Radiography and biomechanics of sixth and seventh cervical vertebrae segments after disc fenestration and after insertion of an intervertebral body spacer. A canine cadaveric study

OBJECTIVES

To study the radiographic characteristics and the biomechanical properties of the sixth and seventh cervical (C6-C7) vertebral motion unit (VMU) with an intact disc, after disc fenestration, and after placement of an intervertebral body spacer (IVBS).

METHODS

Six cadaveric C6-C7 VMU were retrieved from six Greyhound cadavers. Each VMU was loaded at 3 Nm of torque sequentially in flexion, extension, and in right and left lateral bending. The range-of-motion (ROM) was measured with a Zebris 3D® system. The intervertebral disc cross-sectional area was measured on lateral and ventro-dorsal radiographs. Biomechanical testing and radiographic measurements were performed with an intact disc, after disc fenestration, and after IVBS placement. Data were reported as mean±SD.

RESULTS

The intervertebral disc cross-sectional area was significantly decreased after disc fenestration and increased after IVBS placement, but remained significantly smaller than the area of intact disc in some of the tested conditions. The ROM with an intact disc, after disc fenestration and after IVBS placement, in flexion were 11.5°±1.0, 15.2°±2.3, and 10.9°±4.7, respectively, and in extension were 15.6°±3.7, 24.7°±6.2, 21.9°±4.0, respectively. There was a significant increase in extension ROM after disc fenestration. Intervertebral body spacer placement significantly decreased ROM in flexion but ROM in extension was not different from disc fenestration. No significant changes in lateral bending ROM were detected.

CLINICAL SIGNIFICANCE

The use of an IVBS reduced disc space collapse but did not restore stability of the VMU to normal values in extension after cervical disc fenestration.

MDCTA diagnosis of cerebral vessel disease among patients with arterial hypertension

Background:

to study changes involving cerebral vessels in patients with hypertension and various levels of total cardiovascular risk.

Material/Methods:

One hundred and thirty-four patients underwent CT-angiography of intracranial vessels. Ninety-eight of them were diagnosed with hypertension. Taking into consideration high blood pressure, presence of risk factors and target organ damage subjects were divided into 4 groups: with low, medium, high and very high total cardiovascular risk. Control group included 36 patients. They were not diagnosed with hypertension at the time of examination. One hundred and five patients were examined using a 4-slice CT scanner (Toshiba Asteion 4, Toshiba Medical System, Japan), and 29 patients were examined using a 128-slice scanner (Siemens Definition AS+, Siemens Healthcare, Germany) with an injection system. We used iodine-containing contrast agents such as iodixanol and iopromide for angiography.

Results:

Anatomical and topographic changes of cerebral vessels were most frequently found in hypertensive patients with high and very high total cardiovascular risk. Narrowing of vertebral vessels was the most common change (27 patients (27.55%), 21 patients (21.43%) had narrowing of the right artery, and 6 (6.12%) subjects – of the left one). Tortuous course of internal carotid arteries at the neck level was visualized in 11 patients (11.22%). Narrowing of A1 segment of anterior cerebral artery was noted in 9 patients (9.18%), of the right one – in 8 patients (8.16%), of the left one – in 1 patient (1.02%). Aneurysmal dilation of intracranial vessels was visualized in 6 patients (6.12%). Saccular aneurysm of left internal carotid artery was diagnosed in 2 patients (2.04%), one patient (1.02%) had right internal carotid artery aneurysm and one patient (1.02%) had an aneurysm of the basilar artery.

Discussions:

the most common changes of cerebral vessels diagnosed in MDCTA among patients with hypertension included various degrees of narrowing of vertebral vessels, anterior, posterior and posterior communicating arteries and internal carotid arteries. Changes of middle cerebral arteries and basilar arteries were extremely rare, thus we can say that these vessels are influenced by high blood pressure to lesser extent. We established the relationship between changes in cerebral blood vessels and total cardiovascular risk. Therefore, we believe that findings will be useful for establishing prognosis in hypertension and prevention of complications such as stroke.

Conclusions:

MDCT angiography is a highly informative method to study changes of cerebral vessels in patients with hypertension. The relationship between changes in cerebral blood vessels diagnosed through MDCT angiography and the level of total cardiovascular risk among patients with hypertension had been established.

