified into 4 groups according to the eGFRs as follows: normal (≥90), mildly reduced (60-89), moderately reduced (30-59), and severely reduced (<30). These patients were followed-up for an average of 37 months to observe the outcomes, including ulcer healing, amputation, ulcer recurrence, cardiac or cerebrovascular events and death. The associations between eGFR and the outcomes were analysed by Cox proportional-hazards models.

RESULTS

Compared to patients with normal eGFR, patients with moderately reduced eGFR had higher risk of healing failure (hazard ratio (HR) = 2.08, 95% confidence interval (CI): 1.13-3.82), cardiac events (HR = 5.25, 95% CI: 2.17-12.89) and death (HR = 3.54, 95% CI: 1.36-9.20). Severely reduced eGFR was associated with higher incidence of healing failure (HR = 2.84, 95% CI: 1.25-6.49) and death (HR = 4.45, 95% CI: 1.23-16.07). The impact of eGFR on ulcer recurrence and cerebrovascular events was not observed in all groups.

CONCLUSIONS

Moderately and severely reduced eGFR in patients with DFU were independent predictors for poor prognoses of both the limbs and the patients.

Renal failure: implications of chronic kidney disease in the management of the diabetic foot

Foot complications are common in patients with diabetes, however, chronic kidney disease has emerged as an independent risk factor for development of foot lesions in the diabetic population. Apart from peripheral arterial disease, infection, and neuropathy, which are classic factors contributing to development of foot lesions, skin disorders specific to renal failure, impaired wound healing from uremia, and psychosocial issues offer further compounded risk. Consequently, there are high ulceration and amputation rates that are associated with increased morbidity and mortality. In recent studies, foot-care programs with a multidisciplinary approach within dialysis units have demonstrated improved outcomes.

Genomic damage in the progression of chronic kidney disease in rats

Patients with chronic renal failure exhibit massive oxidative genome damage and an elevated risk of cancer. Previous studies have demonstrated the relationship between DNA damage and carcinogenesis. The current study aimed to investigate whether the progression of chronic kidney disease induces genomic damage in an animal model. Adult Wistar rats were assigned to either the control or chronic kidney disease groups. The chronic kidney disease group was subdistributed into five groups with progressively longer durations of disease (30, 60, 90, 120 and 150 days). The results showed that chronic kidney disease induced genomic damage in the blood, liver and kidney cells during all periods evaluated, as indicated by the mean tail moment measured in the comet assay. In brain cells, no genetic damage was induced at early/intermediate disease durations; however, positive genotoxicity was found at 120 and 150 days. Blood pressure and pro-inflammatory cytokine levels (IL-1α, IL-1β, IL-6 and TNFα) were increased after chronic kidney disease induction, while blood iron concentration was significantly reduced in these animals. The results suggest that chronic kidney disease progression contributes to DNA damage in blood, liver, kidney and brain and that such damage can be mediated by hypertension, an inflammatory status and iron deficiency. Additionally, the brain was sensitive to genotoxic insult after extended chronic kidney disease, suggesting a potentially important role of genetic damage in the neurological disorders of end-stage renal patients.

Neurological complications of chronic kidney disease

Chronic kidney disease (CKD) is a critical and rapidly growing global health problem. Neurological complications occur in almost all patients with severe CKD, potentially affecting all levels of the nervous system, from the CNS through to the PNS. Cognitive impairment, manifesting typically as a vascular dementia, develops in a considerable proportion of patients on dialysis, and improves with renal transplantation. Patients on dialysis are generally weaker, less active and have reduced exercise capacity compared with healthy individuals. Peripheral neuropathy manifests in almost all such patients, leading to weakness and disability. Better dialysis strategies and dietary modification could improve outcomes of transplantation if implemented before surgery. For patients with autonomic neuropathy, specific treatments, including sildenafil for impotence and midodrine for intradialytic hypotension, are effective and well tolerated. Exercise training programs and carnitine supplementation might be beneficial for neuromuscular complications, and restless legs syndrome in CKD responds to dopaminergic agonists and levodopa treatment. The present Review dissects the pathophysiology of neurological complications related to CKD and highlights the spectrum of therapies currently available.

