Changes in gray matter volume after microsurgical lumbar discectomy: a longitudinal analysis

Abstract

People around the world suffer chronic lower back pain. Because spine imaging often does not explain the degree of perceived pain reported by patients, the role of the processing of nociceptor signals in the brain as the basis of pain perception is gaining increased attention. Modern neuroimaging techniques (including functional and morphometric methods) have produced results that suggest which brain areas may play a crucial role in the perception of acute and chronic pain. In this study, we examined 12 patients with chronic low back pain and sciatica, both resulting from lumbar disc herniation. Structural magnetic resonance imaging (MRI) of the brain was performed 1 day prior to and about 4 weeks after microsurgical lumbar discectomy. The subsequent MRI revealed an increase in gray matter volume in the basal ganglia but a decrease in volume in the hippocampus, which suggests the complexity of the network that involves movement, pain processing, and aspects of memory. Interestingly, volume changes in the hippocampus were significantly correlated to preoperative pain intensity but not to the duration of chronic pain. Mapping structural changes of the brain that result from lumbar disc herniation has the potential to enhance our understanding of the neuropathology of chronic low back pain and sciatica and therefore may help to optimize the decisions we make about conservative and surgical treatments in the future. The possibility of illuminating more of the details of central pain processing in lumbar disc herniation, as well as the accompanying personal and economic impact of pain relief worldwide, calls for future large-scale clinical studies.

Are age-related deficits in route learning related to control of visual attention?

“…A possible explanation for the differences in results between our study and the study by Dowiasch et al ( 2015 ) comes from the fact that participants in their study were actively locomoting through the environment, while our participants were passively transported along the route. It is conceivable that age-related differences in postural control (Jimenez et al, 2016 ), control of locomotion and steering cause differences in gaze behaviour.…”

“…First, we focused on general gaze patterns during the learning phase. For the vast majority of measures, there were no differences between age groups, which was surprising, given evidence from Dowiasch et al ( 2015 ), who reported age differences in general gaze parameters. The bootstrapped t test analysis demonstrated that our observed comparisons fall well within the distribution of t values when comparing groups without differences, suggesting our results represent no difference between age groups as opposed to a type 2 error.…”

“…Given the lack of previous research linking gaze behaviour, ageing and route learning, we took an exploratory approach to analysing eye-tracking measures during route learning. As in Dowiasch et al ( 2015 ), we compared saccade amplitude, peak velocity, average velocity and frequency (number of saccades per second) between age groups for eye-tracking data from the learning phase using analysis of variance (ANOVA). We did the same for the Direction Test with the addition of average fixation duration.…”

“…Systematic differences in gaze behaviour between younger and older adults have been reported in non-route learning tasks. Dowiasch, Marx, Einhäuser and Bremmer ( 2015 ) measured several gaze parameters, whilst older and younger participants walked through an environment. While participants did not solve a specific navigation task, older adults showed reduced saccade frequency, amplitude, peak and average velocity.…”

A longitudinal study of pain, personality, and brain plasticity following peripheral nerve injury

“…For instance, after 3 to 4 weeks of pain rehabilitative treatment in pediatric complex regional pain syndrome, cortical thickness increased in regions implicated in pain modulation along with lower pain intensity. 26 In chronic low back pain, gray matter changed after microsurgical lumbar discectomy 46 in the basal ganglia and hippocampus; regions involved in motor, emotional, cognitive, and learning. 3,55 Reversal of cortical thinning abnormalities in the insula was reported posttreatment in low back pain patients that correlated with reduced pain.…”