|Year : 2015 | Volume
| Issue : 1 | Page : 13-19
Clinical profile of diabetic sensorimotor polyneuropathy in a tertiary hospital in Northwestern Nigeria
Aliyu Ibrahim1, Lukman F Owolabi1, Musa M Borodo1, Adesola Ogunniyi2
1 Department of Medicine, Bayero University Kano and Aminu Kano Teaching Hospital, Kano, Nigeria
2 Department of Medicine, Division of Neurology, University College Hospital Ibadan, Ibadan, Nigeria
|Date of Web Publication||8-May-2015|
Department of Medicine, Bayero University Kano/Aminu Kano Teaching Hospital, PMB 3452, Kano
Source of Support: None, Conflict of Interest: None
Objective: To determine the frequency, severity, and determinants of diabetic sensorimotor polyneuropathy (DSPN) in adults from a tertiary hospital in Northwestern Nigeria. Materials and Methods: A cross-sectional hospital-based study where 400 type 2 diabetes mellitus patients attending clinic in a tertiary hospital were screened for DSPN and graded for severity using the United Kingdom screening test (UKST). Logistic regression was used to identify independent predictors of DSPN after controlling for other covariates. All data were analysed using Predictive Analysis Software (PASW) version 18.0 for Windows (SPSS Inc., Chicago, IL, USA). Results: Frequency of DSPN among the study (comprising 59 males and 66 females) subjects was 125 (31.2%), of which 105 (26.3%) patients were symptomatic. Sixty-eight (17%) patients were at high risk of developing diabetic feet ulceration. Multivariate logistic regression showed that marital status (OR = 0.55; 95% CI = 0.31-0.98) was protective, while the duration of diabetes (OR 5.80; 95% CI = 3.38-9.95) was a significant independent predictor of DSPN. Conclusions: The high frequency of DSPN in patients with high risk of feet ulceration from this study prompt the need to adopt efficacious and less-expensive strategies for screening and preventing diabetic foot complications in our resource-constraint settings.
Keywords: Clinical profile, diabetes mellitus, sensorimotor polyneuropathy
|How to cite this article:|
Ibrahim A, Owolabi LF, Borodo MM, Ogunniyi A. Clinical profile of diabetic sensorimotor polyneuropathy in a tertiary hospital in Northwestern Nigeria. Niger J Basic Clin Sci 2015;12:13-9
|How to cite this URL:|
Ibrahim A, Owolabi LF, Borodo MM, Ogunniyi A. Clinical profile of diabetic sensorimotor polyneuropathy in a tertiary hospital in Northwestern Nigeria. Niger J Basic Clin Sci [serial online] 2015 [cited 2023 Feb 1];12:13-9. Available from: https://www.njbcs.net/text.asp?2015/12/1/13/156669
| Introduction|| |
Diabetic neuropathy (DN) is a frequent microvascular complication of diabetes mellitus (DM), and represents an insidious process for which a disconnection may exist between development of symptoms and signs, and its pathological severity. 
It has a spectrum of both clinical and subclinical syndromes that have variable underlying pathogenetic mechanisms characterised by diffuse or focal damage, to peripheral somatic or autonomic nerve fibres. The more common diffuse neuropathies includes diabetic sensorimotor polyneuropathy (DSPN) and diabetic autonomic neuropathy, which usually have a chronic and progressive course.  Diabetic sensorimotor polyneuropathy is the most common clinical subtype seen in clinical practice. It is potentially the most debilitating, as many of the patients are often asymptomatic, placing them at high risk of developing devastating foot complications before they present with overt symptoms of diabetes. 
It is also the leading cause of non-traumatic limb amputation globally amongst patients with diabetes, resulting in prolonged hospital stay and a presumable increase in their morbidity and mortality. 
Clinical practice guidelines recommend annual screening for neuropathy in all patients with diabetes, as part of their routine assessment for complications, which offers them the opportunity to actively alter the course of suboptimal glycaemic control, as there is increasing evidence that even pre-diabetic states may be associated with some form of neuropathy. 
Inadequate or sometimes total lack of foot care programmes in our existing health care settings is a considerable barrier to the management of patients with DSPN in Nigeria, ,, although it has been shown to significantly reduce amputation rates even in resource-poor countries without the need for expensive equipment. ,
Screening tools like the United Kingdom screening test (UKST), which has been validated in Nigeria at the time of our study, may provide a simple clinical criterion for detecting DSPN without recourse to highly sophisticated and expensive electrodiagnostic procedures. 
