Plexiform hybrid granular cell tumor/perineurioma: a novel variant of benign peripheral nerve sheath tumor with divergent differentiation

The descriptive term hybrid peripheral nerve sheath tumor refers to any neoplasm of the neurilemmal apparatus composed of more than one pathologically defined tumoral equivalent derived from its constituent cells. Within this uncommon nosological category, participation of granular cell tumor - a neoplasm of modified Schwann cells - has been reported only exceptionally. We describe a hitherto not documented variant composed of an organoid mixture of granular cell tumor and perineurioma with plexiform growth. A solitary subcutaneous nodule of 1.5 cm diameter was excised from the right ring finger of a 19-year-old female with no antecedents of neurofibromatosis or relevant trauma. Histology revealed a monotonous, yet cytologically dimorphic proliferation of classical granular cells intermingled with flattened, inconspicuous perineurial cells. Immunohistochemical double labeling detected expression of S100 protein in the former and of EMA and GLUT-1 in the latter. While the respective staining patterns for S100 protein and EMA or GLUT-1 tended to be mutually exclusive, a minority of cells exhibited transitional granular cell/perineurial immunophenotype. Electron microscopy permitted direct visualization of a plethora of lysosomes in the granular cell moiety, and of pinocytotic vesicles and tight junctions in perineurial cells. Intratumoral axons were not detected. Expanding intraneurally, the lesion showed discrete encapsulation by the local perineurium, and resulted in plexiform growth. The MIB-1 labeling index averaged 1%. We interpret our findings as supporting evidence for the dual cell lineage to have arisen through metaplasia, with the tumor's dynamics probably having been driven by the granular cell component.

Incidence of spinal compressive lesions in chondrodystrophic dogs with abnormal recovery after hemilaminectomy for treatment of thoracolumbar disc disease: a prospective magnetic resonance imaging study

OBJECTIVE: To investigate causes of the lack of clinical improvement after thoracolumbar disc surgery. STUDY DESIGN: Case-control magnetic resonance imaging (MRI) study. ANIMALS: Chondrodystrophic dogs with acute thoracolumbar disc disease treated by hemilaminectomy: 10 that had no short-term clinical improvement and 12 with "normal" clinical improvement. METHODS: Dogs that had surgery for treatment of intervertebral disc extrusion (2003-2008) where thoracolumbar disc disease was confirmed by MRI were evaluated to identify dogs that had lack of clinical improvement after surgery. Ten dogs with delayed recovery or clinical deterioration were reexamined with MRI and compared with 12 dogs with normal recovery and MRI reexamination after 6 weeks (control group). RESULTS: Of 173 dogs, 10 (5.8%) had clinical deterioration within 1-10 days after surgery. In 8 dogs, residual spinal cord compression was identified on MRI. Bleeding was present in 1 dog. In 3 dogs, the cause was an incorrect approach and insufficient disc material removal. In 3 dogs, recurrence occurred at the surgical site. In 1 dog, the centrally located extruded material was shifted to the contralateral side during surgery. These 8 dogs had repeat surgery and recovery was uneventful. In 2 dogs, deterioration could not be associated with a compressive disc lesion. Hemorrhagic myelomalacia was confirmed by pathologic examination in 1 dog. The other dog recovered after 6 months of conservative management. CONCLUSION: Delayed postsurgical recovery or deterioration is commonly associated with newly developed and/or remaining compressive disc lesion. CLINICAL RELEVANCE: We recommend early MRI reexamination to assess the postsurgical spinal canal and cord, and to plan further therapeutic measures in chondrodystrophic dogs with delayed recovery after decompressive hemilaminectomy for thoracolumbar disc disease.

Accuracy of ultrasound-guided nerve blocks of the cervical zygapophysial joints

Cervical zygapophysial joint nerve blocks typically are performed with fluoroscopic needle guidance. Descriptions of ultrasound-guided block of these nerves are available, but only one small study compared ultrasound with fluoroscopy, and only for the third occipital nerve. To evaluate the potential usefulness of ultrasound-guidance in clinical practice, studies that determine the accuracy of this technique using a validated control are essential. The aim of this study was to determine the accuracy of ultrasound-guided nerve blocks of the cervical zygapophysial joints using fluoroscopy as control.

