Activation of Rectus Capitis Posterior Major Muscles During Voluntary Retraction of the Head in Asymptomatic Subjects

Assessment of axial rotation movement in cervical dystonia using cone-beam computed tomography

BACKGROUND

Cervical dystonia is a neurological disorder characterized by involuntary muscle contractions and abnormal postures of the head and neck. Botulinum neurotoxin injection is the first-line treatment. Imaging determination of the cervical segments involved (lower or upper according to the torticollis-torticaput [COL-CAP] Classification) is an aid in determining the muscles to be injected. We aimed to clarify the impact of dystonia on posture and rotational movement of cervical vertebrae in the transverse plane.

METHODS

A comparative study was conducted in a movement disorders department. Ten people with cervical dystonia and 10 matched healthy subjects (without cervical dystonia) were recruited. 3-D images of posture and cervical range of motion in axial rotation in the sitting position were recorded by using a cone-beam CT scanner. Range of rotational motion of the upper cervical spine from the occipital bone to fourth cervical vertebra was measured and compared between the two groups.

FINDINGS

The head posture analysis showed that the total cervical spine position was more significantly distant from the neutral position for people with dystonia than healthy subjects (p = 0.007). The rotational range of motion of the cervical spine was significantly lower in cervical dystonia participants than in healthy subjects for the total (p = 0.026) and for upper cervical spine (p = 0.004).

INTERPRETATION

We demonstrated, by means of cone-beam CT, that the disorganization of movements due to cervical dystonia affected the upper cervical spine and mostly the atlantoaxial joint. The involvement of rotator muscles at this cervical level should be considered more in treatments.

Suboccipital Muscles, Forward Head Posture, and Cervicogenic Dizziness

Dizziness or vertigo can be caused by dysfunction of the vestibular or non-vestibular systems. The diagnosis, treatment, and mechanism of dizziness or vertigo caused by vestibular dysfunction have been described in detail. However, dizziness by the non-vestibular system, especially cervicogenic dizziness, is not well known. This paper explained the cervicogenic dizziness caused by abnormal sensory input with references to several studies. Among head and neck muscles, suboccipital muscles act as stabilizers and controllers of the head. Structural and functional changes of the suboccipital muscles can induce dizziness. Especially, myodural bridges and activation of trigger point stimulated by abnormal head posture may be associated with cervicogenic dizziness.

Implied Evidence of the Functional Role of the Rectus Capitis Posterior Muscles

Context

Osteopathic physicians often target the rectus capitis posterior minor (RCPm) and rectus capitis posterior major (RCPM) muscles when using muscle energy or soft tissue cervical techniques to treat patients with head and neck pain. The RCPm and RCPM muscles are located deep within the posterior occipitoatlantal and atlantoaxial interspaces, respectively.

Objective

To characterize the functional role of RCPm and RCPM muscles by comparing electromyographic (EMG) activation patterns of these muscles with EMG activation patterns of specific flexor and extensor muscles of the head and neck, the sternocleidomastoid (SCM), and the splenius capitis (SC) muscles, respectively.

Methods

Asymptomatic participants were recruited from the Michigan State University College of Osteopathic Medicine student body. Disposable 25-gauge, bipolar fine-wire intramuscular electrodes were used to collect EMG data from the right and left RCPm and RCPM muscles. Surface electrodes were used to collect EMG data from the right and left SCM and SC muscles. Data were collected as participants performed 4 cycles of flexion and extension with an external 4-lb force applied to the back of the head and the forehead.

Results

In RCPM muscles, EMG activity was significantly greater (P<.003) during flexion and extension of the head and neck when an external force was applied to the back of the head. EMG activity in SCM muscles was significantly greater (P<.0001) during flexion and extension of the head and neck when an external force was applied to the forehead. The authors observed that EMG activity in SC muscles was significantly greater (P<.015) during flexion and extension of the head and neck when an external force was applied to the back of the head. No significant difference was found in EMG activity in RCPm muscles (P<.834) during flexion and extension of the head and neck, regardless of whether the external force was applied to the back of the head or the forehead.

Conclusion

The EMG activation patterns of the RCPm muscles suggest that their functional role may be to stabilize the occipitoatlantal joint by helping maintain congruency of the joint surfaces. In contrast, the EMG activation patterns of the RCPM muscles suggest that their functional role may be to contribute to extension of the head, primarily at the occipitoatlantal and the atlantoaxial joints.

Is There Support for the Paradigm 'Spinal Posture as a Trigger for Episodic Headache'? A Comprehensive Review

PURPOSE OF REVIEW

The International Classification of Headache Disorders provides an extensive framework to classify headaches. Physiotherapy is indicated if neuromusculoskeletal dysfunctions are involved in the pathophysiology. Maladaptive postures seem a dominant trigger in tension-type and cervicogenic headache. Yet, outcomes following physiotherapy vary. The absence of protocol studies to identify determinants concerning the role of spinal posture in headache might explain such variability. Hence, multi-dimensional profiling of patients with headache based on interactions between spinal posture, psychosocial and lifestyle factors might be essential. Therefore, the aim of this paper was to perform a comprehensive review to find support for the paradigm of spinal posture triggering episodic headache based on a multi-dimensional view on tension-type and cervicogenic headache including modern pain neuroscience.

