Clinical Anatomical Research Of Suboccipital Musculatures And Relationship Between Musculatures And Chronic Headache

Background and Objective:The suboccipital region was described as a much complicated area.The suboccipital musculatures,located posterior to the atlas and the axis,included the rectus capitis posterior minor(RCPmi)muscle,the rectus capitis posterior major(RCPma)muscle,the obliquus capitis inferior(OCI)muscle and the obliquus capitis superior muscle.Recently,this region has attracted lots of attention from scientific research to clinical trials.Hack et al.observed and described the relationship between the deep suboccipital muscle and the spinal dura.They found a physical connective tissue bridge between the RCPmi and the dorsal spinal dura at the atlanto-occipital junction,named Myodural Bridge(MDB).Subsequently,many studies had verified the presence of this connective tissue in human body.The existence of the MDB derived from the RCPma,OCI and nuchal ligament(NL)were also described by following studies.The MDB was demonstrated inserting into the posterior atlanto-axial interspace and fusing with the posterior side of upper cervical spinal dura.A research observed an intrinsic fascial structure,as a part of the NL,was termed as the To Be Named Ligament(TBNL).We also found that the MDB-complex was existed in the atlanto-occipital and atlanto-axial interspace.In clinical practice,a new hypothesis of chronic headaches was proposed that the MDB plays an important role in chronic headaches.Whenever pathological changes occurred in the RCPmi,improper forces could be transmitted through the MDB to the pain-sensitive spinal dura and change the circulation of CSF,resulting in chronic pain.Despite the importance of RCPmi and MDB,however,whether existed a special suboccipital muscle morphology to change the force direction in the atlanto-occipital and atlanto-axial interspace,influenced the CSF through MDB,and thus lead to the occurrence of headache? Our study continued an extensive anatomical study and imaging research,to investigate the special morphological changes in suboccipital muscles,the differences of the RCPmi between normal adults and chronic headache patients,we also prepared a RCPmi headache rat model,aiming to assess the potential effects of the MDB and find a and new explanation of the chronic headache.Materials and methods:Thirty-five donated adult head-neck specimens(23 male,12 female)were used for anatomic study.The suboccipital muscles(RCPmi,RCPma and OCI)and the NL were all exposed We observed and counted the existence of the second terminations in all the thirty-five specimens and the types of the TBNL was also carried out in our study.The relationship between the second terminations of the suboccipital muscles and the types of the TBNL were examined for statistical significance.In imaging collection,the control group was composed of 120 participants who did not meet the diagnostic criteria of any headache and other physical illnesses.The group of 115 patients has suffered from chronic headaches for more than 15 days per month for longer than 3 months,excluding a history of cardiovascular,neurologic or other certain cervical disorders.The left RCPmi of all volunteers were scanned with 30° deviation from the sagittal plane by T2-weighted MRI scanning.After the collection,these selected images were measured using Mimics Software.The correlation between the morphological changes of RCPmi and chronic headaches were analyzed using the Statistical Package for the Social Sciences.In the establishment of headache model,80 male SD rats were used and randomly divided into saline control group(NS group),botulinum toxin A group(A group)and control group(EC group).In each rat,the bilateral RCPmi were injected with 5u L of normal saline and botulinum toxin A in NS group and A group respectively,for preparation RCPmi chronic headache of rat model.EC group were treated with botulinum toxin A injection in bilateral musculi biceps femoris of rats as control test.The behavior of rats(the scratching head,climbing cage and moving around)and vital signs(breathing,heart rate and blood pressure)were observed and measured before and after the model preparation in the period of 24 h,1w,2w 3w,4w,respectively.Results:1.The relationship between the second terminations and the types of the TBNLIn our study,the existence of the second terminations originated from these suboccipital muscles had been confirmed,and the incidence of second terminations was 34.29%(24 out of 70 sides).In these 24 sides,the second terminations originated from the RCPma were found in 20 sides,showed the greatest incidence rate which was nearly 28.57%;8 sides showed the second terminations originated from the RCPmi,the incidence rate was 11.43%;the OCI originated were found in 6 sides,the incidence rate was 8.57%,which was smallest.In some cases,the second terminations have co-existed from different suboccipital muscles and terminated at the TBNL.The coexistence of second terminations originated together from the RCPma and the OCI were observed in4sides;the second terminations originated from the RCPma and the RCPmi coexisted in6 sides.The radiate type of the TBNL was found in 50 out of 70 sides with the incidence of71.43 %.20 of 70 sides were found to be arcuate type of TBNL with 28.57%.In combined observation of the existence of the second terminations and the types of the TBNL,the second terminations were found existed in 19 out of 20 sides with the arcuate type of the TBNL.In 50 of 70 sides with the radiate type of the TBNL,only 5sides had the second termination,including 1 side from the RCPma,4 sides from the RCPma and OCI,simultaneously.No second termination existed in other 45 sides.The correlation of the second terminations of suboccipital muscles and the types of TBNL were considered statistically significant(P<0.001).2.The correlation between morphological changes of RCPmi and chronic headachesTwo groups were under comparative analysis in this research.The mean age of the control group was 42.50±15.20 years old,including 45 males and 75 females and the mean age of the headache group was 43.63±15.69 years old,including 45 males and 70 females.No statistic differences were combined in gender and age.The mean value of the RCPmi was 84.48±26.94 mm2 in the control group and was 110.95±44.08 mm2 in the headache group.The analysis of the data showed that the sectional area of the RCPmi was bigger in males than in females(P<0.001).Given that significant gender differences existed,it was advantageous to provide gender specific analysis for both groups.Based on the statistics,the headache group showed greater hypertrophy than the control group in both males(P<0.001)and females(P = 0.001).Of the 235 MR images analyzed,the data of the two groups—the control group and the headache group were considered statistically significant.It indicated that the headache patients had a significant hypertrophy of the RCPmi compared to the control group.3.Behavioral observation of chronic headache animalIn the behavioral observation,it was found that NS group and EC group behavioral indicators were stable in every period time(24h,1w,2w,3w and 4w)and there were not statistically significant(P>0.05).There were no significant differences in the period time of 24 h,1w and 2w in scratching head,climbing cage frequency and moving around before and after A group.In the 3w period of time,the moving around in model group was not statistically significant,while the scratching head and climbing cage frequency were statistically significant(P<0.05).In the 4w time period,the scratching head frequency was also statistically significant in A group(P<0.05).In the measurement of vital signs after through statistical analysis,the NS group and EC group of vital signs include breathing,blood pressure and heart rate in each time period were not statistically significant(P>0.05).There is no statistical significance,compared within the A group and between groups in 24 h,1w,2w and 4w of the breathing,blood pressure and heart rate.In the 3w period of time,breathing was not statistically significant within the model,while the blood pressure and heart rate were statistically significant before and after modeling(P<0.05).Conclusion:1.The existence of second terminations from the suboccipital muscles and there was relationship between the second termination and the arcuate TBN;2.Chronic headache patients suffered from more hypertrophy of the RCPmi than control group;3.Injection of botulinum toxin into the RCPmi can cause headache-like behavioral changes in rats.