Distinct brainstem to spinal cord noradrenergic pathways differentially regulate spinal neuronal activity

Brainstem to spinal cord pathways modulate spinal neuronal activity. We implemented locus coeruleus (LC) targeting strategies by microinjecting CAV-PRS-ChR2 virus in the spinal cord (LC:SC module) or LC (LC:LC module). While activation of both modules inhibited evoked spinal neuronal firing via α1-adrenoceptor-mediated actions, LC:SC opto-activation abolished diffuse noxious inhibitory controls. The LC as a pain generator is likely mechanistically underpinned by maladaptive communication with discrete descending modulatory pathways.

Complications and their management

This chapter reviews the complications that can occur after minimally invasive surgical fusion of the sacroiliac joint, focusing on infection and neurovascular injuries and their prevention and treatment. The sacroiliac joint has been identified as a potential pain generator in 15% to 30% of chronic low back pain and post-laminectomy syndrome patients. Minimally invasive sacroiliac joint fusion via the lateral approach is effective and better tolerated than the open surgical approach. Most of the current studies have focused on efficacy and patient satisfaction as opposed to the safety profile of the procedure. There is a dearth of literature regarding the safety of minimally invasive sacroiliac joint fusion. Over the past few years, a novel posterior approach to sacroiliac joint fusion has become more common that theoretically is safer and potentially as efficacious as the lateral approach.

The Sacroiliac Joint as a Cause of Pain – Review of the Sacroiliac Joint Morphology and Models for Pain Genesis

Introduction In recent years, the sacroiliac joint has become increasingly important as a generator of low back pain with and without pseudo-radicular pain in the legs. Up to 27% of reported back pain is generated by disorders in the sacroiliac joint. Method This review is based on a selective literature search of the sacroiliac joint (SIJ) as a possible pain generator. It also considers the anatomical structures and innervation of the sacroiliac joint. Results The SIJ is a complex joint in the region of the posterior pelvis and is formed by the sacrum and the ilium bones. The SIJ is very limited in movement in all three planes. Joint stability is ensured by the shape and especially by strong interosseous and extraosseous ligaments. Different anatomical variants of the sacroiliac joint, such as additional extra-articular secondary joints or ossification centres, can be regularly observed in CT scans. There is still controversy in the literature regarding innervation. However, there is agreement on dorsal innervation of the sacroiliac joint from lateral branches of the dorsal rami of the spinal nerves S I–S III with proportions of L III and L IV as well S IV. Nerve fibres and mechanoreceptors can also be detected in the surrounding ligaments. Conclusion A closer look at the anatomy and innervation of the SIJ shows that the SIJ is more than a simple joint. The complex interaction of the SIJ with its surrounding structures opens the possibility that pain arises from this area. The SIJ and its surrounding structures should be included in the diagnosis and treatment of back and leg pain. Published literature include a number of plausible models for the sacroiliac joint as pain generator. The knowledge of the special anatomy, the complex innervation as well as the special and sometimes very individual functionality of this joint, enhance our understanding of associated pathologies and complaints.

Midarch Foot Pain: Entrapment Neuropathy of the Distal Medial Plantar Nerve and Its Branches

Medial forefoot pain, or midarch pain, is usually attributed to plantar fasciitis. The authors present their findings of a previously unreported nerve entrapment of the medial proper plantar digital nerve (MPPDN). Ten fresh-frozen cadaveric specimens were analyzed for anatomical variance in the nerve distribution of the MPPDN. In addition, clinical results from a retrospective review of nine patients who underwent surgical nerve decompression of the MPPDN are presented. Significant anatomical variance was found for the MPPDN in the cadaveric dissection of 10 fresh-frozen specimens. Nine patients with a clinical diagnosis of entrapment of the MPPDN all obtained excellent pain relief with surgical external neurolysis. Only one complication occurred: a hypertrophic scar formation that was successfully treated with intralesional steroid injections. The authors believe that this MPPDN entrapment is often overlooked or misdiagnosed as plantar fasciitis. Surgical peripheral nerve decompression of this nerve can provide positive outcomes for patients suffering from midarch foot pain caused by this pain generator.

Pelvis and Groin

The groin and pelvis represent a large anatomical region with disorders affecting a diverse array of osteoarticular, musculotendinous, gastrointestinal, and genitourinary structures. Although it can be difficult to pinpoint a pain generator clinically, patients often present with non-specific orthopedic complaints at the anterior, lateral, inferior, or posterior aspect of the pelvis. The purpose of this practical review is to highlight the most important anatomy, injury patterns, and diagnostic imaging findings at each of these four sites.

Post-traumatic cephalalgia

After traumatic brain injury (TBI), a host of symptoms of varying severity and associated functional impairment may occur. One of the most commonly encountered and challenging to treat are the post-traumatic cephalalgias. Post-traumatic cephalalgia (PTC) or headache is often conceptualized as a single entity as currently classified using the ICHD-3. Yet, the terminology applicable to the major primary, non-traumatic, headache disorders such as migraine, tension headache, and cervicogenic headache are often used to specify the specific type of headache the patients experiences seemingly disparate from the unitary definition of post-traumatic headache adopted by ICHD-3. More complex post-traumatic presentations attributable to brain injury as well as other headache conditions are important to consider as well as other causes such as medication overuse headache and medication induced headache. Treatment of any post-traumatic cephalalgia must be optimized by understanding that there may be more than one headache pain generator, that comorbid traumatic problems may contribute to the pain presentation and that pre-existing conditions could impact both symptom complaint, clinical presentation and recovery. Any treatment for PTC must harmonize with ongoing medical and psychosocial aspects of recovery.