Fenestration and duplication of the vertebral artery: the anatomical and clinical points of view

The vertebral artery (VA) acts as a foundation for the posterior circulation of the head and neck. It presents a number of anomalies that can be easily visualized thanks to modern imaging techniques, such as MR and CT angiography or color Doppler ulrasonography. Determining the appropriate terminology for those anomalies can be sometimes more challenging than their recognition. One particular challenge concerns the differentiation between VA fenestration and duplication. Because of the different clinical prognoses associated with those anomalies, confusion should be avoided. Knowledge of the morphological anomalies associated with the VA is important for both radiologists and head and neck surgeons, because any injury to the VA can result in a threat to the vascular supply of the brain stem, the cerebral or cerebellar hemispheres, the thalamus, cervical nerve roots and particularly the lateral medulla (Wallenberg's syndrome). This article analyses world literature concerning the issue of VA fenestration and duplication to facilitate a differential diagnosis.

Role of differentiation of liver sinusoidal endothelial cells in progression and regression of hepatic fibrosis in rats

BACKGROUND & AIMS

Capillarization, characterized by loss of differentiation of liver sinusoidal endothelial cells (LSECs), precedes the onset of hepatic fibrosis. We investigated whether restoration of LSEC differentiation would normalize crosstalk with activated hepatic stellate cells (HSC) and thereby promote quiescence of HSC and regression of fibrosis.

METHODS

Rat LSECs were cultured with inhibitors and/or agonists and examined by scanning electron microscopy for fenestrae in sieve plates. Cirrhosis was induced in rats using thioacetamide, followed by administration of BAY 60-2770, an activator of soluble guanylate cyclase (sGC). Fibrosis was assessed by Sirius red staining; expression of α-smooth muscle actin was measured by immunoblot analysis.

RESULTS

Maintenance of LSEC differentiation requires vascular endothelial growth factor-A stimulation of nitric oxide-dependent signaling (via sGC and cyclic guanosine monophosphate) and nitric oxide-independent signaling. In rats with thioacetamide-induced cirrhosis, BAY 60-2770 accelerated the complete reversal of capillarization (restored differentiation of LSECs) without directly affecting activation of HSCs or fibrosis. Restoration of differentiation to LSECs led to quiescence of HSCs and regression of fibrosis in the absence of further exposure to BAY 60-2770. Activation of sGC with BAY 60-2770 prevented progression of cirrhosis, despite continued administration of thioacetamide.

CONCLUSIONS

The state of LSEC differentiation plays a pivotal role in HSC activation and the fibrotic process.

Allosteric modulation of Ca2+ flux in ligand-gated cation channel (P2X4) by actions on lateral portals

Human P2X receptors are a family of seven ATP-gated ion channels that transport Na(+), K(+), and Ca(2+) across cell surface membranes. The P2X4 receptor is unique among family members in its sensitivity to the macrocyclic lactone, ivermectin, which allosterically modulates both ion conduction and channel gating. In this paper we show that removing the fixed negative charge of a single acidic amino acid (Glu(51)) in the lateral entrance to the transmembrane pore markedly attenuates the effect of ivermectin on Ca(2+) current and channel gating. Ca(2+) entry through P2X4 receptors is known to trigger downstream signaling pathways in microglia. Our experiments show that the lateral portals could present a novel target for drugs in the treatment of microglia-associated disease including neuropathic pain.

Dehiscence and fenestration in skeletal Class I, II, and III malocclusions assessed with cone-beam computed tomography

OBJECTIVE

To test the null hypothesis that the presence of dehiscence and fenestration was not different among patients with skeletal Class I, II, and III malocclusions.

MATERIALS AND METHODS

In this retrospective study, a total of 123 cone-beam computed tomography (CBCT) images were obtained with an iCAT scanner (Imaging Sciences International, Hatfield, Pa). Patients with normal vertical patterns were classified according to dental malocclusion and ANB angle. Class I comprised 41 patients-21 girls and 20 boys (mean age, 22.4 ± 4.5 years); Class II comprised 42 patients-22 girls and 20 boys (mean age, 21.5 ± 4.2 years); and Class III comprised 40 subjects-22 girls and 18 boys (mean age, 22.1 ± 4.5 years). A total of 3444 teeth were evaluated. Analysis of variance and Tukey's test were used for statistical comparisons at the P < .05 level.

