ORIGINAL CONTRIBUTION Prevalence of Ulnar Neuropathy in Patients Receiving Hemodialysis Rachel Nardin, MD; Kristine M. Chapman, MD; Elizabeth M. Raynor, MD Background: Ulnar neuropathy can cause pain, weak- Results: Clinically evident, electrophysiologically con- ness, and sensory changes in the hand and can result in firmed ulnar neuropathy was present in 37 (51%) of the functional impairment. Patients with end-stage renal dis- 73 subjects with both screening and nerve conduction ease receiving hemodialysis may be predisposed to ul- study data available. The true prevalence of ulnar neu- nar neuropathy by factors such as arm positioning dur- ropathy in this cohort was estimated between 41% ing hemodialysis, underlying polyneuropathy, and upper and 60%. extremity vascular access. Conclusions: There is a high prevalence of ulnar neu- Objective: To determine the prevalence of clinically evi- ropathy in patients with end-stage renal disease receiving dent ulnar neuropathy in a cohort of 102 patients with end-stage renal disease receiving hemodialysis. hemodialysis, which has not been previously recognized. The high prevalence of ulnar neuropathy in this popula- Design: All eligible patients in a single dialysis unit were tion suggests that preventative efforts are indicated to pre- screenedforsymptomsandsignsofulnarneuropathy.Those vent this functionally limiting complication. with at least 1 symptom or sign underwent nerve conduc- tion studies to confirm the presence of ulnar neuropathy. Arch Neurol. 2005;62:271-275 LNAR NEUROPATHY CAUSES weakness and sensory changes in the hand and pain in the elbow and dis- tal arm. Untreated ulnar Uneuropathy can lead to an ulnar “claw hand” with functional impairment. The ul- nar nerve is prone to injury at the elbow, where it is subject to mechanical stretch and compression owing to its location in the ulnar groove. Risk factors for ulnar neuropathy include repetitive flexion of the elbow and sustained external pressure on Figure 1. Typical patient position during dialysis; the the ulnar groove. Individuals with poly- ulnar nerve is vulnerable to compression against the neuropathy appear more likely to de- armrest. velop secondary compressive mononeu- ropathies.1 in the arm. The hemodynamic effects of Patients with end-stage renal disease vascular access or the repeated inflation (ESRD) receiving hemodialysis may be at of a blood pressure cuff during hemodi- increased risk for ulnar neuropathy. They alysis may lead to ischemia of peripheral often have underlying polyneuropathy nerves, increasing their vulnerability to from uremia2,3 or diabetes.1 Patients re- compression.4-7 Lastly, tumoral calcino- Author Affiliations: ceiving hemodialysis spend many hours sis,8 amyloid deposition,9,10 and expanded Department of Neurology, Beth sitting in a dialysis chair with the fore- extracellular fluid volume11 may also affect Israel Deaconess Medical arm typically pronated so that the cubital peripheral nerves in this population. Center, Boston, Mass (Drs Nardin and Raynor); and tunnel is in contact with the flat surface Estimates of the prevalence or inci- Division of Neurology, of the arm rest; this may lead to compres- dence of ulnar neuropathy in the hemo- University of British Columbia, sion of the ulnar nerve (Figure 1). Many dialysis population range from 1% to 19%, Vancouver, British Columbia patients receive hemodialysis through an with the higher figures including asymp- (Dr Chapman). arteriovenous fistula or a synthetic graft tomatic subjects.11,12 Based on our expe- (REPRINTED) ARCH NEUROL / VOL 62, FEB 2005 WWW.ARCHNEUROL.COM 271 ©2005 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/28/2021 Table 1. Electrophysiologic Criteria Total Hemodialysis Unit Population (N = 102) Ulnar Neuropathy—Any of the Following: 1. Ն10-m/s drop in ulnar MCV across the elbow 2. Ulnar MCV across the elbow Ͻ45 m/s (with a normal median MCV) Not Eligible (n = 12) Screening Interview and Examination (n = 90) 3. Ulnar SNAP Յ12 uV (with a normal median or radial SNAP) 4. Ulnar CMAP Ͻ5 mV (with a normal median CMAP) A. Mild to moderate: ulnar CMAP Ͼ3mV Յ Ͻ Signs or Symptoms No Signs or Symptoms B. Moderate to severe: ulnar CMAP 3mVor ulnar SNAP 5uV of Ulnar Neuropathy (n = 62) of Ulnar Neuropathy (n = 28) with a radial SNAP Ն12 uV Median Neuropathy at the Wrist—Any of the Following: 1. Median DML absent or prolonged in relation to ulnar DML by Ն Complete Incomplete Refused 1.5 ms NCS (n = 45) Data (n = 1) Consent (n = 16) 2. Median DML prolonged in relation to ulnar DML by Ն1msona lumbrical/interosseous study 3. Median SNAP absent (if no polyneuropathy) or prolonged in Figure 2. Study flow diagram. NCS indicates nerve conduction study. relation to