Other qualitative life tools have previously been used to assess the severity of DSPN in several studies; however, the subjectivity of patients' responses was a major drawback making them less likely to be useful when compared to composite scoring systems with more objective signs. ,
Quantitative assessment of DSPN severity by staged or continuous approaches is highly recommended, with the electrodiagnostic studies component recommended mainly in monitoring disease patterns in clinical research protocols. 
The paucity of regional data on the prevalence and risk factors for DSPN prompted this study with the aim of identifying and thereby preventing associated secondary complications, consequently improving quality of life for DM patients in our resource constraint setting.
| Materials and methods|| |
The study was conducted over a period of six months in the Endocrine and Metabolism Clinic of Aminu Kano Teaching Hospital, Kano located in Northwestern Nigeria. The Hospital Ethics committee gave ethical approval for the study.
Subjects recruited were consenting type 2 adult patients, diagnosed to have DM for a duration of at least six months, and/or were not on insulin treatment within two years after DM diagnosis (WHO 1999 Diagnostic Criteria). 
Patients with current foot ulcer at the time of study, past history of stroke, peripheral nerve or vascular disease, limb surgery, history of exposure to known neurotoxins e. g., treatment for tuberculosis or cancer, leprosy, myelopathies, or known organ failure (renal, hepatic, cardiac, respiratory) were excluded from the study.
Information (after a pre-testing at the GOPD) on socio-demographic variables, blood pressure, BMI, fasting blood glucose measurements, presence of retinopathy and/or proteinuria, and the UKST score was obtained using a semi-structured interviewer-administered questionnaire. The UKST score is a two-part diagnostic test comprising symptoms scores (abnormal sensation, site of discomfort, time of worst symptoms, and alleviating factors) and signs scores (ankle reflex, pain sensation, vibration sense, and temperature perception). The symptom scores have a maximum of 9 points, while the sign scores have a maximum of 10 points.
Frequency of DSPN was determined using the following diagnostic criteria:(i) At least a moderate sign score (6 points) if asymptomatic or (ii) mild signs score (3 points) with a moderate symptom score (5 points).
The severity of DSPN was further assessed by grading the neuropathy sign scores, and patients with scores of 8 and above were assigned to the high risk of feet ulceration group.
The investigators further examined for association factors using a nested case-control approach where patients with DSPN were considered as study cases, while those without as controls.
Blood pressure measurement was done twice for each patient (five minutes apart) in a sitting position using the right arm and an appropriate-sized cuff (Accoson (R) mercury sphygmomanometer).
Height and weight were measured using a stadiometre and weighing scale (Seca®), respectively for all the patients. Direct ophthalmoscopic examination to detect the presence of diabetic retinopathy was done in all the patients using a Keeler® ophthalmoscope in a darkened room after instilling 2 drops of a mydriatic solution (1% Tropicamide) to dilate the difficult to examine pupils, and after ascertaining that the patient does not see haloes around lights to exclude symptoms of raised intraocular pressure.
Blood was analysed for fasting plasma glucose in the clinic using Accuchek-Active glucometer (glucose oxidase method) and urinalysis for proteinuria using Combi-9® urine dipsticks (tetrabromophenol blue) as per the manufacturer's protocol, which has a minimum sensitivity of 10 mg protein/dl urine. The colour fields corresponded to the following ranges of albumin concentrations: Negative, 1+ (30 mg/dl), 2+ (100 mg/dl) and 3+ (500 mg/dl).
The ankle (Achilles tendon) reflexes were examined using a flexible tendon hammer with the foot passively positioned and dorsi-flexed slightly to obtain optimal stretch of the muscle and the Achilles tendon percussed directly. Normal reflexes were graded as 0 point, present with reinforcement as 1 point, and absent as 2 points for each foot.
Pain was elicited after informing the patient about the procedure, using the tip of a disposable pin applied perpendicularly to the dorsum of the big toe with the eyes closed. This was repeated on the dorsum of the hand, and if the sensation of the foot was more sensitive (hyperaesthesia) or less sensitive (hypoaesthesia), it is graded as 1 point or if it is comparable to that felt on the hand graded as 0 point.
