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Concept: Epidural space


Low back pain is very common, but the pathophysiology is poorly understood. We present a new hypothesis regarding the pathophysiology of common low back pain supported by our flexible endoscopic observations of the epidural cavity (epiduroscopy), anatomic dissection of embalmed and fresh cadavers, and careful review of preexisting information available on the anatomy of the epidural space and neuroforamen. A new approach to the treatment of common low back pain based on the hypothesis was developed and is presented in the case reports of five patients. Treatment focuses on a perichondrium derivative; the peridural membrane, which creates a suprapedicular compartment in the neuroforamen where we hypothesize inflammatory material accumulates. This produces common low back pain by causing inflammation and sensitization of the peridural membrane and periosteum that forms the boundaries of this compartment. Percutaneous Ablation and Curettage and Inferior Foraminotomy (PACIF(sm) ) aims to destroy the peridural membrane, denervate sensitive structures, and remove inflammatory tissues from the suprapedicular canal. The proposed mechanism of action and safety of PACIF(sm) is discussed in the context of epidural and neuroforaminal anatomy. As shown by the five case reports, PACIF(sm) appears to be highly effective and safe, warranting further evaluation.

Concepts: Back pain, Low back pain, Observation, Scientific method, Epidural space, Epidural, Dissection


Maintaining the integrity of the capsule along with infusing a sufficient amount of fluid is one of the therapeutic concept in intra-articular hydraulic distension (IHD) for adhesive capsulitis. It has been known that hypertonic saline decreases tissue edema and increases the fluid volume within the epidural space, causing microdissection, in epidural adhesiolysis.

Concepts: Epidural space, Laser capture microdissection, Epidural, Concepts in metaphysics, Hydrodilatation, Adhesive capsulitis of shoulder


We describe a patient who received an unintentionally prolonged epidural infusion of phenylephrine. The patient experienced no major morbidity. However, this case highlights the continuing problem of wrong-route drug administration and the urgent need to adopt route-specific connections.

Concepts: Miracles, Illness, Epidural space, Infusion pump, Patient, Epidural


BACKGROUND:Epidural steroid injections are commonly used for management of low back pain with lumbosacral radicular pain and can be administered by either interlaminar or transforaminal routes. The transforaminal route is reported to be more effective than the interlaminar route due to higher delivery of drug at the ventral epidural space. However, the transforaminal route has been associated with serious complications including spinal cord injury and permanent paralysis. Hence, there is a search for a technically better route with fewer complications for drug delivery into the ventral epidural space. Recently, a parasagittal interlaminar (PIL) approach of epidural contrast injection was reported to have 100% ventral epidural spread. However, the therapeutic efficacy of this route has never been investigated. We compared the therapeutic efficacy of the PIL approach and midline interlaminar (MIL) approach. We hypothesized that the PIL approach may produce a better clinical outcome because of better ventral epidural spread of the drug compared with MIL approach.METHODS:Thirty-seven patients were randomized to receive injection of 80 mg methylprednisolone either by the PIL (PIL group, n = 19) or MIL (MIL group, n = 18) approach under fluoroscopic guidance. Patients were evaluated for effective pain relief (≥50% from baseline) by visual analog scale and improvement in disability by the modified Oswestry Disability Questionnaire at intervals of 15 days, 1, 2, 3, and 6 months. Patients having <50% pain relief from baseline received additional epidural injection of the same drug, dosage, and route, a maximum of 3 injections at least 15 days apart. The primary outcome of our study was the incidence of effective pain relief at 6 months.RESULTS:The incidence of patients having effective pain relief was higher with the PIL approach (13/19 [68.4%]) vs MIL (3/18 [16.7%]) at the end of 6 months. A significantly higher relative success of effective pain relief was noted in the PIL group (relative risk, 4.10; 95% confidence interval, 1.40-12.05; P = 0.001) at the end of the 6-month follow up with the requirement of fewer total injections (29 vs 41 in MIL, P = 0.043). Visual analog scale and modified Oswestry Disability Questionnaire scores were significantly lower in the PIL group compared with the MIL group at all time intervals after the procedure. Ventral epidural spread of contrast was significantly higher in the PIL 89.7% vs 31.7% in the MIL group. The administration of epidural steroid injection was without any complications with an exact 95% Clopper-Pearson confidence interval of 0.0% to 17.6% in the PIL group and 0.0% to 18.5% in the MIL group.CONCLUSIONS:Epidural steroid injection administered with the PIL approach was significantly more effective for pain relief and improvement in disability than the MIL approach for 6 months in the management of low back pain with lumbosacral radicular pain.

Concepts: Spinal cord, Acupuncture, Pain, Epidural space, Low back pain, Efficacy, Spinal disc herniation, Epidural


Evaluate the efficacy and safety of MESNA (sodium 2-mercaptoethanesulfonate) injection into the epidural space in the FBSS.