ulnar SNAP by Ն1ms A. Mild to moderate: median CMAP Ն 2.5 mV B. Moderate to severe: median CMAP Ͻ2.5 mV or median SNAP ELECTROPHYSIOLOGIC STUDIES Ͻ5 uV with radial SNAP Ն12 uV Polyneuropathy: Board-certified electromyographers performed all NCSs using Radial SNAP amplitude Ͻ12 uV and ulnar + median MCV Ͻ48 m/s a Synergy electromyograph (Oxford Instruments, New York, A. Mild to moderate: best radial SNAP 4.1-12 uV NY). We studied only subjects’ arms with symptoms or signs. B. Moderate to severe: best radial SNAP Յ4uV We performed the following studies: antidromic sensory NCS of the ulnar nerve (recording digit V), the median nerve (re- Abbreviations: CMAP, compound muscle action potential; DML, distal cording digit II), and the superficial radial nerve (recording at motor latency; MCV, motor conduction velocity; SNAP, sensory nerve action the snuff box); and motor NCS of the median nerve (record- potential. ing abductor pollicis brevis) and the ulnar nerve (recording ab- ductor digiti minimi), performed with the elbow in 70° to 90° of flexion. The electromyographer performed a second lumbrical- rience, we hypothesized that the prevalence of ulnar neu- first palmar interosseous comparative study if needed to clarify ropathy in patients receiving hemodialysis is greater than the presence of a median or ulnar nerve lesion at the wrist. previously recognized. Chronic ulnar nerve compres- Table 1 summarizes the electrophysiologic criteria used sion may not cause pain or tingling and thus may be over- to define ulnar neuropathy, median neuropathy, and polyneu- looked until weakness is profound, particularly in pa- ropathy. The criteria we used were stricter than the standard diagnostic criteria used in the BIDMC Electromyography Labo- tients with multiple medical problems. The identification ratory to minimize false-positive diagnoses. of hemodialysis as a risk factor for ulnar neuropathy would have clinical implications because this functionally lim- STATISTICAL ANALYSIS iting complication is potentially preventable. We under- took to determine the prevalence of clinically evident ul- Comparisons of demographic variables between subjects with nar neuropathy in a cohort of patients receiving and without ulnar neuropathy were made using unpaired t tests. hemodialysis. Analysis of the relationship between ulnar neuropathy and sub- ject risk factors used the ␹2 test of significance. All analyses were performed using StatView statistical software (SAS Institute, METHODS Cary, NC). SUBJECTS RESULTS We studied all patients receiving hemodialysis at Gambro Healthcare in Brookline, Mass, during a 3-week period in SUBJECTS March 2003. We screened all patients for eligibility and in- cluded those older than 18 years receiving hemodialysis for at During the study period, 102 patients received hemodi- least 3 months, who were medically stable and able to give in- alysis at Gambro Healthcare. Figure 2 illustrates the flow formed consent. The Beth Israel Deaconess Medical Center through the study of these individuals. Twelve patients (BIDMC) Committee on Clinical Investigation approved this did not meet inclusion criteria. We screened the remain- protocol, and we obtained written informed consent from all ing 90 subjects for symptoms or signs of ulnar neuropa- subjects. thy. Table 2 summarizes the clinical characteristics of We screened each eligible subject for symptoms or signs sug- this cohort. gestive of ulnar neuropathy. Symptoms of ulnar neuropathy were defined as (1) numbness or tingling in the fifth finger, (2) sub- jective hand weakness, or (3) pain in the elbow, medial fore- ELECTROPHYSIOLOGIC FINDINGS arm or hand, or fifth digit. We looked for signs of ulnar neu- ropathy, defined as (1) atrophy of the first dorsal interosseous Of the 90 subjects, 62 (69%) had at least 1 symptom or muscle, (2) weakness of the finger spreaders, or (3) reduced sign suggestive of ulnar neuropathy in 1 or both arms perception of pinprick over the fifth finger compared with the and were thus eligible for NCSs. Complete NCS data were index finger. All subjects with at least 1 symptom or sign were available for 45 (72%) of these 62 subjects. The NCS re- eligible to proceed with nerve conduction studies (NCSs). sults confirmed the suspected ulnar neuropathy in 37 (REPRINTED) ARCH NEUROL / VOL 62, FEB 2005 WWW.ARCHNEUROL.COM 272 ©2005 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/28/2021 Table 2. Clinical Characteristics of the Study Cohort* Subjects With Subjects Without All Eligible Subjects Ulnar Neuropathy Ulnar Neuropathy Characteristic (n = 90) (n = 37) (n = 36) Age, mean (range), y 61.2 (25-96) 63.4 (39-88) 54.8 (25-96) Male 39 (43) 16 (43) 17 (47) Female 51 (57) 21 (57) 19 (53) Duration of