RESULTS

Statistical analysis indicated that the Class II group had a greater prevalence of fenestration than the other groups (P < .001). No difference was found in the prevalence of dehiscence among the three groups. Although fenestration had greater prevalence in the maxilla, more dehiscence was found in the mandible for all groups. In Class I, alveolar defects (dehiscence, fenestration) were matched relatively in both jaws. Furthermore, Class II and Class III subjects had more alveolar defects (41.11% and 45.02%, respectively) in the mandible. Dehiscences were seen with greater frequency in the mandibular incisors of all groups.

CONCLUSION

The null hypothesis was rejected. Significant differences in the presence of fenestration were found among subjects with skeletal Class I, Class II, and Class III malocclusions. Fenestrations had greater prevalence in the maxilla, but more dehiscences were found in the mandible.

Endovascular coil embolization for ruptured kissing aneurysms associated with A1 fenestration

Background:

Fenestration of intracranial arteries is a rare anomaly, and is frequently associated with cerebral aneurysms. In this paper, we report rare kissing aneurysms associated with A1 fenestration.

Case Description:

A 71-year-old woman presented with subarachnoid hemorrhage. Diagnostic digital subtraction angiography revealed two saccular aneurysms at the proximal junction of a fenestration and posterior aspect of the fenestration that appeared to be ‘kissing’ each other. Emergent endovascular coil embolization was performed.

Conclusion:

Kissing aneurysms associated with fenestration of the horizontal segment in the anterior cerebral artery are rare, and have not been reported. During treatment of such specific types of aneurysms by endovascular treatment, three-dimensional rotational digital subtraction angiography was very useful for deciding the appropriate working angles.

Optic nerve sheath fenestration in cryptococcal meningitis

A patient with acquired immunodeficiency syndrome (AIDS) developed crytpococcal meningitis, complicated by papilledema and severe progressive visual loss despite medical therapy. Bilateral optic sheath fenestration resulted in significant improvement in vision and resolution of papilledema. Histopathologic evaluation of the optic nerve sheath demonstrated numerous cryptococci. Optic nerve sheath fenestration may be an effective treatment method when high intracranial pressure is contributing to visual loss, even in the presence of involvement of the optic nerve sheath by the fungus.

Clinical and radiological instability following standard fenestration discectomy

BACKGROUND

Post-surgical lumbar instability is an established complication but there is limited evidence in the literature regarding the incidence of lumbar instability following fenestration and discectomy. We analyzed our results following fenestration discectomy with a special focus on instability.

MATERIALS AND METHODS

Eighty-three patients between the age of 17 and 52 years who had undergone fenestration discectomy for a single-level lumbar intervertebral disc prolapse were followed-up for a period of 1-5 years. The criteria for instability included "instability catch,", "painful catch," and "apprehension." The working capacity of the patient and the outcome score of the surgery were assessed by means of the Oswestry disability score and the Prolo economic and functional outcome score. Flexion-extension lateral radiographs were taken and analyzed for abnormal tilt and translation.

RESULTS

Of the 83 patients included, 70 were men and 13 were women, with an average age of 37.35 years (17-52 years) at 5 years follow-up. Clinical instability was seen in 10 (12.04%) patients. Radiological instability was noted in 29 (34.9%) patients. Only six (60%) of the 10 patients who demonstrated clinical instability had radiological evidence of instability. Twenty (68.96%) patients with radiological instability were asymptomatic. Three (10.34%) patients with only radiological instability had unsatisfactory outcome. The Oswestry scoring showed an average score of 19.8%. Mild disability was noted in 59 (71.08%) patients and moderate disability was seen in 24 (28.91%) patients. None of the patients had severe disability. These outcomes were compared with the outcomes in other studies in the literature for microdiscectomy and the results were found to be comparable.

CONCLUSION

The favorable outcome of this study is in good agreement with other studies on microdiscectomy. Clinical instability in 12.04% of the patients is in agreement with other studies. Radiological signs of instability are seen even in asymptomatic patients and so are not as reliable as clinical signs of instability. Standard fenestration discectomy does not destabilize the spine more than microdiscectomy.

