Recent reports suggest meditation practice improves attentional performance and emotional regulation. The process of meditation apparently increases activation in the prefrontal cortex (PFC) and stimulates the reticular nucleus of the thalamus, implicating the production and delivery of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). GABAergic inhibitory interneurons have a central role in cortical inhibition (CI), modulating cortical excitability and neural plasticity. Changes in CI, after completion of a single meditation session, were investigated and compared to a non-meditating control activity. Transcranial magnetic stimulation (TMS), a non-invasive method of examining CI, was used to evaluate changes before and after a 60 min meditation session. Seventy right-handed healthy subjects (n = 35 meditators, n = 35 non-meditators) were assessed using TMS related measures of cortical silent period (CSP) and short intra cortical inhibition (SICI), with stimulation of the motor cortex coordinated with EMG recording of peripheral hand muscles. For the meditators, CSP and SICI were measured before and after meditation sessions while age-sex matched healthy control subjects were identically assessed after a non-meditating activity (television watching). The meditators showed a statistically significant increase in CSP after meditation compared to non-meditators after an equivalent period of television watching (P = 0.02) while no significant between-group differences were observed in the SICI. These findings indicate meditation processes are linked to GABAergic cortical inhibition, a mechanism previously implicated in improved cognitive performance and enhanced emotional regulation.

Brain Stimul. 2012 Sep 7. pii: S1935-861X(12)00153-2. doi: 10.1016/j.brs.2012.08.005. Guglietti CL, Daskalakis ZJ, Radhu N, Fitzgerald PB, Ritvo P. York University, Department of Kinesiology and Health Science, Toronto, Ontario, Canada.

To describe two patients with lumbar facet synovial cysts causing sciatica and progressive neurological deficit. A 52-year-old female with bilateral sciatica and a neurological deficit that progressed to a foot drop; and a 54-year-old female with worsening sciatica and progressive calf weakness were seen at a major tertiary care centre. Diagnostic imaging studies revealed the presence of spinal nerve root impingement by large facet synovial cysts. Activity modification, gabapentinoid and non-steroidal anti-inflammatory medications were unsuccessful in ameliorating either patient's symptoms. One patient had been receiving ongoing lumbar chiropractic spinal manipulative therapy despite the onset of a progressive neurological deficit. Both patients eventually required surgery to remove the cyst and decompress the affected spinal nerve roots. Patients with acute sciatica who develop a progressive neurological deficit while under care, require prompt referral for axial imaging and surgical consultation. Primary care spine clinicians need to be aware of lumbar facet synovial cysts as a possible cause of acute sciatica and the associated increased risk of the patient developing a progressive neurological deficit.

J Can Chiropr Assoc. 2012 Sep;56(3):173-8. Arthur B, Lewkonia P, Quon JA, Street J, Bishop PB. Combined Neurosurgical and Orthopaedic Spine Program, Vancouver General Hospital, Division of Spine, Department of Orthopaedics & I.C.O.R.D. (International Collaboration on Repair Discoveries), University of British Columbia, Vancouver, Canada.