Sciatica is a potentially debilitating ubiquitous condition. It is a common diagnosis in patients seen in neurology and primary care consultations . This pain originating from the back radiates in the pelvic limb through L5 or S1 spine segment. It settles down as a result of disco-radicular conflict between L4 and L5 or L5 or S1. Sciatica diagnosis is mainly clinical. Plain radiography and, computed tomography (CT) and magnetic resonance imaging (MRI) are used to assess sciatica etiology. Herniated disc is the major cause of severe, chronic or recurrent lower back pains  .
Frequency of sciatica in the general population ranges from 14% to 45% . In France, it is estimated between 5% and 10% . In sub-Saharan Africa, particularly in Nigeria, 16.4% of the general population suffered from sciatica in 2007 . In Benin, in a study conducted between 1994 and 1996 by AVIMADJE et al., sciatica accounts for 10.1% of rheumatic diseases in patients seen in consultation at CNHU-HKM Cotonou . Occupation-based analysis helps to determine occupation-related physical, psychological and personal risk factors associated with sciatica .
In Benin, few studies were conducted on sciatica in hospital setting. However, no research has ever been carried out in neurology department, though the unit handles a significant proportion of sciatica cases. Hence, this study was initiated and conducted so as to fill this gap. The key objective was to assess the epidemiological, clinical and etiological aspects of sciatica in the neurology department of Hubert Koutoukou Maga (HKM) Teaching Hospital (CNHU) in Cotonou.
2. Study Methods
It was a cross sectional, prospective, descriptive and analytical study conducted from 1st January 2016 to 30th June 2016 in the University Clinic of Neurology, CNHU HK Maga of Cotonou on sciatica patients seen in consultation over the study period. All patients meeting the inclusion criteria were systematically included in the study. Individuals excluded comprised patients with no complaints of sciatica, patients unable to describe the complaint and those who declined taking part in the study. Data collection was carried out through a standard information sheet with socio-demographic, clinical, para-clinical, and etiological data. Epi data 3.1 was used for data entry and Stata 11 for processing.
One hundred and fifteen patients were systematically included in the study.
Overall, of 618 patients seen in consultation during the study period, 115 (18.6%) individuals including 44 men were involved in this study. Their age ranged from 29 to 73 years with 52 +/− 16 as mean value. Individuals aged 40 to 59 and those over 60 years of age were in highest proportion i.e. 49.6% and 27.8% respectively. The respondents’ features are highlighted in Table 1.
Of the 115 respondents, 61 (53.1%) suffered from bilateral sciatica, 32 (27.8%) right lateral sciatica and 22 (19.1%) left lateral sciatica. The pain was topographically bilateral (L5 and S1) with 51 individuals (44.4%), unilateral L5 with 34 individuals (29.6%) and unilateral S1 with 13 patients (11.3%). The development of sciatica was acute (<1 month), sub-acute (1 - 3 months) and chronic (>3 months) in 20%, 14.8% and 65.2% of cases respectively. Patients reported severe (53%), mild (31.3%), light (4.4%) and normal (11.3%) pain. Prolonged standing and prolonged sitting were the most common triggering factors in 19.1% and 18.3% of the cases respectively. Twenty-eight patients (24.3%) reported increased pain during prolonged standing followed by 26 patients (22.4%) during prolonged sitting and 26 (22.4%) when walking. Supine position was the most relieving factor in 51 patients (44.4%). Paresthesia stands out as the most commonly associated symptom (59.1%), followed by intermittent claudication (40.9%), sphincter disorders (03.5%) and muscleatrophy (02.6%). The physical examination revealed Doorbell sign in 49 patients (42.6%), positive straight leg raising test in 63 individuals (54.8%) with 13% of them feeling pains at an angle below 30˚ and 31.3% when an angle is above 60˚. Over half patients (51.3%) had a Lasègue sign between 30˚ and 60˚. Plain radiography was the most performed paraclinical examination: 63 patients (54.78%), followed by lumbar spine CT scan with 21 patients (18.26%). The clinical and paraclinical features of these individuals are highlighted in Table 2 and Table 3. Degenerative injuries account for the major etiology in a proportion of 47%. These statistics are summarized in Figure 1. Sex was the only feature significantly associated with sciatica (p = 0.020). Age, occupation, level of education and BMI were not associated with sciatica, p = 0.293; p = 0.363; p = 0.819; p = 0.211 respectively.
Factors associated with the onset of sciatica in this study are summarized in Table 1.
Table 1. Respondents’ socio-demographic features, Cotonou, 2016.
Table 2. Respondents’ functional and clinical features, Cotonou 2016.
Table 3. Respondents’ clinic-physical features, Cotonou 2016.
Figure 1. Sciatica patients classification according to etiological data, Cotonou, 2016.
Frequency of sciatica in CNHU-HKM of Cotonou was 18.6%.
The literature highlights wide variability in frequency of sciatica in hospital setting   . In Benin, AVIMADJE et al. reported in 1999 that, sciatica accounted for 10.1% of rheumatic diseases in patients seen in consultation at CNHU-HKM . In Nigeria, 16.4% of the general population suffered from sciatica in 2007. Therefore, our study result was higher than records reported in the literature. This leads to the conclusion that sciatica is becoming increasing prevalent with time. Postures adopted at worksations, prolonged sitting, prolonged standing, jerking on motorcycle due to poor roadconditions affect the frequency of sciatica.
