Mechanical Thrombectomy for Treatment of Cerebral Venous Sinus Thrombosis in Vaccine-Induced Immune Thrombotic Thrombocytopenia.

Reports of a rare form of cerebral venous sinus thrombosis with profound thrombocytopenia have emerged following introduction of the adenovirus-vectored coronavirus disease 2019 (COVID-19) vaccines. Between March and June 2021, seven cases of refractory vaccine-induced immune thrombotic thrombocytopenia were referred to our institution for mechanical thrombectomy. The condition of 1 patient deteriorated during interhospital transfer, and the remaining 6 underwent successful recanalization. No procedure-related adverse events were reported. At the time of this writing, 3 patients have been discharged with a good functional outcome (mRS 0-1), one required rehabilitation for mild dysarthria and vocal cord palsy (mRS 3), and 2 have died due to severe mass effect. Our anecdotal experience suggests that endovascular therapy may be safe and effective in reducing thrombus burden in selected cases of postvaccination cerebral venous sinus thrombosis.

Learning and retaining simulated arthroscopic meniscal repair skills.

BACKGROUND: Previous studies of task-specific skills have suggested that a loss of technical performance occurs if the skill is not practiced for a six-month period. The aims of this study were to objectively demonstrate the learning curve for a complex arthroscopic task (meniscal repair) by means of motion analysis and to determine the impact of task repetition on the retention of this skill. METHODS: Nineteen orthopaedic residents with experience in routine knee arthroscopy but not in arthroscopic meniscal repair were recruited into a randomized study. During the initial learning phase, all subjects performed twelve meniscal repairs on a knee simulator over a three-week period. A validated motion analysis tracking system was used to objectively record the performance and learning of each subject; the outcomes were the time taken, distance traveled, and number of hand movements. The subjects were then randomized into three groups. Group A performed one meniscal repair each month, Group B performed one meniscal repair at three months, and Group C performed no repairs during this interim phase. All three groups then returned at the six-month point for the final assessment phase, during which they carried out an additional twelve meniscal repairs over three weeks. RESULTS: All subjects demonstrated a clear learning curve during the initial learning phase, with significant objective improvement in all motion analysis parameters over the initial twelve episodes (p < 0.0001). Although some residents had reached a learning plateau by twelve episodes, others continued to make further improvements for up to another nine episodes. Importantly, Group C did not display any loss of skill between the initial learning phase and final evaluation phase despite a six-month break in task repetition (p > 0.05). CONCLUSIONS: In contrast to previous studies, residents did not lose any skill over a six-month interruption in task performance, and other residents took longer to produce a more consistent performance.

Simple visual parameters for objective assessment of arthroscopic skill.

BACKGROUND: Restrictions placed on the working hours of doctors over the past decade have resulted in substantial changes to the training and assessment of orthopaedic surgical residents. Many who are responsible for training the surgeons of the future have become concerned that this reduced clinical exposure is having a detrimental impact on technical skill acquisition. Consequently, there is a need for surgical educators to develop more objective methods for assessing surgical skill. The primary aim of this study was to determine whether a novel set of visual parameters assessing visuospatial ability, fine motor dexterity, and gaze control could objectively discriminate among various levels of arthroscopic experience. The secondary aim was to evaluate the correlations between these new parameters and previously established technical skill assessment methods. METHODS: Twenty-seven subjects were divided into a novice group (n = 7), a resident group (n = 15), and an expert group (n = 5) on the basis of arthroscopic experience. All subjects performed a diagnostic knee arthroscopy task on a simulator. Their performance was assessed with use of novel simple visual parameters that included the prevalence of instrument loss, triangulation time, and prevalence of lookdowns. Performance was also evaluated with use of previously validated technical skill assessment methods (a global rating scale and motion analysis). RESULTS: A significant difference in performance among the groups was demonstrated with use of all three novel visual parameters, the global rating scale, and motion analysis (p < 0.05). There were strong and highly significant correlations (p < 0.0001) between each of the novel parameters and the previously validated skill assessment methods. CONCLUSIONS: This study demonstrates the construct validity of three novel visual parameters for objectively assessing arthroscopic performance. These parameters are simple, can be used easily in the operating room, and are strongly correlated with current validated methods of technical skill assessment.

