The Egyptian Journal of Neurology, Psychiatry and Neurosurgery

ORIGINAL ARTICLE
Year
: 2016  |  Volume : 53  |  Issue : 3  |  Page : 156--160

Normative data of ulnar nerve conduction studies at zagazig university hospitals: an egyptian study


Marwah A Hany Hammad1, Nillie Ezzeldin1, Abeer M El-Shafey1, Engy Mohammed Emad Soliman2,  
1 Department of Rheumatology and Rehabilitation, Faculty of Medicine, Zagazig University, Zagazig, Egypt
2 Department of Neurology, Faculty of Medicine, Zagazig University, Zagazig, Egypt

Correspondence Address:
Abeer M El-Shafey
Department of Rheumatology and Rehabilitation, Faculty of Medicine, Zagazig University, Zagazig 02055
Egypt

Abstract

Background An Egyptian normative database for ulnar nerve conduction studies (NCSs) considering the influence of age and sex is still absent. Objectives The aim of our work was to assess the normal variations of motor and sensory ulnar NCSs in a sample of normal Egyptian individuals at Zagazig University Hospitals. Methods This study was carried out at Zagazig University Hospitals on 110 individuals. Motor and sensory conduction studies of the ulnar nerve in the dominant hand were assessed. Results Motor latencies in male patients were longer than those in female patients and the difference was significant. No significant difference between male and female patients in any of the other ulnar nerve parameters was found. A significant positive correlation was found between age and motor latencies. Negative correlations were found between age and sensory amplitudes and with sensory conduction velocities. White collar workers had the slowest motor and sensory conduction velocities. Conclusion We conclude that age, sex, and occupation caused variability in ulnar NCSs in our studied group of normal Egyptians at Zagazig University Hospitals, but using the same reference data in patients of different ages and sex may result in inaccurate interpretation of ulnar NCSs, which is a common pitfall in our clinical practice.



How to cite this article:
Hany Hammad MA, Ezzeldin N, El-Shafey AM, Soliman EE. Normative data of ulnar nerve conduction studies at zagazig university hospitals: an egyptian study.Egypt J Neurol Psychiatry Neurosurg 2016;53:156-160


How to cite this URL:
Hany Hammad MA, Ezzeldin N, El-Shafey AM, Soliman EE. Normative data of ulnar nerve conduction studies at zagazig university hospitals: an egyptian study. Egypt J Neurol Psychiatry Neurosurg [serial online] 2016 [cited 2022 Dec 1 ];53:156-160
Available from: http://www.ejnpn.eg.net/text.asp?2016/53/3/156/193065


Full Text

 Introduction



Ulnar nerve conduction studies (NCSs) are one of the most commonly performed electrodiagnostic tests and are of great importance in the diagnosis and follow-up of ulnar nerve injuries and entrapments. Many factors such as age, sex, hand dominance, and race may affect the nerve conduction parameters during electrodiagnosis [1],[2]. Although ulnar NCSs are performed frequently in nearly every electrodiagnostic clinic in Egypt, an Egyptian normative database for this nerve and all other nerves is still absent.

Sex can affect NCSs; some studies suggested that women had slower conduction velocities compared with men [2],[3]. A recent study showed different results, where female patients had higher amplitude and faster conduction velocity in both motor and sensory stimulation of median and ulnar nerves, whereas motor and sensory latencies of median and ulnar nerves were longer in male patients [4].

NCS parameters are influenced by myelin maturation: as myelin matures, the conduction velocity increases. By the age of 3 years, most nerves have reached their maximum conduction velocity. The nerve conduction parameters remain stable until approximately age 30 and then begin to decline slowly [2],[5],[6].

Occupation may also influence nerve conduction parameters; for example, the use of computers during working hours involves continuous repetitive strokes, persistent wrist extension during typing, and complete pronation of the forearm for operation of the computer mouse, resulting in neural micro damage at the wrist region while the individual may have no obvious complaint [7].