The study population age ranged from 29 to 73 years, with 52 ± 16 as mean value. Respondents aged 40 to 59 and those above 60 were prevalent, representing 49.6% and 27.8% respectively. These results show that sciatica affects both the youth and the elderly. The working population is the most vulnerable to this medical condition, as a result of poor postural hygiene in daily and professional tasks. MILLOGO  Bobo-Dioulasso reported 46 asmeanage, which is slightly lower than ours. In France, CURRALADAS  noted that the most affected age range was 40 - 50 years, with extremes values ranging from 18 to 76 years. Thus, sciatica mostly affects the middle-aged population, primarily those in their forties and sixties.
In our study, females outnumbered males, with an estimated sex ratio (M/F) of 0.6.
Other authors also noted female prevalence: AVIMADJE et al.  and MIJIYAWA et al.  with a sex ratio of 0.69 and 0.7 respectively. Such female prevalence of sciatica could be explained by a number of factors, especially household chores, maternity, overweight and development of women related work.
No sex prevalence was reported in the studies conducted by VALLS et al. . However, DELACAMBRE et al.  VALAT et al.  outlined male prevalence of sciatica and explained it by the fact that men put more strain on their spine in their daily activities and behaviors.
In our study, sciatica affected several sectors of activities, chiefly housewives and office clerks. This observation can be justified by the constraints of household chores which require adopting awkward postures, resulting in gradual degeneration of the spine. Similarly, for office clerks, prolonged sitting is a cause of dorsopathy.
Our results are consistent with those of COSTE et al.  who discovered that sciatica affects workers engaged in active physical work and unskilled workers who endureback-breaking activities, prolonged postures and briskspinal movement, recurrent heavy lifting and exposure to vibration.
In our study, sciatica bi-radicular injury is prevalent (44.3%). In 29.6%, sciatica affects L5 nerve root against 11.1% for S1. The various studies conducted highlight diverging results, although no explanation was provided to justify either of the root injuries. MIJIYAWA et al.  reported L5 root nerve injury prevalence. As for VALLS et al., they noted S1 injury (41.9%) against L5 (37.1%) .
In our study, 53% and 31.3% of the patients reported severe and mild pain respectively. Pain is a subjective symptom and many factors, especially psychology, determine its assessment. CHEOUR et al. observed severe and mild pain in 57% respectively .
Triggering factors mainly include prolonged standing (19.1%), prolonged sitting (18.3%), and heavy lifting (17.4%). However, the prevalent aggravating factor was prolonged standing (24.3%). As a relieving factor, supine position was much more recorded (44.4%).
YOUNES et al. reported high proportions of pain triggering factors (85.5%)  , as well as VALLS et al. (73%) . It should be noted that all these factors are determined by the daily activities of patients whether physical, strenuous or not, the poor conditions of our roads and observance or non-observance of postural hygiene.
Symptoms associated with pain were characterized by high paresthesia (59.1%) followed by intermittent claudication (40.9%). All the etiologies of sciatica result in painrelated paresthesia. Claudication of the sciatic nerve is much more observed in lumbar spinal stenosis. ONIANKITAN et al. in Togo, reported higher proportions, 84% of claudication of the sciatic nerve and 70% of paresthesia associated with pain . On the other hand, BEJIA et al. reported relatively low proportions of paresthesia (37%) and intermittent claudication (30%) .
The patients were positive to Doorbell sign (42.6%), followed by spinal stiffness (36.5%). Higher proportions were found in the study carried out by BEJIA et al. (Doorbell sign (70.3%) and spinal stiffness (89.1%)  while VALLS et al. recorded relatively low proportions of 15.6% for the former and 79.3% for the latter .
Sensory and motor testing including other neurological maneuvers conducted on all patients revealed Lasègue sign in 54.8% of the cases and sensory disorder in 24.4%. Regarding Lasègue sign, VALLS et al. had similar results to ours (54%) . CHEOUR et al. reported 34% sensory disorders and 36.7% Lasèguesign .
We noted that 13% of patients felt pains at an angle below 30˚ and 31.3% when an angle is greater than 60˚. Over half of the patients (51.3%) had Lasègue sign between 30˚ and 60˚.
Assessment of Lasègue angle involves several factors depending on the examiner, the size of a herniated disc or peri-spinal ligamentous laxity. Indeed, a variety of reports are conducted on Lasèguesign positivity. BEJIA et al. noted that 16.2% of their patients recorded Lasègue angle below or equal to 60˚ .
Of all para-clinical examinations, plain radiography was the most performed by the patients, representing 54.8%. This standard X-ray examination is available and affordable to the vast majority of patients, whereas scan (18.3%) is less available and geographically and financially limited.
Spinal osteoarthritis was etiologically prevalent (47%), followed by discopathy (26.1%), lumbar spinal stenosis (13%), spinal compression (7.8%) and spondylitis (6.1%). Different proportions were recorded by SONHAYE et al. in Togo where they reported in their lumbar spine CT scan-based study conducted in 2014, 11% for arthritis, 34% forherniated disc and 23% for disc protrusion . This represents higher aggregate proportions than that of discopathy (herniated disc and protruding disc) in our case. This could be explained by the low number of patients who could afford lumbar CT scan in our study; this examination being more recommended for diagnosis of herniated disc.
Sciatica is an increasing prevalent condition which stands out as a major reason for neurological consultation. There is need for better understanding to enable preventive care and proper management so as to prevent complicated debilitating forms of sciatica.