Frank H. Willard

Sensory stimulation-guided sacroiliac joint radiofrequency neurotomy: technique based on neuroanatomy of the dorsal sacral plexus.

Study Design. A retrospective audit and examination of anatomic findings. Objective. To examine the effectiveness of sensory stimulation-guided radiofrequency neurotomy for the treatment of recalcitrant sacroiliac joint pain. Summary of Background Data. Sacroiliac joint-mediated pain is a distinct clinical entity. The prevalence of intra-articular pain arising from the sacroiliac joint in patients with low back pain has been estimated at 15% to 30%. Unfortunately, the clinical success of current treatment methods for chronic sacroiliac pain is discouraging. Based on the anatomy of the sacral posterior primary rami and their lateral branch nerves, an anatomically based sensory stimulation-guided radiofrequency technique was developed to overcome the inherent challenge posed by the variable topography of the sacral lateral branch nerves. Materials and Methods. &NA; Anatomic Study. Meticulous dissection exposing the dorsal sacral plexus and lateral branch nerves entering the sacroiliac joint complex was performed on three cadaveric specimens. Small-gauge wires were placed adjacent to the lateral branch nerves entering the joint and over the dorsal sacrum to the dorsal sacral foramina. Fluoroscopic images were obtained correlating the location and number of these branches arising from the posterior primary rami of S1–S3 to identifiable bony landmarks. Clinical Study. A retrospective chart review was performed selecting patients who underwent sensory stimulation-guided sacral lateral branch radiofrequency neurotomy after dual analgesic sacroiliac joint deep interosseous ligament analgesic testing between February 17, 1998 and March 15, 1999. Results. A total of 14 patients met inclusion criteria for this retrospective study. Success was defined as greater than 60% consistent subjective relief and greater than a 50% consistent decrease in visual integer pain score, maintained for at least 6 months after the procedure. Sixty-four percent of patients experienced a successful outcome, with 36% experiencing complete relief. Fourteen percent of patients did not achieve any improvement. No patients experienced a complication or worsening of their pain from the procedure. Conclusions. A sensory stimulation-guided approach toward the identification and subsequent radiofrequencythermocoagulation of symptomatic sacral lateral branch nerves appears to offer significant therapeutic advantages over existing therapies for the treatment of chronic sacroiliac joint complex pain

The thoracolumbar fascia: anatomy, function and clinical considerations

In this overview, new and existent material on the organization and composition of the thoracolumbar fascia (TLF) will be evaluated in respect to its anatomy, innervation biomechanics and clinical relevance. The integration of the passive connective tissues of the TLF and active muscular structures surrounding this structure are discussed, and the relevance of their mutual interactions in relation to low back and pelvic pain reviewed. The TLF is a girdling structure consisting of several aponeurotic and fascial layers that separates the paraspinal muscles from the muscles of the posterior abdominal wall. The superficial lamina of the posterior layer of the TLF (PLF) is dominated by the aponeuroses of the latissimus dorsi and the serratus posterior inferior. The deeper lamina of the PLF forms an encapsulating retinacular sheath around the paraspinal muscles. The middle layer of the TLF (MLF) appears to derive from an intermuscular septum that developmentally separates the epaxial from the hypaxial musculature. This septum forms during the fifth and sixth weeks of gestation. The paraspinal retinacular sheath (PRS) is in a key position to act as a ‘hydraulic amplifier’, assisting the paraspinal muscles in supporting the lumbosacral spine. This sheath forms a lumbar interfascial triangle (LIFT) with the MLF and PLF. Along the lateral border of the PRS, a raphe forms where the sheath meets the aponeurosis of the transversus abdominis. This lateral raphe is a thickened complex of dense connective tissue marked by the presence of the LIFT, and represents the junction of the hypaxial myofascial compartment (the abdominal muscles) with the paraspinal sheath of the epaxial muscles. The lateral raphe is in a position to distribute tension from the surrounding hypaxial and extremity muscles into the layers of the TLF. At the base of the lumbar spine all of the layers of the TLF fuse together into a thick composite that attaches firmly to the posterior superior iliac spine and the sacrotuberous ligament. This thoracolumbar composite (TLC) is in a position to assist in maintaining the integrity of the lower lumbar spine and the sacroiliac joint. The three‐dimensional structure of the TLF and its caudally positioned composite will be analyzed in light of recent studies concerning the cellular organization of fascia, as well as its innervation. Finally, the concept of a TLC will be used to reassess biomechanical models of lumbopelvic stability, static posture and movement.

The sacroiliac joint: an overview of its anatomy, function and potential clinical implications

This article focuses on the (functional) anatomy and biomechanics of the pelvic girdle and specifically the sacroiliac joints (SIJs). The SIJs are essential for effective load transfer between the spine and legs. The sacrum, pelvis and spine, and the connections to the arms, legs and head, are functionally interrelated through muscular, fascial and ligamentous interconnections. A historical overview is presented on pelvic and especially SIJ research, followed by a general functional anatomical overview of the pelvis. In specific sections, the development and maturation of the SIJ is discussed, and a description of the bony anatomy and sexual morphism of the pelvis and SIJ is debated. The literature on the SIJ ligaments and innervation is discussed, followed by a section on the pathology of the SIJ. Pelvic movement studies are investigated and biomechanical models for SIJ stability analyzed, including examples of insufficient versus excessive sacroiliac force closure.

