Cerebellar Tonsillar Descent Mimicking Chiari Malformation.

Chiari I malformation has been defined as cerebellar tonsillar descent greater than 5 mm below the foramen magnum. Suboccipital decompression remains the mainstay of treatment for symptomatic patients. Other conditions sometimes have imaging features that mimic Chiari I malformation. These patients are at risk of misdiagnosis and mismanagement, including surgery that may be unnecessary or may even worsen the underlying condition. The aim of this study was to analyse a series of Chiari I malformation mimics and identify differentiating imaging features. The mimics are categorised as post-traumatic cranio-cervical junction arachnoiditis, dural band, spontaneous intracranial hypotension, idiopathic intracranial hypertension, and cysts. Better understanding of these conditions will assist with diagnosis and optimal management, including avoiding unnecessary surgery.

Recruitment of discrete regions of the psoas major and quadratus lumborum muscles is changed in specific sitting postures in individuals with recurrent low back pain.

STUDY DESIGN: Cross-sectional controlled laboratory study. OBJECTIVES: To investigate potential changes in the function of discrete regions of the psoas major (PM) and quadratus lumborum (QL) with changes in spinal curvatures and hip positions in sitting, in people with recurrent low back pain (LBP). BACKGROUND: Although the PM and QL contribute to control of spinal curvature in sitting, whether activity of these muscles is changed in individuals with LBP is unknown. METHODS: Ten volunteers with recurrent LBP (pain free at the time of testing) and 9 pain-free individuals in a comparison group participated. Participants with LBP were grouped into those with high and low erector spinae (ES) electromyographic (EMG) signal amplitude, recorded when sitting with a lumbar lordosis. Data were recorded as participants assumed 3 sitting postures. Fine-wire electrodes were inserted with ultrasound guidance into fascicles of the PM arising from the transverse process and vertebral body, and the anterior and posterior layers of the QL. RESULTS: When data from those with recurrent LBP were analyzed as 1 group, PM and QL EMG signal amplitudes did not differ between groups in any of the sitting postures. However, when subgrouped, those with low ES EMG had greater EMG signal amplitude of the PM vertebral body and QL posterior layer in flat posture and greater EMG signal amplitude of the QL posterior layer in short lordotic posture, compared to those in the pain-free group. For the group with high ES EMG, the PM transverse process and PM vertebral body EMG was less than that of the other LBP group in short lordotic posture. CONCLUSION: The findings suggest a redistribution of activity between muscles that have a potential extensor moment in individuals with LBP. The modification of EMG of discrete fascicles of the PM and QL was related to changes in ES EMG signal amplitude recorded in sitting.

Changes in direction-specific activity of psoas major and quadratus lumborum in people with recurring back pain differ between muscle regions and patient groups.

Psoas major (PM) and quadratus lumborum (QL) muscles have anatomically discrete regions. Redistribution of activity between these regions has been observed in people with low back pain (LBP). We hypothesised that the bias of activity of specific regions of PM and QL towards trunk extension may change depending on whether LBP individuals have more or less erector spinae (ES) activity in an extended/upright lumbar posture. Ten volunteers with recurring episodes of LBP and nine pain-free controls performed isometric trunk efforts in upright sitting. LBP individuals were subgrouped into those with high and low ES electromyographic activity (EMG) when sitting with a lumbar lordosis. Fine-wire electrodes were inserted into fascicles of PM arising from the transverse process (PM-t) and vertebral body (PM-v) and anterior (QL-a) and posterior layers (QL-p) of QL. The LBP group with low ES EMG had greater bias of PM-t, PM-v and QL-p towards trunk extension. The LBP group with high ES activity showed less PM activity towards extension. These findings suggest redistribution of activity within and/or between these muscles with extensor moments. This is likely to be important to consider for effective clinical interventions for individuals with LBP.

Changes in regional activity of the psoas major and quadratus lumborum with voluntary trunk and hip tasks and different spinal curvatures in sitting.

STUDY DESIGN: Cross-sectional controlled laboratory study. OBJECTIVES: To investigate the function of discrete regions of psoas major (PM) and quadratus lumborum (QL) with changes in spinal curvature and hip position. BACKGROUND: Anatomically discrete regions of PM and QL may have differential function on the lumbar spine, based on anatomical and biomechanical differences in their moment arms between fascicles within each muscle. METHODS: Fine-wire electrodes were inserted with ultrasound guidance into PM fascicles arising from the transverse process (PM-t) and vertebral body (PM-v) and anterior (QL-a) and posterior (QL-p) layers of QL. Recordings were made on 9 healthy participants, who performed 7 tasks with maximal voluntary efforts and adopted 3 sitting postures that involved different spinal curvatures and hip angles. RESULTS: Activity of PM-t was greater during trunk extension than flexion, whereas activity of PM-v was greater during hip flexion than trunk efforts. Activity of QL-p was greater during trunk extension and lateral flexion, whereas QL-a showed greater activity during lateral flexion. During sitting tasks, PM-t was more active when sitting with a short lordosis than a flat (less extended) lumbar spine posture, whereas PM-v was similarly active in both sitting postures. CONCLUSION: Activity of PM-t was more affected by changes in position of the lumbar spine than the hip, whereas PM-v was more actively involved in the movement of the hip rather than that of the lumbar spine. Moreover, from its anatomy, PM-t has a combined potential to extend/lordose the lumbar spine and flex the hip, at least in a flexed-hip position.

Differential activity of regions of the psoas major and quadratus lumborum during submaximal isometric trunk efforts.

Controversy exists regarding the function of psoas major (PM) and quadratus lumborum (QL) at the lumbar spine. The functions of discrete regions of PM and QL were studied during trunk loading tasks. Twelve healthy participants performed isometric trunk loading tasks in various directions in upright sitting. Fine-wire electromyography (EMG) electrodes were inserted under ultrasound guidance into PM fascicles arising from the transverse process (PM-t) and vertebral body (PM-v) and the anterior (QL-a) and posterior (QL-p) layers of QL on the right side. Although right PM-t and PM-v were both active during right lateral-flexion trunk efforts, their activity was opposite in the sagittal plane, with greater PM-t towards extension and PM-v towards flexion. QL-a and QL-p were similarly active, though QL-p was active to a greater percentage of MVC during right trunk lateral-flexion efforts. Activity of QL-p was modulated with respiratory phase during the loading tasks with trunk efforts towards the right lateral-flexion/flexion and right lateral-flexion directions. These findings provide novel understanding of the unique activation of discrete regions of PM and QL. These differences must be considered in future EMG studies to better understand the function of these deeply situated trunk muscles in the control of the lumbar spine.