Anatomical and surgical considerations of the external branch of the superior laryngeal nerve: a systematic review.

The anatomical course of the external branch of the superior laryngeal nerve (EBSLN) is variable, and a consistent approach to its preservation during thyroid surgery is needed to reduce risk of post-operative voice impairment. Despite agreement that careful dissection in the region of the superior thyroid pole is required, there is no accepted 'best' approach, nor any universal acknowledgement that location of the EBSLN is actually necessary. The popular cernea classification of EBSLN has limitations, including its decreased reliability with increased thyroid size and its irrelevance in cases of 'buried' variants. * Recent work has identified factors such as ethnicity and stature in the prevalence of EBSLN variants. Consistent approaches to the post-operative detection of EBSLN injury are needed to build an accurate picture of the incidence of surgical nerve injury. Then a standardised approach to EBSLN preservation may emerge.

Ultrastructural changes in rat livers perfused in vitro and in vivo with a high dose of methotrexate.

Methotrexate is an antifolate that is widely used in the treatment of malignant tumours and other diseases. The present study was undertaken to examine the short-term effects of high doses of methotrexate (HD-MTX) on the ultrastructure and metabolic activity of isolated rat livers. The authenticity of the drug-induced changes was substantiated by the concomitant use of in vivo experiments. Isolated rat livers were infused with HD-MTX via the portal vein for 3 hours (total dose for each liver 2000 mg). For in vivo experiments, each rat received a single intravenous injection of a maximum tolerated dose of MTX (100 mg/kg body weight) that allowed the animals to survive for 3 days. At the end of each experimental period, MTX-treated and control livers were processed for light microscopy (LM), scanning (SEM) and transmission electron (TEM) microscopy. Oxygen consumption and thyroxine metabolism were measured in treated and control isolated livers. With the exception of a few minor differences, the structural changes in the hepatocytes after MTX treatment in vitro and vivo were similar. There were focal changes consisting of disruption of normal hepatic plates and swelling and vacuolation of the hepatocytes, with no clear evidence of restriction to a specific hepatic zone. SEM revealed striking changes in the plasma membrane, the microvillar system, intercellular junctions and the sinusoidal endothelium. TEM revealed disorganized endoplasmic reticulum, dispersion of the polyribosomes, a variety of mitochondrial changes, and glycogen redistribution. In MTX-treated isolated rat livers, the uptake of tetraiodothyronine (T4) was not affected, but triiodothyronine (T3) release was impaired. Oxygen consumption was increased in livers treated with MTX. Employing an organotypic liver perfusion model in conjunction with the in vivo experiment and the use of SEM, TEM and hepatic thyroxine measurements, this investigation revealed that infusion of HD-MTX induced early ultrastructual changes in cell membrane, intercellular junctions and cell organelles and disturbance in the functional integrity of the hepatocytes in isolated rat liver.

The iliopubic tract: an important anatomical landmark in surgery.

A band of fascial thickening, termed the iliopubic tract, lies on the posterior aspect of the inguinal region and has been described in the surgical literature as playing an important role during herniorraphy. This study was undertaken to examine the gross and microscopic anatomy of the iliopubic tract in 12 cadavers. The results confirmed that the iliopubic tract can be readily identified as a thickening of the transversalis fascia running deep and parallel to the inguinal ligament. It attaches to the superomedial part of the pubic bone medially, but laterally its fibres fan out within the fascia transversalis and fascia iliaca without bony attachment to the iliac spines. In contrast to the inguinal ligament, the histological analysis of the iliopubic tract shows a high elastin to collagen ratio. The functional significance of this structure merits further study, but there is no doubt that it is important in many approaches to inguinal herniorraphy. For this reason it is considered that the iliopubic tract deserves greater emphasis in the anatomy teaching of the inguinal region.

An ultrastructural study of the phagocytic activity of astrocytes in adult rat brain.