Ultrasound-guided suprascapular nerve block, description of a novel supraclavicular approach

The suprascapular nerve (SSN) block is frequently performed for different shoulder pain conditions and for perioperative and postoperative pain control after shoulder surgery. Blind and image-guided techniques have been described, all of which target the nerve within the supraspinous fossa or at the suprascapular notch. This classic target point is not always ideal when ultrasound (US) is used because it is located deep under the muscles, and hence the nerve is not always visible. Blocking the nerve in the supraclavicular region, where it passes underneath the omohyoid muscle, could be an attractive alternative.

Real-time ultrasound-guided spinal anaesthesia: a prospective observational study of a new approach

Identification of the subarachnoid space has traditionally been achieved by either a blind landmark-guided approach or using prepuncture ultrasound assistance. To assess the feasibility of performing spinal anaesthesia under real-time ultrasound guidance in routine clinical practice we conducted a single center prospective observational study among patients undergoing lower limb orthopaedic surgery. A spinal needle was inserted unassisted within the ultrasound transducer imaging plane using a paramedian approach (i.e., the operator held the transducer in one hand and the spinal needle in the other). The primary outcome measure was the success rate of CSF acquisition under real-time ultrasound guidance with CSF being located in 97 out of 100 consecutive patients within median three needle passes (IQR 1-6). CSF was not acquired in three patients. Subsequent attempts combining landmark palpation and pre-puncture ultrasound scanning resulted in successful spinal anaesthesia in two of these patients with the third patient requiring general anaesthesia. Median time from spinal needle insertion until intrathecal injection completion was 1.2 minutes (IQR 0.83-4.1) demonstrating the feasibility of this technique in routine clinical practice.

Ultrasound-guided retrobulbar nerve block in horses: a cadaveric study

Objective  To develop an ultrasound-guided technique for retrobulbar nerve block in horses, and to compare the distribution of three different volumes of injected contrast medium (CM) (4, 8 and 12 mL), with the hypothesis that successful placement of the needle within the retractor bulbi muscle cone would lead to the most effective dispersal of CM towards the nerves leaving the orbital fissure. Study design  Prospective experimental cadaver study. Animals  Twenty equine cadavers. Methods  Ultrasound-guided retrobulbar injections were performed in 40 cadaver orbits. Ultrasound visualization of needle placement within the retractor bulbi muscle cone and spread of injected CM towards the orbital fissure were scored. Needle position and destination of CM were then assessed using computerized tomography (CT), and comparisons performed between ultrasonographic visualization of orbital structures and success rate of injections (intraconal needle placement, CM reaching the orbital fissure). Results  Higher scores for ultrasound visualization resulted in a higher success rate for intraconal CM injection, as documented on the CT images. Successful intraconal placement of the needle (22/34 orbits) resulted in CM always reaching the orbital fissure. CM also reached the orbital fissure in six orbits where needle placement was extraconal. With 4, 8 and 12 mL CM, the orbital fissure was reached in 16/34, 23/34 and 28/34 injections, respectively. Conclusion and clinical relevance  The present study demonstrates the use of ultrasound for visualization of anatomical structures and needle placement during retrobulbar injections in equine orbits. However, this approach needs to be repeated in controlled clinical trials to assess practicability and effectiveness in clinical practice.

Response of the rat spinal cord to X-ray microbeams

BACKGROUND AND PURPOSE: To quantify the late dose-related responses of the rat cervical spinal cord to X-ray irradiations by an array of microbeams or by a single millimeter beam. MATERIALS AND METHODS: Necks of anesthetized rats were irradiated transversely by an 11mm wide array of 52 parallel, 35μm wide, vertical X-ray microbeams, separated by 210μm intervals between centers. Comparison was made with rats irradiated with a 1.35mm wide single beam of similar X-rays. Rats were killed when paresis developed, or up to 383days post irradiation (dpi). RESULTS: Microbeam peak/valley doses of ≈357/12.7Gy to 715/25.4Gy to an 11mm long segment of the spinal cord, or single beam doses of ≈146-454Gy to a 1.35mm long segment caused foreleg paresis and histopathologically verified spinal cord damage; rats exposed to peak/valley doses up to 253/9Gy were paresis-free at 383dpi. CONCLUSIONS: Whereas microbeam radiation therapy [MRT] for malignant gliomas implanted in rat brains can be safe, palliative or curative, the high tolerance of normal rat spinal cords to similar microbeam exposures justifies testing MRT for autochthonous malignancies in the central nervous system of larger animals with a view to subsequent clinical applications.