The response of fenestrations, actin, and caveolin-1 to vascular endothelial growth factor in SK Hep1 cells

To study the regulation of fenestrations by vascular endothelial growth factor in liver sinusoidal endothelial cells, SK Hep1 cells were transfected with green fluorescence protein (GFP)-actin and GFP-caveolin-1. SK Hep1 cells had pores; some of which appeared to be fenestrations (diameter 55 +/- 28 nm, porosity 2.0 +/- 1.4%), rudimentary sieve plates, bristle-coated micropinocytotic vesicles and expressed caveolin-1, von Willebrand factor, vascular endothelial growth factor receptor-2, endothelial nitric oxide synthase and clathrin, but not CD31. There was avid uptake of formaldehyde serum albumin, consistent with endocytosis. Vascular endothelial growth factor caused an increase in porosity to 4.8 +/- 2.6% (P < 0.01) and pore diameter to 104 +/- 59 nm (P < 0.001). GFP-actin was expressed throughout the cells, whereas GFP-caveolin-1 had a punctate appearance; both responded to vascular endothelial growth factor by contraction toward the nucleus over hours in parallel with the formation of fenestrations. SK Hep1 cells resemble liver sinusoidal endothelial cells, and the vascular endothelial growth factor-induced formation of fenestration-like pores is preceded by contraction of actin cytoskeleton and attached caveolin-1 toward the nucleus.

Degenerative lumbar spinal stenosis: current strategies in diagnosis and treatment

INTRODUCTION

Although the aging of the population is causing a dramatic rise in the incidence of lumbar spinal stenosis, the indications and options for surgical treatment are not clearly defined.

METHODS

In an attempt to aid clinical decision making, a selective literature review was conducted, taking into account the guidelines of the Association of the Scientific Medical Societies in Germany (AWMF).

RESULTS

In degenerative lumbar spinal stenosis hypertrophy of the facet joints and yellow ligaments brings about constriction of the spinal canal, leading to back pain and activity-dependent lower limb symptoms (neurogenic claudication). If conservative treatment fails, an imaging study, usually magnetic resonance imaging, is required. In the case of severe symptoms the progressive underlying degeneration necessitates surgical treatment. Minimally invasive fenestration techniques are usually employed to decompress the spinal canal; in the presence of instability, fusion is indicated.

DISCUSSION

Despite the proven superiority of surgery in the management of refractory lumbar spinal stenosis, there is a lack of evidence-based data regarding the different surgical treatment options. The evaluation of modern, minimally invasive techniques is thus difficult.

Transcatheter closure of fenestration with detachable coils after the Fontan operation

We report our experience in 13 patients who underwent transcatheter closure of Fontan fenestration with the Cook detachable coils. These patients underwent the extracardiac type Fontan operation with a short conduit fenestration (n=7) or lateral tunnel type with a punch-hole fenestration (n=6). Fenestration closure was done at the mean age of 5.1+/-2.4 yr, average of 32 months after the Fontan operation. We used one to three coils depending on the fenestration type, size, and residual shunt. Aortic oxygen saturations increased by an average of 5.4 (2-9)% and mean pressures in the Fontan circuit increased by an average of 2.1 (0-6) mmHg. During follow-up (median of 23 months), five patients (4 in extracardiac, 1 in lateral tunnel) had complete occlusion of the fenestration on echocardiography. There was no immediate or late complication. Transcatheter closure of fenestration in Fontan operation using the Cook detachable coil is a safe and feasible technique. However, the coil was ineffective for closure of a punch-hole fenestration in the lateral tunnel type operation. In the conduit type fenestration, some modification of fenestration method instead of a short conduit for coil closure or use of new device is necessary to increase complete closure rate.

Hepatobiliary cystadenoma: diagnostic uncertainty

BACKGROUND

Hepatobiliary cystadenoma is a rare tumour that can be clinically 'silent' and only discovered as an incidental finding on ultrasonography (US). It can also be symptomatic with abdominal pain and jaundice or develop internal bleeding and (exceptionally) malignant degeneration. Therefore the treatment of choice is liver resection.

CASE OUTLINE

A 77-year-old woman was admitted with mild jaundice and right hypochondrial pain. For 7 years she had been known to have a silent liver lesion, always considered to be a simple cyst on US. US and CT scan revealed a multi-septate mass involving segments IV, V and VIII of the liver, with thick walls, no calcifications and no contrast enhancement. US-guided aspiration showed the presence of old blood-stained material. The patient was operated with a suspected diagnosis of bleeding into a simple cyst. A Lin fenestration was performed with wide excision of the anterior wall of the cyst. Pathological examination demonstrated a mucinous hepatobiliary cystadenoma. The postoperative course was uneventful, and follow-up at 2 years confirmed no recurrence.

DISCUSSION

Imaging will normally help to distinguish the occasional hepatobiliary cystadenoma from the common simple cyst. Otherwise, when a complication occurs, preoperative differentiation may become impossible, and requires histological examination of the cyst after surgical removal.