Spinal manipulation and decreasing blood pressure
The results of systematic review and meta-analysis on effect of spinal mobilization and manipulation on cardiovascular responses concluded that;
"Spinal manipulations and mobilizations showed significant reduction in SBP.....On sensitivity analysis, there was a significant decrease in both systolic as well as diastolic blood pressure and heterogeneity was also very low. Results were insignificant for heart rate. Therefore, within the limitations of the present systematic review and meta-analysis, it can be concluded that spinal manipulations and mobilizations may result in decrease of systolic as well as diastolic blood pressure.
For more details the full reference is listed below.
Manual therapy techniques, like spinal mobilizations, high-velocity, low-amplitude manipulations and mobilization with movement are frequently used by physiotherapists along with various therapeutic exercises to treat or manage spinal pain and movement dysfunction.1,2,3 Spinal mobilizations are referred as “graded passive, oscillatory movements applied to the spine that moves it to the end of its available range”.3 These mobilizations are performed within the normal range of motion in such a way that it may be controlled by the patient, whereas manipulations are rapid movement at the end of the range of movement that cannot be controlled by the patient.4 Although both the techniques are different in application, still the main emphasis of both techniques is continuous assessment and evaluation.1 According to the findings of assessment and evaluation, spinal manipulative therapies are applied at varying speed and amplitude.3
Spinal manipulative therapies are mainly indicated to alleviate spinal pain and correct spinal malalignment.1 Spinal pain is a very common disorder affecting a significant number of populations resulting in substantial disability and economic burden. It is estimated that approximately 54–80% population suffer from spinal pain at any stage of their life.5 Research evidence suggests that workplace physical and psychosocial factors also contribute to the development of spinal pain. Gender, occupation, emotional problems, smoking, poor job satisfaction, awkward posture and poor work environment may also be associated with spinal pain.6
Spinal malalignments (such as scoliosis) are mainly caused by body’s abnormal posture, asymmetries in bone growth and abnormalities of neuromuscular system. Asymmetrical load applied to vertebral axis is the main cause of development and progression of spinal deformity. Altered biomechanics, weakness of abdominal muscles, joint laxity and increased extensibility of soft tissues can be risk factors for the progression of spinal malalignments.7 As a response, body progressively attains compensatory mechanism from other flexible parts of spine to preserve the spine posture. This puts additional stress over the musculoskeletal system and further leads to pain.8 Literature suggests that psychosomatic symptoms such as stress, anxiety and depression are strongly associated with spinal pain and malalignment.9 Spinal pain, mainly in cervical region, is strongly associated with migraine and severe headache with prevalence rate of 15.1%. Other associated symptoms are spine stiffness, headache, numbness, dizziness, sleeping difficulties, fatigue and memory as well as cognitive deficits.6
Evidence shows that spinal malalignment of cervical spine (especially C1 vertebra) can potentially injure, impair and compress brainstem neural pathways which is the regulatory centre of cardiovascular functions. Changes in the anatomical position of atlas [C1] and connected chain result in circulatory changes of vertebral artery. These circulatory abnormalities around the atlas vertebra and posterior fossa of brain have significant correlation with worsening of hypertension.11 Involvement of thoracic spine alone or in combination with lumbar spine results in cardiovascular and respiratory complications.10
Therefore, it may be suggested that the spinal manipulations, especially of cervical region can affect heart rate and blood pressure. The primary mechanism of these benefits can be parasympathetic stimulation.3 SMT of cervical spine may directly stimulate the parasympathetic flow via brain stem or indirectly through the stimulation of carotid sinus which further stimulates the brain stem via nucleus tractus solitaries (NTS).11,12
The existing research literature regarding effect of spinal manipulation and mobilization on cardiovascular parameters is still ambiguous. Studies corroborate11,13,14,15,16,17,18,21,22,23,26,27,28 as well as contradict12,19,20,24,25 the effects of manual therapy on cardiovascular parameters. These studies also have various methodological flaws. Further, small sample size of these studies limits the generalizability of their results.