Neuromuscular disease in the dialysis patient: an update for the nephrologist

Neuromuscular disease is an extremely common complication of end-stage kidney disease (ESKD), manifesting in almost all dialysis patients, and leading to weakness, reduced exercise capacity, and disability. Recent studies have suggested that hyperkalemia may underlie the development of neuropathy. As such, maintenance of serum K(+) within normal limits between periods of dialysis in ESKD patients manifesting early neuropathic symptoms may reduce neuropathy development and progression. For patients with more severe neuropathic syndromes, increased dialysis frequency or a switch to high-flux dialysis may prevent further deterioration, while ultimately, renal transplantation is required to improve and restore nerve function. Exercise training programs are beneficial for ESKD patients with muscle weakness due to neuropathy or myopathy, and are capable of improving exercise tolerance and quality of life. Specific treatments have recently been evaluated for symptoms of autonomic neuropathy, including sildenafil for impotence and midodrine for intra-dialytic hypotension, and have been shown to be effective and well tolerated. Other important management strategies for neuropathy include attention to foot care to prevent callus and ulceration, vitamin supplementation, and erythropoietin. Treatment with membrane-stabilizing agents, such as amitryptiline and gabapentin, are highly effective in patients with painful neuropathy.

Neuromuscular Complications in Uremics: A Review

BACKGROUND

Uremia may be associated with various neurologic manifestations, particularly a polyneuropathy, but also with focal neuropathies such as carpal tunnel syndrome and shunt-related neuropathies. Myopathies can also be caused by uremia and its metabolic disarrangements.

REVIEW SUMMARY

This article reviews the clinical presentation, pathogenesis, and treatment of uremic polyneuropathy, focal neuropathies, and uremic myopathies.

CONCLUSION

Recognizing the presentation and pathogenesis of uremic polyneuropathies, mononeuropathies, and myopathies are important for their prevention and for proper management.

Uremic neuropathy: clinical features and new pathophysiological insights

Neuropathy is a common complication of end-stage kidney disease (ESKD), typically presenting as a distal symmetrical process with greater lower-limb than upper-limb involvement. The condition is of insidious onset, progressing over months. and has been estimated to be present in 60%-100% of patients on dialysis. Neuropathy generally only develops at glomerular filtration rates of less than 12 ml/min. The most frequent clinical features reflect large-fiber involvement, with paresthesias, reduction in deep tendon reflexes, impaired vibration sense, muscle wasting, and weakness. Nerve conduction studies demonstrate findings consistent with a generalized neuropathy of the axonal type. Patients may also develop autonomic features, with postural hypotension, impaired sweating, diarrhea, constipation, or impotence. The development of uremic neuropathy has been related previously to the retention of neurotoxic molecules in the middle molecular range, although this hypothesis lacked formal proof. Studies utilizing novel axonal excitability techniques have recently shed further light on the pathophysiology of this condition. Nerves of uremic patients have been shown to exist in a chronically depolarized state prior to dialysis, with subsequent improvement and normalization of resting membrane potential after dialysis. The degree of depolarization correlates with serum K(+), suggesting that chronic hyperkalemic depolarization plays an important role in the development of nerve dysfunction in ESKD. These recent findings suggest that maintenance of serum K(+) within normal limits between periods of dialysis, rather than simple avoidance of hyperkalemia, is likely to reduce the incidence and severity of uremic neuropathy.

Cardiovascular Risk Factors Predicting the Development of Distal Symmetrical Polyneuropathy in People with Type 1 Diabetes: A 9-Year Follow-up Study

The aim of the article was to use prospectively collected data on people with type 1 diabetes to examine which routinely collected clinical measures predict the development of peripheral neuropathy in people with type 1 diabetes. Within the Newcastle Diabetes Services, structured data collection at an annual review has been collected since 1985. This includes metabolic measures, cardiovascular risk factors, and markers of complications. From 1990 data collection was standardized and computerized. For this study, all people with type 1 diabetes in the database in both 1992 and 2001 were ascertained. Data were extracted for a diagnosis of peripheral neuropathy (based on neuropathic symptoms, absence of pinprick sensation, and abnormal biothesiometer measurements and/or monofilament sensation) and for the other metabolic and cardiovascular risk measures, as well as markers of other microvascular complications. Associations with the development of neuropathy were sought. Eighteen of 404 people already had peripheral neuropathy in 1992, and 38 others developed neuropathy during follow-up. People who developed neuropathy were older (47 +/- 14 [SD] versus 36 +/- 11 years; P = 0.000), had longer-duration of diabetes (27 +/- 13 versus 18 +/- 10 years; P = 0.001), higher baseline serum cholesterol (5.8 +/- 1.3 versus 5.2 +/- 1.2 mmol/L, P = 0.017), and higher systolic (139 +/- 18 versus 129 +/- 20 mmHg; P = 0.003) and diastolic BP (82 +/- 12 versus 76 +/- 11 mmHg; P = 0.009) than those who remained free of neuropathy. We found no significant difference for BMI and glycated hemoglobin. The multivariate model showed that diastolic BP, duration of diabetes, serum cholesterol, and history of callus/ulcers on the feet predicted the development of peripheral neuropathy. Neuropathy developed in 11.4% of people with type 1 diabetes over a 9-year follow-up, and was predicted by factors normally associated with cardiovascular rather than microvascular disease.