The ability of single site, single depth sacral lateral branch blocks to anesthetize the sacroiliac joint complex

OBJECTIVE To determine the physiologic effectiveness of single site, single depth sacral lateral branch injections. DESIGN Randomized, controlled, and double-blinded study. SETTING Outpatient pain management center. PATIENTS Fifteen asymptomatic volunteers. INTERVENTIONS The dorsal sacroiliac ligament was probed and the sacroiliac joint was injected with contrast medium until capsular distension occurred. The presence or absence of pain with each maneuver was noted. Under double-blind conditions, subjects returned 1 week later for L5 dorsal ramus and S1-4 lateral branch injections; 10 subjects received 4% lidocaine (active) injections while five subjects received saline (control) injections. After 30 minutes, subjects had repeat ligamentous probing and capsular distension of the same sacroiliac joint that was previously tested. The presence or absence of pain with each maneuver was noted. In a parallel anatomic study, S1 and S2 lateral branch injections with green dye were performed on two nonembalmed cadavers. Dissection was undertaken to quantify the degree of staining of these target lateral branch nerves. OUTCOME MEASURES Presence or absence of pain for ligamentous probing and sacroiliac joint capsular distension. RESULTS Forty percent had no discomfort upon repeat ligamentous probing after active lateral branch injections while 100% retained pain upon repeat ligamentous probing with control lateral branch injections. Forty percent of the active group and 20% of the control group did not feel repeat capsular distension of the sacroiliac joint after the lateral branch injections. In the anatomic study, 11 lateral branch nerves were isolated while staining occurred in only four cases or 36%. CONCLUSIONS Anatomic limitations exist with single site, single depth sacral lateral branch injections rendering them physiologically ineffective on a consistent basis.

A description of the lumbar interfascial triangle and its relation with the lateral raphe: anatomical constituents of load transfer through the lateral margin of the thoracolumbar fascia

Movement and stability of the lumbosacral region is contingent on the balance of forces distributed through the myofascial planes associated with the thoracolumbar fascia (TLF). This structure is located at the common intersection of several extremity muscles (e.g. latissimus dorsi and gluteus maximus), as well as hypaxial (e.g. ventral trunk muscles) and epaxial (paraspinal) muscles. The mechanical properties of the fascial constituents establish the parameters guiding the dynamic interaction of muscle groups that stabilize the lumbosacral spine. Understanding the construction of this complex myofascial junction is fundamental to biomechanical analysis and implementation of effective rehabilitation in individuals with low back and pelvic girdle pain. Therefore, the main objectives of this study were to describe the anatomy of the lateral margin of the TLF, and specifically the interface between the fascial sheath surrounding the paraspinal muscles and the aponeurosis of the transversus abdominis (TA) and internal oblique (IO) muscles. The lateral margin of the TLF was exposed via serial reduction dissections from anterior and posterior approaches. Axial sections (cadaveric and magnetic resonance imaging) were examined to characterize the region between the TA and IO aponeurosis and the paraspinal muscles. It is confirmed that the paraspinal muscles are enveloped by a continuous paraspinal retinacular sheath (PRS), formed by the deep lamina of the posterior layer of the TLF. The PRS extends from the spinous process to transverse process, and is distinct from both the superficial lamina of the posterior layer and middle layer of the TLF. As the aponeurosis approaches the lateral border of the PRS, it appears to separate into two distinct laminae, which join the anterior and posterior walls of the PRS. This configuration creates a previously undescribed fat‐filled lumbar interfascial triangle situated along the lateral border of the paraspinal muscles from the 12th rib to the iliac crest. This triangle results in the unification of different fascial sheaths along the lateral border of the TLF, creating a ridged‐union of dense connective tissue that has been termed the lateral raphe (Spine, 9,1984, 163). This triangle may function in the distribution of laterally mediated tension to balance different viscoelastic moduli, along either the middle or posterior layers of the TLF.

The functional coupling of the deep abdominal and paraspinal muscles: the effects of simulated paraspinal muscle contraction on force transfer to the middle and posterior layer of the thoracolumbar fascia.