Mechanisms of symptomatic spinal cord ischemia after TEVAR: insights from the European Registry of Endovascular Aortic Repair Complications (EuREC)

To test the hypothesis that simultaneous closure of at least 2 independent vascular territories supplying the spinal cord and/or prolonged hypotension may be associated with symptomatic spinal cord ischemia (SCI) after thoracic endovascular aortic repair (TEVAR).

Distribution of radiodense contrast medium after perineural injection of the palmar and palmar metacarpal nerves (low 4-point nerve block): an in vivo and ex vivo study in horses

REASONS FOR PERFORMING STUDY: Evidence-based information is limited on distribution of local anaesthetic solution following perineural analgesia of the palmar (Pa) and palmar metacarpal (PaM) nerves in the distal aspect of the metacarpal (Mc) region ('low 4-point nerve block'). OBJECTIVES: To demonstrate the potential distribution of local anaesthetic solution after a low 4-point nerve block using a radiographic contrast model. METHODS: A radiodense contrast medium was injected subcutaneously over the medial or the lateral Pa nerve at the junction of the proximal three-quarters and distal quarter of the Mc region (Pa injection) and over the ipsilateral PaM nerve immediately distal to the distal aspect of the second or fourth Mc bones (PaM injection) in both forelimbs of 10 mature horses free from lameness. Radiographs were obtained 0, 10 and 20 min after injection and analysed subjectively and objectively. Methylene blue and a radiodense contrast medium were injected in 20 cadaver limbs using the same techniques. Radiographs were obtained and the limbs dissected. RESULTS: After 31/40 (77.5%) Pa injections, the pattern of the contrast medium suggested distribution in the neurovascular bundle. There was significant proximal diffusion with time, but the main contrast medium patch never progressed proximal to the mid-Mc region. The radiological appearance of 2 limbs suggested that contrast medium was present in the digital flexor tendon sheath (DFTS). After PaM injections, the contrast medium was distributed diffusely around the injection site in the majority of the limbs. In cadaver limbs, after Pa injections, the contrast medium and the dye were distributed in the neurovascular bundle in 8/20 (40%) limbs and in the DFTS in 6/20 (30%) of limbs. After PaM injections, the contrast and dye were distributed diffusely around the injection site in 9/20 (45%) limbs and showed diffuse and tubular distribution in 11/20 (55%) limbs. CONCLUSIONS AND POTENTIAL RELEVANCE: Proximal diffusion of local anaesthetic solution after a low 4-point nerve block is unlikely to be responsible for decreasing lameness caused by pain in the proximal Mc region. The DFTS may be penetrated inadvertently when performing a low 4-point nerve block.

The effects of isoflurane minimum alveolar concentration on withdrawal reflex activity evoked by repeated transcutaneous electrical stimulation in ponies

The aim of this study was to quantify the effects of isoflurane at approximately the minimum alveolar concentration (peri-MAC) on the temporal summation (TS) of reflex activity in ponies. TS was evoked by repeated electrical stimulations applied at 5 Hz for 2 s on the digital nerve of the left forelimb of seven ponies. Surface electromyographic activity was recorded from the deltoid and common digital extensor muscles. TS thresholds and amplitude of response to stimulations of increasing intensities were assessed during anaesthesia at 0.85, 0.95 and 1.05 times the individual MAC, and after anaesthesia in standing animals. Under isoflurane anaesthesia, TS thresholds increased significantly in a concentration-dependent fashion and at each isoflurane MAC, the responses increased significantly for increasing stimulation intensities. A concentration-dependent depression of evoked reflexes with a reduction in the slopes of the stimulus-response function was observed for both muscles. The results demonstrated that with this model it is possible to describe and quantify the effects of anaesthetics on spinal sensory-motor processing in ponies.

Predictors of surgical, general and follow-up complications in lumbar spinal stenosis relative to patient age as emerged from the Spine Tango Registry

Published opinions regarding the outcomes and complications in older patients have a broad spectrum and there is a disagreement whether surgery in older patients entails a higher risk. Therefore this study examines the risk of surgery for lumbar spinal stenosis relative to age in the pooled data set of the Spine Tango registry.