Neurologic manifestations of renal disease

Mortality and morbidity from kidney disease and the spectrum of renal-associated neurologic disease have changed markedly since the introduction of renal dialysis and with the advent of renal transplantation. This article includes historical studies of the neurologic complications of acute uremia, now fairly uncommon, and recent literature regarding neurologic side effects associated with dialysis and renal transplantation.

Acute effect of hemodialysis on sympathetic skin response

Sympathetic skin response (SSR) is a useful and simple test for unmyelinated axon function in peripheral sensorimotor neuropathies. SSR was tested on a group of patients undergoing chronic regular hemodialysis before and after a single dialysis session. Nineteen patients in hemodialysis for more than three months were included. Nine patients were on dialysis with cellulosic membranes (CA, 3 male and 6 female, aged 57.7 +/- 16.4 years) and ten ones were on dialysis with non-cellulosic membranes (NC, 4 male and 6 female, aged 50.2 +/- 15.9 years) were studied. There were no differences neither in Kt/V values (NC 1.37 +/- 0.34 vs. CA 1.22 +/- 0.27) nor in TAC ones (NC 41.5 +/- 18.2 vs. CA 41.3 +/- 14.1 mg/dL). After hemodialysis with NC amplitude significantly increased (994 +/- 1015 vs. 382 +/- 465 microv baseline, p < 0.05). Latency did not change (1.76 +/- 0.83 vs. 2.07 +/- 0.50 s baseline). After hemodialysis with CA neither amplitude changed (1368 +/- 1074 vs. 1240 +/- 1594 microv baseline), nor did latency (1.79 +/- 0.35 vs. 1.94 +/- 0.59 s baseline). Hemodialysis with non-cellulosic membranes (but not with cellulose acetate) yields a short-term improvement of sympathetic skin response. This effect is similar to those seen in nerve conduction velocities and it may be related to increased middle-molecules depuration.

Nontraumatic lower extremity amputations in the Medicare end-stage renal disease population

BACKGROUND

Nontraumatic lower limb amputation is a serious complication of both diabetic neuropathy and peripheral vascular disease. Many people with end-stage renal disease (ESRD) suffer from advanced progression of these diseases. This study presents descriptive information on the rate of lower limb amputation among people with ESRD who are covered by the Medicare program.

METHODS

Using hospital bill data for the years 1991 through 1994 from the Health Care Financing Administration's ESRD program management and medical information system (PMMIS), amputations were based on ICD9 coding. These hospitalizations were then linked back to the PMMIS enrollment database for calculation of rates.

RESULTS

The rate of lower limb amputation increased during the four-year period from 4.8 per 100 person years in 1991 to 6.2 in 1994. Among persons whose renal failure was attributed to diabetic nephropathy, the rates in 1991 and 1994 were 11.8 and 13.8, respectively. The rate among diabetic persons with ESRD was 10 times as great as among the diabetic population at large. Two thirds died within two years following the first amputation.

CONCLUSIONS

The ESRD population is at an extremely high risk of lower limb amputation. Coordinated programs to screen for high-risk feet and to provide regular foot care for those at high risk combined with guidelines for treatment and referral of ulceration are needed.

Acquired peripheral neuropathy

This article reviews the acquired causes of polyneuropathy other than diabetic and acute-onset neuropathies. The author gives a general method to simplify the diagnosis of chronic polyneuropathy. The acquired polyneuropathies are discussed under four main headings: metabolic disorders, toxic or deficiency states, infections, and immune-mediated. Recent advances in therapy are emphasized, and some illustrative case histories are provided.

Are nerve conduction studies useful for monitoring the adequacy of renal dialysis?

When hemodialysis was first used clinically, a peripheral neuropathy frequently emerged. The discovery that sufficient dialysis time would prevent the emergence of symptomatic neuropathy led to the routine use of nerve conduction studies (NCS) to monitor the "adequacy" of dialysis. Modern dialysis practice has evolved since then, and the patient population is markedly different. This report addresses the question of whether there is evidence to indicate that routine use of NCS is helpful to monitor the adequacy of present-day dialysis. A critical review of the available literature reveals that there is insufficient evidence to allow one to answer the question.