RECENT FINDINGS

A review was conducted to support spinal posture-induced episodic headache. Pubmed, Web of Science, Pedro and the Cochrane database were explored based on the following 'Mesh' or 'Topics': 'Headache', 'Posture', 'Spine', 'Psychosocial', 'Lifestyle'. The contemporary review of neuroanatomical, biomechanical and non-nociceptive pathways, with integration of modern pain neuroscience in tension-type and cervicogenic headache, supports spinal posture as a trigger for episodic headache. Maladaptive postures can activate C1-C3 nociceptors. Convergence with trigeminal afferents at the trigeminocervical nucleus could explain spinal headache. Interactions with psychosocial and lifestyle factors might contribute to peripheral and central sensitisation. Neuroanatomical, biomechanical and non-nociceptive pathways seem to justify profiling patients based on a postural trigger. Further research is needed to determine the contribution of postural dysfunctions in headache and the effect of specific interventions.

Short-term effects of the suboccipital muscle inhibition technique and cranio-cervical flexion exercise on hamstring flexibility, cranio-vertebral angle, and range of motion of the cervical spine in subjects with neck pain: A randomized controlled trial

BACKGROUND

Cervical spinal instability often leads to neck pain and forward head posture (FHP). To improve neck pain and FHP, both the suboccipital muscle inhibition (SMI) technique and cranio-cervical flexion exercise (CCFE) have been used. However, little is known regarding the validity of hamstring flexibility in neck pain subjects after CCFE as a treatment index, and comparison between the SMI technique and CCFE for neck pain treatment.

OBJECTIVE

This study aimed to determine the short-term effects of SMI technique and CCFE, which represent passive and active exercise programs, respectively, and whether these improve the straight leg raise (SLR) test results, popliteal angle (PA), cranio-vertebral angle (CVA), and cervical range of motion (CROM) and are equally effective in immediate enhancement of such measures in neck pain subjects.

METHODS

Twenty subjects with neck pain were randomly allocated to the SMI and CCFE groups (n= 10 each). The outcomes were evaluated via clinical evaluation and SLR, PA, CVA, and CROM measurement before and after intervention.

RESULTS

SLR test results, PA, CVA (sitting and standing), and CROM (flexion, extension, lateral flexion, and right and left rotations) after both interventions were significantly higher than those before the interventions (P< 0.05). The SLR test results (left), PA, and CVA (standing) after the SMI technique improved to levels similar to those observed after CCFE.

CONCLUSIONS

Both the SMI technique and CCFE improve SLR test results, PA, CVA, and CROM and are equally effective in immediate enhancement of the hamstring flexibility, CVA, and CROM in subjects with neck pain.

Forward Head Posture and Activation of Rectus Capitis Posterior Muscles

Context: Rectus capitis posterior (RCP) muscles have physical attachments to the pain-sensitive spinal dura. Atrophy of these muscles is associated with chronic headache in some patients. The authors suspect that the significance of atrophy in the RCP muscles has been undervalued because the functional role of these muscles is not well defined.

Objective: To determine whether a statistically significant change in normalized levels of electromyographic activity in RCP muscles occurs when the head is voluntarily moved from a self-selected neutral head position to a protruded head position.

Methods: Fine wire, intramuscular electrodes were used to collect electromyographic data as asymptomatic participants moved their head from a neutral head position into a forward head position and back into the neutral head position. This sequence was repeated 4 times. Normalized levels of electromyographic activity were quantified using a 2-head position × 2 sides of the body repeated measures design that incorporated mixed-effects β regression models.

Results: Twenty participants were studied. Electromyographic activity collected from RCP muscles was found to increase as the head was voluntarily moved from a self-selected neutral head position (11% of maximum voluntary isometric contraction [MVIC] in RCP minor, 14% of MVIC in RCP major) into a protruded head position (35% of MVIC in RCP minor, 39% of MVIC in RCP major) (P<.001).

Conclusion: Rectus capitis posterior muscles may contribute to segmental stabilization of the occipitoatlantal and atlantoaxial joints by helping to maintain joint congruency during movement of the head.

A new device for measuring isometric force of the craniocervical flexor and extensor muscles and its reliability

OBJECTIVE

Craniocervical (CC) muscles control posture of the CC area. Muscle imbalance at this area induces musculoskeletal disorders. The purpose of this study was to develop a device for measuring isometric force of CC flexor and extensor muscles and to evaluate its intra-rater reliability.

METHOD

Isometric force of CC flexor and extensor muscles was measured in 20 women by one examiner on two days with a custom-made device. The intra-class correlation coefficient (ICC), standard error of measurements (SEM), smallest detectable difference (SDD), and Pearson correlation coefficient were computed.

RESULTS

The results of this study revealed that this device had excellent reliability (ICC: 0.98, SEM: 2.29 N, SDD: 6.36 N, Pearson correlation coefficient: 0.97 for CC flexor muscles and ICC: 0.97, SEM: 2.13 N, SDD: 5.91 N, Pearson correlation coefficient: 0.94 for CC extensor muscles).

DISCUSSION

This new device can improve knowledge about the CC muscle and efficacy of treatments in patients with poor posture.