Concepts: Epidural space, Failed back syndrome, Epidural


Ablation of paraspinal lesions close to the spinal canal and neuroforamina requires protective measures in order to protect the spinal cord and nerve roots. Various methods of protection have been previously described including infusion of saline and CO2. Regardless, neuromonitoring should be adjunctively performed when ablating spinal lesions close to neuronal structures. Balloon protection has been previously described during ablation of renal masses. The benefit of balloon protection in paraspinal mass ablation is it physically displaces the nerve roots as opposed to CO2 or saline which has the potential to insulate but because of its aerosolized or fluid nature may or may not provide definitive continuous protection throughout an ablation. This report details three paraspinal lesions, two of which were successfully ablated with the use of a balloon placed in the epidural space to provide protection to the spinal cord and nerve roots.

Concepts: Sublimation, Mass, Spinal cord, Spinal canal, Subarachnoid space, Epidural space, Neuron, Protection


Lumbar disk herniation is common. Because of the posterior longitudinal ligament, migration usually occurs into the ventral epidural space. Rarely, fragments migrate into the dorsal epidural space. A 57-year-old man presented with lower back pain and weakness on right hip flexion and right knee flexion. He had lower back pain 1 day previously and received a transforaminal epidural block at a local hospital. The next day, he reported weakness of the right lower extremity. Lumbar spine magnetic resonance imaging revealed a dorsal epidural lesion with compression of the thecal sac at L2-3. Initial differential diagnoses included epidural hematoma after the block, neoplasm, and a sequestrated disk. Posterior lumbar decompression was performed. The lesion was identified intraoperatively as a large herniated disk fragment. Posterior epidural herniation of a lumbar disk fragment is rare and may be difficult to diagnose preoperatively. It may present as a variety of clinical scenarios and, as in this case, may mimic epidural hematoma.

Concepts: Low back pain, Knee, Hernia, Neurology, Magnetic resonance imaging, Epidural space, Epidural, Spinal disc herniation


Although the etiology of spontaneous spinal epidural hematoma (SSEH) is unclear, SSEH is known to be associated with anticoagulants, coagulopathy, vascular malformation, hypertension, and pregnancy. However, no report has been issued on the relation between SSEH and venous phlebolith. Here, the authors present an extremely rare case of SSEH associated with phlebolith in the cervical spine and suggest a possible pathogenesis. A 36-year-old man without any relevant medical history presented with neck pain and numbness and severe radiating pain on the left arm. Magnetic resonance imaging showed epidural hematoma at the C5-7 level, and computed tomography revealed a calcified nodule in the left epidural hemorrhage at C6 level. During left partial laminectomy, epidural venous plexus, and thick epidural hematoma were found, and hematoma removal revealed a white, ovoid, smooth, hard mass of diameter 3 mm. Histopathologic examination confirmed the mass as a venous phlebolith. The presence of a calcified solitary nodule in dorsal epidural space indicates the presence of phlebolith and the risk of SSEH. In such cases, the authors recommend spine surgeons should take into consideration the possibility of epidural hemorrhage.

Concepts: Cervical vertebrae, Subdural hematoma, Epidural space, Magnetic resonance imaging, Medical imaging, Vertebral column, Epidural hematoma, Epidural


Ultrasound guidance for epidural block has improved clinical blind-trial problems but the design of present ultrasonic probes poses operating difficulty of ultrasound-guided catheterization, increasing the failure rate. The purpose of this study was to develop a novel ultrasonic probe to avoid needle contact with vertebral bone during epidural catheterization. The probe has a central circular passage for needle insertion. Two focused annular transducers are deployed around the passage for on-axis guidance. A 17-gauge insulated Tuohy needle containing the self-developed fiber-optic-modified stylet was inserted into the back of the anesthetized pig, in the lumbar region under the guidance of our ultrasonic probe. The inner transducer of the probe detected the shallow echo signals of the peak-peak amplitude of 2.8 V over L3 at the depth of 2.4 cm, and the amplitude was decreased to 0.8 V directly over the L3 to L4 interspace. The outer transducer could detect the echoes from the deeper bone at the depth of 4.5 cm, which did not appear for the inner transducer. The operator tilted the probe slightly in left-right and cranial-caudal directions until the echoes at the depth of 4.5 cm disappeared, and the epidural needle was inserted through the central passage of the probe. The needle was advanced and stopped when the epidural space was identified by optical technique. The needle passed without bone contact. Designs of the hollow probe for needle pass and dual transducers with different focal lengths for detection of shallow and deep vertebrae may benefit operation, bone/nonbone identification, and cost.

Concepts: Focal length, Hypodermic needle, Piezoelectricity, Spinal cord, Epidural space, Catheter, Tuohy needle, Epidural


An enterogenous cyst is a rare entity categorized as an intestinal cyst. In most cases, enterogenous cysts are seen in the mediastinum, peritoneal cavity, spinal canal, subarachnoid space, and cerebral ventricle.

Concepts: Cerebral cortex, Epidural space, Spinal cord, Cerebrospinal fluid