The thoracolumbar fascia (TLF) consists of aponeurotic and fascial layers that interweave the paraspinal and abdominal muscles into a complex matrix stabilizing the lumbosacral spine. To better understand low back pain, it is essential to appreciate how these muscles cooperate to influence lumbopelvic stability. This study tested the following hypotheses: (i) pressure within the TLFs paraspinal muscular compartment (PMC) alters load transfer between the TLFs posterior and middle layers (PLF and MLF); and (ii) with increased tension of the common tendon of the transversus abdominis (CTrA) and internal oblique muscles and incremental PMC pressure, fascial tension is primarily transferred to the PLF. In cadaveric axial sections, paraspinal muscles were replaced with inflatable tubes to simulate paraspinal muscle contraction. At each inflation increment, tension was created in the CTrA to simulate contraction of the deep abdominal muscles. Fluoroscopic images and load cells captured changes in the size, shape and tension of the PMC due to inflation, with and without tension to the CTrA. In the absence of PMC pressure, increasing tension on the CTrA resulted in anterior and lateral movement of the PMC. PMC inflation in the absence of tension to the CTrA resulted in a small increase in the PMC perimeter and a larger posterior displacement. Combining PMC inflation and tension to the CTrA resulted in an incremental increase in PLF tension without significantly altering tension in the MLF. Paraspinal muscle contraction leads to posterior displacement of the PLF. When expansion is combined with abdominal muscle contraction, the CTrA and internal oblique transfers tension almost exclusively to the PLF, thereby girdling the paraspinal muscles. The lateral border of the PMC is restrained from displacement to maintain integrity. Posterior movement of the PMC represents an increase of the PLF extension moment arm. Dysfunctional paraspinal muscles would reduce the posterior displacement of the PLF and increase the compliance of the lateral border. The resulting change in PMC geometry could diminish any effects of increased tension of the CTrA. This study reveals a co‐dependent mechanism involving balanced tension between deep abdominal and lumbar spinal muscles, which are linked through the aponeurotic components of the TLF. This implies the existence of a point of equal tension between the paraspinal muscles and the transversus abdominis and internal oblique muscles, acting through the CTrA.

Postnatal Development of Auditory Nerve Projections to the Cochlear Nucleus in Monodelphis Domestica

The external world is represented in the central nervous system by a series of topographic maps or graphs (Changeux,’ 86; Udin and Fawcett,’ 88). These maps are composed of precisely ordered sets of neurons whose organization is a function of the distribution of sensory receptors in the skin, eyes, or ears. Understanding the development of these patterned relationships between the receptor organ and its central pathway is critical to the knowledge of sensory system ontogeny.

The Neuroanatomy of Female Pelvic Pain

The female pelvis is innervated through primary afferent fibers that course in nerves related to both the somatic and autonomic nervous systems. The somatic pelvis includes the bony pelvis, its ligaments, and its surrounding skeletal muscle of the urogenital and anal triangles, whereas the visceral pelvis includes the endopelvic fascial lining of the levator ani and the organ systems that it surrounds such as the rectum, reproductive organs, and urinary bladder. Uncovering the origin of pelvic pain patterns created by the convergence of these two separate primary afferent fiber systems – somatic and visceral – on common neuronal circuitry in the sacral and thoracolumbar spinal cord can be a very difficult process. Diagnosing these blended somatovisceral pelvic pain patterns in the female is further complicated by the strong descending signals from the cerebrum and brainstem to the dorsal horn neurons that can significantly modulate the perception of pain. These descending systems are themselves significantly influenced by both the physiological (such as hormonal) and psychological (such as emotional) states of the individual further distorting the intensity, quality, and localization of pain from the pelvis.

Development of the Mammalian Auditory Hindbrain

Publisher Summary This chapter examines the organization and development of auditory brainstem in mammals. It emphasizes the specificity in laterality of connections in the pathways along with the precision in topographic representation of the basilar membrane seen at multiple levels of the system. It also considers the systems normal development and summarizes the response of the auditory brainstem to peripheral manipulation during maturation. The fundamental organization of the auditory system and its topography are established early in development, well before the onset of stimulus-driven activity. The end-organ experiences early growth and development to accommodate the ossification of the petrous portion of the temporal bone. The auditory nerve quickly grows into the brainstem and establishes its adult-like morphology and adult-like spatial order. The ascending pathways from the cochlear nucleus to the midbrain develop their mature laterality seemingly without forming transient projections to contralateral structures. Within the nuclei of the auditory brainstem, the dendroarchitecture of the Golgi Type I (projection) neurons is evident prior to the onset of stimulus-driven activity.

Ventral Innervation of the Lateral C1–C2 Joint: An Anatomical Study

OBJECTIVE Clinical observation has suggested the presence of ventral cervical extra-articular pain pathways in patients with C1-C2 joint pain. However, the existence of ventral innervation to the C1-C2 joint has not been documented. The objective of this study was to determine whether ventral innervation to the lateral C1-C2 joint exists, and to describe its relational anatomy. DESIGN Gross and microscopic dissection was performed on 11 embalmed human cadavers. Wire segments were placed on identified ventral plexus nerves and radiographic imaging obtained in multiple planes. Histologic staining of prevertebral plexus nerves was performed with Osmium and compared with tissue controls. RESULTS A superficial and deep cervical prevertebral plexus was identified terminating in the ventral joint capsule of the C1-C2 joint in all cadavers examined (21 sides). The location of the deep cervical prevertebral plexus was consistent within the C2 ventral gutter. Osmium staining confirmed the presence of myelin in plexus specimens. CONCLUSION In this study, two cervical prevertebral plexuses (superficial and deep) were identified that have not previously been described. Terminal branches of the plexuses entered the ventral joint capsule of the lateral C1-C2 joint and were seen approaching the dens. Findings provide and explanation for the clinical observation that electrical stimulation in the C2 ventral gutter can reproduce headache in patients with C1-C2 joint pain.