The aim of our work was to assess the norms of motor and sensory ulnar NCSs in a sample of normal Egyptian individuals at Zagazig University Hospitals. We hypothesized the presence of variability between individuals of different ages, sex, and occupation regarding ulnar nerve latencies, amplitudes, and conduction velocities.

 Methods



This observational cross-sectional study was carried out at Zagazig University Hospitals on 110 individuals who attended our rheumatology outpatient clinic and volunteered to undergo ulnar NCS. The study included 91 women and 19 men with ages ranging from 18 to 67 years. Patients complaining of any tingling or numbness in the upper limbs were excluded from this study. Patients with ulnar nerve pathology, cervical spondylosis, cervical disc syndromes, thoracic outlet syndrome, diabetes or other endocrinal disorders, and autoimmune rheumatic diseases were all excluded from this study. The study was approved by the local ethics committe.

Electrophysiological studies of the ulnar nerve of the dominant hand were performed at room temperature using Nihon Kohden Neuropack S1 electromyography equipment (Japan). Stimuli with pulse duration of 0.10 ms for sensory nerve conduction and 0.20 ms for motor nerve conduction were applied over the ulnar nerve at the wrist until supramaximal responses were obtained.

The filter bandwidth was adjusted to 10 Hz and 5 kHz. The sweep speed was adjusted to 2 ms per division; and the sensitivity was adjusted to 20 µV and 5 mV per division for sensory and motor NCS, respectively.

Motor and sensory conduction studies of the ulnar nerve were assessed. Round plate surface disc electrodes were used for motor conduction studies, and ring electrodes were used for sensory conduction studies. Electrophysiological studies and normal reference values were evaluated according to the description of Preston and Shapiro [8].

For motor ulnar NCSs, the recording electrodes were placed over the abductor digiti minimi muscle. The active recording electrode was placed on the belly of the muscle and the reference electrode was placed on the tendon insertion. Motor conduction velocity (MCV in ms−1) of the forearm was assessed by stimulating the ulnar nerve at the wrist stimulation 80 mm proximal to the recording electrode, and at the elbow 10 mm below and 110 mm above the medial epicondyle. Compound muscle action potential (CMAP in mV) amplitude was measured peak to peak.

Sensory ulnar NCSs were performed using the antidromic method recording at the base of the fifth finger and stimulating at the wrist with a fixed distance of 13 cm; sensory distal peak latency was measured in ms and sensory conduction velocity (SCV) in ms−1, and sensory nerve action potential (in µV) amplitude was measured peak to peak.

Motor nerve conduction velocities were considered abnormal if below 49 ms−1. Distal motor latencies were considered prolonged if higher than 3.3 ms. SCV of the ulnar nerves was considered abnormal if below 50 ms−1. Peak latencies were considered abnormal if longer than 3.1 ms.

Statistical analysis

Data were analyzed using the SPSS software package, version 18.0 (SPSS Inc., Chicago, Illinois, USA). Quantitative data were expressed using range, mean, and SD, whereas qualitative data were expressed in frequency and percentage. Quantitative data were analyzed using the Mann–Whitney test and Spearman’s coefficient. The P value was assumed to be significant at 0.05 or less.

 Results



This study included 110 individuals, including 91 women and 19 men. Their ages ranged from 18 to 67 years with a mean of 36.264±11.073 years. [Table 1] shows the range of normality in our studied group. Motor latencies in men were longer than in women and the difference was significant (P<0.01), as shown in [Table 2]. No significant difference between men and women was found in any of the other ulnar nerve parameters.{Table 1}{Table 2}

[Table 3] shows a significant positive correlation between age and motor latencies (P<0.01): older age was associated with longer motor latencies. Negative correlations were found between age and sensory amplitudes (P<0.001) and also sensory conduction velocities (P<0.01) as older age was associated with smaller sensory amplitudes and slower conduction velocities. Negative correlations with motor amplitudes and conduction velocities did not reach statistical significance. Normal values of ulnar nerve parameters in different age groups are represented as mean and SD in [Table 4].{Table 3}{Table 4}