A multimodal neurophysiological assessment in terminal renal failure

A prospective multimodal neurophysiological study was conducted on 36 patients with end-stage renal failure, 16 of whom subsequently underwent renal transplantation (TR). Nerve conduction study and somatosensory evoked potentials revealed that peripheral conduction deficit, often subclinical, was the commonest abnormality, and TR resulted in substantial improvement. Visual evoked potentials demonstrated subclinical impairment, which did not improve after TR. The brainstem auditory evoked potentials were essentially normal and unaffected by TR.

Experimental uremic neuropathy. Part 2. Sodium permeability decrease and inactivation in potential clamped nerve fibers

Potential recordings and potential clamp of isolated myelinated fibers from the sciatic nerve of acutely uremic rats showed a marked decrease in excitability related to a decrease in the specific Na permeability (P Na) of the nodal membrane. Mean value of the available P Na in the resting node of the uremic rats was 24% of the P Na in a control group. This change explained the decreased nerve conduction velocity in the acutely uremic rat. The Na current reversal potential was decreased in some fibers, reflecting an axoplasmic Na accumulation. The decrease in P Na was to a large extent caused by an increased inactivation, due to a negative shift (about 10 mV) of the steady state inactivation curve along the potential axis. The activation of P Na was similarly shifted (about 10 mV) to a more negative potential region. Such changes may be caused by elevated intracellular [Ca], suggesting a disturbance in Ca metabolism or an intracellular accumulation of cationic metabolites (which possibly have a similar effect) in rats with acute uremia.

Central and peripheral nervous system effects of chronic renal failure

Although neurologic dysfunction is a major cause of disability in patients with chronic renal failure, there is little knowledge of the underlying metabolic defect(s). We used a canine model to study the effects of chronic renal failure (CRF: 4 months after 1-7/8 nephrectomy, GFR 11 +/- 2 ml/min) on the composition and function of the nervous system. We also studied the effect of acute renal failure (ARF: 3.5 days after bilateral ureteral ligation) on peripheral nerve composition and function. In dogs with CRF for 4 months intracellular pH of brain and cerebro-spinal fluid (CSF) pH remained normal, despite metabolic acidemia. Osmotic equilibrium of the brain with plasma and CSF (and thus a normal water content) was maintained by almost equivalent increases in brain of urea and idiogenic osmoles (25 mmoles/kg H2O and 23 to 26 mOsm/kg H2O, respectively). Electrolyte concentration in brain tissue water did not change significantly. Calcium content was increased in cortical gray matter and hypothalamus of dogs with CRF, but was normal in the six other regions measured. Functional changes measured by the electroencephalogram were just as severe as those previously seen in dogs with ARF. The motor nerve conduction velocity (MNCV) was normal in dogs with ARF and did not change after up to 6 months of CRF.(ABSTRACT TRUNCATED AT 250 WORDS)

Statistical variation of nerve conduction velocity. An analysis in normal subjects and uraemic patients

The maximal nerve conduction velocity (NCV) of 6 sensory nerves (N. radialis, suralis and peronaeus superficialis, bilaterally) was determined in 88 normals and 59 uraemic patients. When the effect upon nerve conduction velocity of age and temperature was removed through partial correlations, it became possible to verify the negative correlation between the height of the patient and NCV. This explained as much as 35% of the remaining variance in males. There were also other significant differences in the nerve functions between the sexes. A set of "statistical corrections" (grouping of NCV's according to the subject's sex, computing of the average NCV's of an individual, and height-, age- and temperature normalization of single or mean NCV values) substantially decreased the variability of NCV. At the same time, the sensitivity of NCV measurement in the early diagnosis of nerve dysfunction caused by uraemia was increased. It is suggested that the results of NCV measurements should not only be reported as rough, absolute data, but also as normative values, taking into account the known physiological determinants.

Neuropsychiatric symptomatology with chronic renal insufficiency in the stage of compensated and decompensated retention. II. Peripheral nerve disturbances

80 strictly selected patients with chronic renal insufficiency with plasma creatinine values of 1.4-14.5 mg% were examined for clinical and electrophysiological signs of nephrogenic polyneuropathy. The motor symptoms complained of were cramps in 43.8% of the patients, "restless leggs" in 18.7%, muscular twitchings in 12.5%. It was emphasized that the first two symptoms do not always indicate the presence of polyneuropathy. 30% complained of paresthesias, 5% of "burning feet". The most frequent clinical finding was the impairment of vibration sense in the feet in 37.5% followed by diminshed appreciation of passive movement of the toes in 30%, weakening or absence of the ankle jerk in 23.8% and finally, weakening of the patellar reflex in 5%...