Vibration sensation was tested using a 128 Hz tuning fork placed over the dorsum of the great toe on the bony prominence of the interphalangeal joint bilaterally, with the eyes closed. This was repeated immediately on the dorsum of the wrist, and the patient asked to compare the strength of vibration at the two sites. No vibration felt or if it felt stronger at the wrist was graded 1 point and if the vibration was same at the wrist and hallux graded as 0 point. A sham test when the tuning fork was not vibrating was performed to be certain that the patients were responding to vibration, and not pressure, or some other sensory cues.
Temperature sense was assessed using test tubes filled with warm water or cracked ice, which was placed on the pulp of the hallux with the eyes closed. Normal temperature sense was graded as 0 point and abnormal temperature sense (patient perceived the cold test tube as warm or vice-versa or unable to tell) graded as 1 point.
Frequency and descriptive statistics were used to examine the general characteristics of the subjects. Cochran's and Mantel-Haenszel statistics were used to estimate the odds ratio (OR) and 95% confidence interval (CI) for potential risk variables. Pearson Chi-squared test was used to compare categorical variables.
Multiple logistic regression analysis was constructed with the use of factors significant on univariate comparisons to further evaluate for independent predictors, while controlling for possible covariates.
All data were analysed using PASW version 18.0 for Windows (SPSS Inc., Chicago, IL, USA). Data were expressed as mean values ± standard deviation unless otherwise stated. Statistical significance for the analysis was set at P < 0.05.
| Results|| |
During the study period, 400 consenting adult outpatients (177 men, 223 women) with clinical diagnosis of type 2 DM were enrolled. The mean (SD) age of all the patients was 52.9 ± 10.2 years (age range of 33-74 years). Three hundred and twenty-four (81.0%) resided in an urban setting, and 265 (66.3%) were fully employed (mainly civil servants or self-employed, engaging in farming or trading activities). Majority of the subjects (n = 325; 81.3%) were married, and 169 (42.2%) had some formal education (denoting any certified form of education). The mean (SD) weight and height of the patients were 75.01 ± 16.06 kg and 169 ± 6 cm, respectively with a BMI of 26.1 ± 4.7. The mean age and duration of DM onset were 47.34 ± 9.32 and 5.57 ± 3.06 years respectively. Additionally, the mean (SD) blood pressure was 137.42 ± 20.39 (systolic) and 83.31 ± 9.42 (diastolic), with fasting blood glucose of 9.48 ± 7.59 mmol/litre.
One hundred and six patients (26.4%) had moderate symptom scores of 5 points and above, signifying symptomatic DSPN, and 120 (30.0%) patients had moderate sign scores of 6 and above, signifying more objective features of DSPN [Table 1].
The overall frequency of DSPN from the study was 125 (31.2%), and comprised 59 males and 66 females. Sixty-eight (17.0%) patients with DSPN (27 males and 41 females) were at high risk of developing feet ulceration by having a UKST sign score of 8 points or more. Furthermore, the scores were less than 8 points for 109 patients (87.2%), indicating a less likelihood of developing this sinister complication [see [Table 2].
The potential variables shown to be associated with DSPN after univariate analysis included; the age at onset of DM (OR = 1.97, 95% CI = 1.14-3.40), educational status (OR = 0.46, 95% CI = 0.29-0.72), duration of DM (OR = 6.30, 95% CI = 3.73-10.66), marital status (OR = 0.45, 95% CI = 0.27-0.74), retinopathy (OR = 2.04, 95% CI = 1.25-3.32), and proteinuria (OR = 1.89, 95% CI = 1.22-2.93). These variables were further subjected to multivariate logistic regression analysis considering that they can affect the nerves simultaneously [see [Table 3] and [Table 4].
