Aberrant neuronal activity in injured peripheral nerves is believed to be an important factor in the development of neuropathic pain. Pharmacological blockade of that activity has been shown to mitigate the onset of associated molecular events in the nervous system. However, results in preventing onset of pain behaviors by providing prolonged nerve blockade have been mixed. Furthermore, the experimental techniques used to date to provide that blockade were limited in clinical potential in that they would require surgical implantation. To address these issues, we have used liposomes (SDLs) containing saxitoxin (STX), a site 1 sodium channel blocker, and the glucocorticoid agonist dexamethasone to provide nerve blocks lasting ∼1 wk from a single injection. This formulation is easily injected percutaneously. Animals undergoing spared nerve injury (SNI) developed mechanical allodynia in 1 wk; nerve blockade with a single dose of SDLs (duration of block 6.9 ± 1.2 d) delayed the onset of allodynia by 2 d. Treatment with three sequential SDL injections resulting in a nerve block duration of 18.1 ± 3.4 d delayed the onset of allodynia by 1 mo. This very prolonged blockade decreased activation of astrocytes in the lumbar dorsal horn of the spinal cord due to SNI. Changes in expression of injury-related genes due to SNI in the dorsal root ganglia were not affected by SDLs. These findings suggest that formulations of this kind, which could be easy to apply clinically, can mitigate the development of neuropathic pain.

Injectable materials often have shortcomings in mechanical and drug-eluting properties that are attributable to their high water contents. A water-free, liquid four-armed PEG modified with dopamine end groups is described which changed from liquid to elastic solid by reaction with a small volume of Fe3+ solution. The elastic modulus and degradation times increased with increasing Fe3+ concentrations. Both the free base and the water-soluble form of lidocaine could be dissolved in the PEG4-dopamine and released in a sustained manner from the cross-linked matrix. PEG4-dopamine was retained in the subcutaneous space in vivo for up to 3 weeks with minimal inflammation. This material’s tailorable mechanical properties, biocompatibility, ability to incorporate hydrophilic and hydrophobic drugs and release them slowly are desirable traits for drug delivery and other biomedical applications.

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Coadministration of S1SCBs with dexmedetomidine provided prolonged corneal anesthesia without delaying corneal wound healing. Such formulations may be useful for the management of acute surgical and nonsurgical corneal pain.

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Purpose: Subperiosteal orbital lesions are most commonly abscesses secondary to sinusitis but, in rare cases, may represent other processes. Here, the authors compare the clinical and radiographic presentation of subperiosteal abscesses and alternate subperiosteal processes (“masqueraders”) in an effort to establish distinguishing preoperative diagnostic criteria. Methods: A retrospective chart review of cases of subperiosteal orbital lesions that underwent surgical intervention over a 3-year period was performed. The medical records of 6 cases of subperiosteal masqueraders and 6 cases of abscesses were reviewed for the clinical course, imaging (including radiographic density of lesions), and pathology. Clinical and radiographic features of the 2 groups were compared. Results: All cases presented with orbital signs on exam. Fever and leukocytosis were absent in the masquerader group and present in 3 patients from the abscess group. Common radiographic findings in both groups included a rim-enhancing convex mass along the orbital wall and adjacent sinus opacification, often with bony dehiscence. Of the masqueraders, the final diagnosis was hematoma in 3 cases, mucocele in 1, and malignancy in 2. The difference between the mean radiodensity of the subperiosteal abscesses, 38 ± 5 Hounsfield units (95% CI, 34–42), as compared with the average radiodensity of the masqueraders, 71 ± 5 Hounsfield units (95% CI, 67–75), was significant (p = 0.042). Comparing radiodensity of the orbital lesion to adjacent sinus lesions and metastatic lesions elsewhere was also informative in establishing the diagnosis. Conclusions: Radiographic features, particularly radiodensity, may help distinguish subperiosteal abscesses from other lesions and aid in preoperative diagnosis and management.

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Purpose of review Orbital disease represents a diverse spectrum of pathology and can result in a variety of neuro-ophthalmic manifestations. The aim of this review is to provide updates on recent advances in our understanding of orbital disease secondary to thyroid eye disease, myositis, IgG4-related disease, sarcoidosis, granulomatosis with polyangiitis and various tumours. Recent findings With regards to thyroid eye disease, there have been recent advances in the development of steroid-sparing therapies, new modalities for objectively monitoring disease activity and increased understanding of the role of environmental risk factors. There has been interest in characterizing the clinical course and underlying mechanism of optic nerve disease secondary to orbital disorders, which has led to advances in how we monitor for and prevent permanent vision loss. Increased knowledge of orbital tumour subtype histopathology and the development of novel classification systems has had prognostic value and aided medical decision-making. Summary Orbital disease occurs secondary to a wide variety of diseases and can lead to neuro-ophthalmic manifestations with significant morbidity. Advances in our understanding of different subtypes of orbital disease have improved our ability to treat these potentially debilitating conditions.