The role of adult astrocytes in the removal of cell debris and foreign particles following injury to the brain is controversial. This study was undertaken to elucidate the response of adult astrocytes to needle injury of the rat cerebral cortex, using a suspension of colloidal carbon as a marker for phagocytosis. Either a single or 2 successive injections of colloidal carbon suspension were made into the cerebral cortex. The animals were allowed to survive for periods of from 1 to 30 d. Unequivocal involvement of astrocytes in the removal of carbon particles was evident only in those brains which had been subjected to 2 successive injections of carbon. The particles were located in membrane-bound vacuoles and were subsequently sequestered in lysosomes. Carbon-containing astrocytes were observed in the immediate vicinity of the lesion, in the adjacent parenchyma, around blood vessels and abutting carbon-containing macrophages. This study demonstrates that adult astrocytes are involved in phagocytosis, but only as a second line of defence. The possible significance of carbon-laden astrocytes further away from the site of the lesion is discussed.

The histological and the histopathological pattern of conjunctival rhinosporidiosis associated with papillomavirus infection.

The present study describes for the first time, the clinical, light and electron microscopic findings of two cases of conjunctival rhinosporidiosis. One was with concurrent infection of papillomavirus. Investigations at the ultrastructural level have provided additional information on the development of Rhinosporidium seeberi and would suggest that the formation of the wall of this organism is a continuous morphological and biochemical spectrum throughout its cytological maturation. The current observation on the wall formation is probably a modification of the classical pattern as an environmental protection carried out by the fungus against the virus. In contradistinction to the usual histopathological picture of rhinosporidiosis, the case with the viral infection lacked the characteristic marked inflammatory reaction. This finding, together with the relatively short interval of the frequent recurrences of this lesion, have led us to postulate the presence of a localised acquired immune deficiency state. It is possible that this local immune deficiency may be caused by an immunosuppression mechanism. This is probably mediated by papillomavirus and/or due to the weak antigenicity of the host virus-infected cells which contain only copies of viral DNA in an unintegrated form.

Ultrastructural study of phagocytic activities of young astrocytes in injured neonatal rat brain following intracerebral injection of colloidal carbon.

The cellular reaction to injury in the mature central nervous system (CNS) has been extensively studied in both man and animals, while a detailed study of the reaction of the immature CNS to injury is lacking in the literature. This study was undertaken to elucidate the response of young astrocytes following injection injury to developing brain. Colloidal carbon was applied because it is a suitable marker for phagocytosis, it is nontoxic, and it is readily identifiable by light and electron microscopy. The cerebral cortex of the neonatal rat was injected with 0.1 microliter of colloidal carbon solution. The animals were allowed to survive from 1 hour to 30 days postoperation. The brains were fixed by vascular perfusion and processed for light and electron microscopy. Carbon particles were ingested in membrane-bound vacuoles and sequestered in lysosomes of young astrocytes. Astrocytes, loaded with carbon particles, were identified after 4 days, and were seen in abundance between 10 to 21 days postoperation. Carbon-laden astrocytes were seen in the immediate vicinity of the site of the injection; in the surrounding, apparently normal, neuropil; and in the perivascular regions. This study demonstrates the ability of young astrocytes to engulf foreign particles injected into the developing brain. The presence of carbon particles in astrocytes located further away from the site of injection is discussed.

Rhinosporidium seeberi and papovavirus infection of the conjunctiva: a clinical and ultrastructural study.

The present study describes, for the first time, the clinical and the ultrastructural findings of a rare case presented with concurrent conjunctival infection of Rhinosporidium seeberi and a papovavirus. In contradistinction to previous reports, the present case lacked the characteristic granulomatous inflammatory reaction of rhinosporidiosis. This finding, together with the frequent recurrence of the lesion, led us to postulate the presence of a Local Acquired Immune Deficiency State (LAIDS). This Local AIDS may be caused by an immunosuppression mechanism which is probably mediated by papovavirus.

Ultrastructural study of enzymes in reactive astrocytes: clarification of astrocytic activity.

Enzymes in reactive of the cerebral cortex were examined at the ultrastructural level in an attempt to resolve some conflicting aspects of astrocytic activity. Correlations between morphological and enzyme changes after injury established that the apparent increase in oxidative enzyme activity was exclusively mitochondrial and not an artefactual reaction product resulting from anoxic cellular damage. Pronounced glucose-6-phosphatase activity within cisternae of an increased amount of the granular endoplasmic reticulum was related to increased glycogen. Further evidence from acid phosphatase activity indicated that astrocytes played a minimal role in phagocytosis.