[Table 5] shows a significant difference between individuals with different occupations regarding ulnar nerve motor latency and MCV and SCV. Post-hoc tests revealed that the unemployed had significantly shorter motor distal latencies (P<0.001), whereas white collar workers had significantly slower motor conduction velocities (P<0.05) and sensory conduction velocities (P<0.001).{Table 5}

 Discussion



Normal values of the ulnar NCSs vary. Many factors are responsible for this variability [1],[2]. Age, sex, and ethnicity are the important ones [3]. The aim of this study was to assess the norms of motor and sensory ulnar NCSs in a sample of normal Egyptian individuals at Zagazig University Hospitals, including the influence of age, sex, and occupation.

In this study, men had longer motor latencies than women. The reason behind this finding may be the greater height and limb length of the male volunteers. Thakur and colleagues in a sex-based study on healthy individuals similarly showed that latencies of all studied nerves of the upper limbs were longer in men than in women. They also found that men had larger CMAP amplitudes, whereas sensory nerve action potential amplitudes were larger in women. They finally concluded that sex has definite effects on NCS variables [9]. In contrast, Jagga et al. [6] and other previous studies found no significant effect of sex on nerve conduction measures [10],[11].

Maher et al. [12] studied median nerves in an Egyptian population and stated that CMAP amplitudes in the median nerve were larger in men probably because of the larger muscle mass and motor unit size. However, ulnar motor and sensory amplitudes and conduction velocities in our study did not show any significant difference between men and women. This variability indicates that these effects may not be identical in different nerves.

In this study there were significant correlations between age and ulnar nerve parameters. There was a positive correlation with motor latencies and a negative one with sensory amplitudes and conduction velocities. According to Kimura [13], NCS parameters change with age. Tong et al. [14] and Huang et al. [15] studied nerve conduction parameters in both median and ulnar nerves in relation to age. The results were similar to ours regarding the ulnar nerve [14],[15]. Other studies like that of Awang et al. [1] investigated median, ulnar, and sural nerves in an Asian population and revealed no significant effect of age on nerve conduction velocities except for median MCV, supporting the concept that even the influence of age on nerve conduction parameters differs between different populations.

In this study the unemployed had significantly shorter motor latencies, denoting that they were less liable to microtraumas compared with blue and white collar individuals. No significant difference was found between blue and white collar workers regarding motor and sensory latencies, as, although white collar workers have less strenuous tasks, computer use is more frequent in these individuals. White collar individuals also showed significantly slower motor and sensory conduction velocities compared with blue collar workers. Repetitive movements in computer use causes friction, which may lead to inflammatory changes and nerve compression with subsequent mechanical disruption of vascular perfusion of the nerve. Increased intraneural pressure also leads to edema, which causes further compression especially at joints and bony prominences leading to axonal and myelin sheath disruption, which varies according to the magnitude of pressure and duration of working hours. This, in turn, increases the distances between the nodes of Ranvier and interferes with impulse transmission, thus decreasing conduction velocity, and if compression continues axonal demyelination and degeneration occurs with subsequent neural fibrosis [16].

The limitation of our study is that this is a single-centre study that was carried out on a small group of Egyptians. The need for a huge multicentre study is necessary to set an Egyptian database for ulnar nerve normal values.

We conclude that age, sex, and occupation were found to cause variability in the parameters of ulnar NCSs in our studied group of normal Egyptians at Zagazig University Hospitals. Using the same reference data in patients of different ages and sex may result in inaccurate interpretation of ulnar NCSs, which is a common pitfall in our clinical practice. Also different populations should have different reference databases, hence making the development of a normative reference database of all studied nerves in the Egyptian population necessary considering the influence of age, sex, and occupation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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