Pregnant women are at a risk of developing carpal tunnel syndrome (CTS) due to the 30% increase in the volume of blood. [1] It is the most common mononeuropathy of the median nerve which is at risk of compression due to its compact location in the carpal tunnel at the level of wrist joint due to the hypervolemic state of pregnancy . The compression and traction of the median nerve inside the carpal tunnel causes a neuropathy which is known as the carpal tunnel syndrome (CTS)[2] [Alfonso C et al]. Carpal tunnel syndrome consists of predominantly tingling and numbness in the typical median nerve distribution in the radial three and a half digits (thumb, index, long and radial side of the ring)[3] [Campbell WC et al]. The compression leads to decreased conduction velocity and increased nerve latency of the median nerve which is detected by the electrodiagnostic technique . Raised body mass index (BMI) is further contributing to the compression leading to a higher prevelance when compared to females of normal body mass index. BMI is calculated for all the pregnant females by taking into record the weight at the initiation of pregnancy.

RESEARCH METHODS OR METHODOLOGY

In this cross-sectional study 75 pregnant females (25 from each trimester) were recruited from the ANC OPD of J.N Medical College , Aligarh Muslim University , Aligarh. These served as cases . The controls were recruited from the gynaecology OPD of the same institute. the controls were age matched , healthy and non-pregnant females (25 in number ). (Table No 1) . The entire study population was screened for pregnancy related carpal tunnel syndrome via  the electrodiagnostic tecnique of nerve conduction study , which was done in the Neurophysiology Laboratory of the Physiology department , J.N Medical College , Aligarh Muslim University , Aligarh . Distal Motor Latency and nerve conduction velocity of the median nerve was taken into record . Diagnosis of PRCTS was made using the criteria of  cut off value of distal motor latency of median nerve being more than or equal to 4.2ms . (4) BMI was calculated for all the females recruited in the study ( for pregnant females ,using the weight at the initiation of pregnancy). Among the recruited study population 23% were belonging to the normal BMI range , 68% belonged to the  overweight and 9% belonged to the obese BMI range . (Table No. 2) The Categorization of BMI is according to the Indian population standards. Normal BMI = 18.5 to 22.9kg /m2, overweight=23 to 27.5 kg/m2, obese= >27.5kg/m2 [5].  the distribution of the right median motor nerve latency among the study population with different categories of BMI was taken into record . (table no 3).  The right median motor latency was found to be  ≥4.2ms in  13 overweight pregnant females and 15 obese pregnant female. 

Statistical analysis was done using pearson’s correlation coefficient and chi-sqaure test, distribution of median nerve latency (ms) among the overweight pregnant females.Out of the 59 overweight pregnant  females studied 13 females had their right median motor latency ≥4.2ms and 14  had their left median motor latency  ≥4.2ms. distribution of median nerve latency (ms) among the obese pregnant females. Out of the 18 obese pregnant females studied 15 females had their right  medianmotor latency ≥4.2ms and 12  had their left median motor latency  ≥4.2ms.

Among the diagnosed PRCTS cases 23% were overweight pregnant females and 77% were obese pregnant females. A higher BMI was seen significantly associated with the incidence of PRCTS in the  study population.(significance =0.000 by Chi-square tests depicts the distribution of the right median motor nerve latency among the study population with different categories of BMI. shows that right median motor latency was found to be  ≥4.2ms in  13 overweight pregnant females and 15 obese pregnant female.

Table No.1: Distribution of study population into cases and controls.

Table No. 2: Association between BMI and Median nerve motor Latency BMI  status of the diagnosed cases of the PRCTS.

Table No. 3: BMI distribution of the study population

Table No. 4 : BMI distribution of the study population

ASSOCIATION BETWEEN BMI AND  MOTOR LATENCY

Association between BMI Category and right median motor latency

Table No. 5 : Pearsons chi-square value value depicting association between BMI Category and right median motor latency

Pearsons chi-square value= 42.373 Df=2 Asymptotic. Significance= 0.000 (<0.05). It depicts significant association between higher BMI and right median motor  nerve conduction latency.

Association between BMI Category and left median motor latency

Table No. 6 : Pearsons chi-square value depicting association between BMI Category and left median motor latency

Pearsons chi-square value= 21.798 Df=2 Asymptotic. Significance= 0.000 (<0.05). It depicts significant association between higher BMI and left median motor  nerve conduction latency.

Correlation between  motor nerve conduction velocity and increased BMI.

Table no 7- Correlation between the medium motor nerve conduction velocity and Increased BMI.

Right median motor NCV Pearsons R= -0.344. It signifies moderately negative correlation between right median motor NCV and increasing BMI

Left median motor NCV Pearsons R= -0.352. It signifies moderately negative correlation between left median motor NCV and increasing BMI.

RESULT

Among the diagnosed cases of pregnancy related carpal tunnel syndrome 23% were over weight and 77% were obese pregnant females. Increased body mass index was found to have a positive correlation with the Distal Motor Latency of the Median nerve (p-value < 0.05) and a negetive corellation with the nerve conduction velocity of the Median nerve (pearson’s corellation coefficient = -0.35) in case of the recruited pregnant female population , which strengthens the fact that increased BMI has a  positive corellation with pregnancy related carpal tunnel syndrome . It is an important preventable risk factor which can significantly impact the disease outcome and the quality of life of the pregnant females with PRCTS.

DISCUSSION

Association between BMI and Median motor nerve latency was established by using the Chi-square test . Association between BMI category and median motor nerve (right band left ) latency was calculated. Significant association between a higher BMI and median motor nerve (right and left ) latency was found (significance = 0.000). BMI of the diagnosed cases of PRCTS was also assessed . Among the 36 cases Diagnosed of PRCTS cases  , 23% were overweight pregnant females and 77% were obese pregnant females. A higher BMI was seen significantly associated with the incidence of PRCTS in the study population. (significance = 0.000) by Chi-square tests in results. A similar finding was seen when F Turgut et al (2001) studied the prevelance of carpal tunnel syndrome (CTS) symptoms after delivery and its relationship to individual factors like BMI , age of the pregnant female , infant birth weight , parity and diabetes mellitus status during pregnancy. The study revealed that women with a higher BMI were at a greater risk of developing PRCTS. [6]. Similarly Charmaine Wright et al (2014) also analysed the prevelance , onset and risk factors of CTS during pregnancy. Their study suggested that mothers with CTS  had a higher rate of overweight, obesity and excessive gestational weight gain . [7]All of these were associated with increased risk of CTS.  

CONCLUSION

Among the 36 diagnosed cases of PRCTS , 23% were overweight pregnant females and 77% were obese pregnant females . A higher BMI was seen significantly associated with the incidence of PRCTS in the study population. The study found a very strong association (statistically significant ) of advancement of BMI with PRCTS.

Identifying the risk factors for PRCTS will help the pregnant females and their treating obstetricians for the prevention , early diagnosis and timely intervention of the occurance of this syndrome.

REFERENCES

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