Marital status (OR 0.55, 95% CI = 0.31-0.98, P = 0.042) and duration of diabetes (OR = 5.80, 95% CI = 3.38-9.95, P < 0.001) were shown to be significant independent predictors of DSPN, with the former being protective, and the latter a risk [see [Table 5].
|Table 4: Other factors associated with diabetic sensorimotor polyneuropathy |
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| Discussion|| |
The frequency of DSPN in adults with type 2 diabetes was 31.2%. This figures compares well with reports from earlier studies from the United Kingdom using a similar tool and diagnostic criteria.  Earlier reports from Nigeria by Unachukwu et al.,  and Ugoya et al.,  showed significantly higher rates; however, the former selected patients with foot ulcer/gangrene while the latter used another screening tool probably explaining the differences. Our frequency was also similar to rates reported from Sudan, Egypt, Bahrain, United Arab Emirates, Portugal, Spain, and the San Luis valley study in Southern Colorado in the United States. ,,,,,, However, using similar diagnostic criteria, rates from Iran were lower, which may probably be a reflection of the system of health care given or other less plausible constitutional explanations. 
Informal educational status was found to be negatively associated with polyneuropathy, as significant number of patients lacked formal education. This is in contrast to reports from parts of Southwestern Nigeria  and the Middle East,  where formal education was shown to improve access to health care, in addition the direct impact on health seeking behaviour and compliance to treatment.
Marital status was shown to be protective among the study population in concordance with previous studies.  This observed protective effect of marriage appeared to be consistent with reports that linked better knowledge and practise of health care to family and income levels, and probable buffering effect on stress, which may lead to reduced activation of the neuroendocrine system, and therefore reduction in atherosclerosis.  It is also possible that the reinforcement of the family on compliance to treatment may be an explanation.
The study also showed that the frequency of DSPN increased steadily with increasing duration of diabetes from 18.7% in those with less than five years of diabetes prior to investigation to 48.2% in those with more than five years of diabetes, which is consistent with most studies assessing duration as a risk factor. ,,
Retinopathy an important microvascular complication of DM, was found to be associated with neuropathy from the study, which corroborates findings of other studies that have reported it as an important risk factor in their analysis. , However, it was not shown to be a predictor of DSPN after logistic regression in our study. It may be just a reflection of similar microvascular event in the vasa nervorum, which contributes to peripheral nerve damage.
Proteinuria was positively associated with DSPN in this study, as 40.6% of subjects had co-existing renal impairment. Although less sensitive test than microalbuminuria, which is a marker for early renal endothelial damage, dipsticks may be a readily available useful screening tool for proteinuria especially in our resource-challenged settings. 
In this study, neuropathy was neither shown to be related to smoking nor alcohol intake, as most subjects were non-smokers or did not have significant alcohol intake history. This finding was comparable to findings by Booya et al.,  who probably have a similar socio-cultural setting where there may be a general denial of alcohol ingestion due to its negative societal implications or religious connotation, making a critical analysis of the possible association of these variable with neuropathy difficult. However, studies done elsewhere have shown a strong association between smoking, alcohol abuse and neuropathy. 
The mean systolic and diastolic blood pressures of the patients in the study were not associated with neuropathy, although most previous studies have reported a direct relationship between hypertension and neuropathy. , This is probably because of effect of anti-hypertensive treatment, making it difficult to infer on any association with neuropathy in our study.
The study showed significant number of patients with moderate polyneuropathy when rated on the composite UKST sign score, who may eventually progress to severe polyneuropathy if preventive measures are not instituted, thereby placing them at a higher risk of developing feet ulcerations, and subsequent amputations.
This finding is a clarion call for regular assessment for DSPN in the setting of this study as stipulated in standard treatment guidelines for DM. Quality of life scores have been used to assess the severity of DSPN previously; however, the subjectivity of patients' responses to pain and other symptoms makes it a less likely a useful tool to assess severity when compared to scoring tools with objective signs. 
Our findings should be interpreted within the limitations of being cross-sectional and its hospital based nature, where presumably no inferences on the cause and effect could be drawn as the study population may likely comprise of more advanced disease cases.
There is the need for larger multi-centre population-based prospective studies or even community-based studies to assess the magnitude of DSPN and its risk factors in our environment. This should aim towards developing a national guideline for its diagnosis and optimal management, consistent with our local needs and capabilities, similar to what obtains in other resource challenged countries.
In conclusion, the frequency of DSPN from our study prompts the need to adopt strategies of careful screening of patients in the diabetes clinic, education of these patients and other health professionals, and the institution of preventive measures. These may help to reduce the burden of ulcerations and amputations, and the socio-economic impact of its morbidity and mortality amongst DM patients in Nigeria.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]