Neoplastic nerve lesions.

Though metastasis and malignant infiltration of the peripheral nervous system is relatively rare, physicians should have a familiarity with their presentations to allow for prompt diagnosis and initiation of treatment. This article will review the clinical presentations, diagnostic evaluation, and treatment of neoplastic involvement of the cranial nerves, nerve roots, peripheral nerves, and muscle. Due to the proximity of the neural structure traversing the skull base, metastasis to this region results in distinctive syndromes, most often associated with breast, lung, and prostate cancer. Metastatic involvement of the nerve roots is uncommon, apart from leptomeningeal carcinomatosis and bony metastasis with resultant nerve root damage, and is characterized by significant pain, weakness, and numbness of an extremity. Neoplasms may metastasize or infiltrate the brachial and lumbosacral plexuses resulting in progressive and painful sensory and motor deficits. Differentiating neoplastic involvement from radiation-induced injury is of paramount importance as it dictates treatment and prognosis. Neurolymphomatosis, due to malignant lymphocytic infiltration of the cranial nerves, nerve roots, plexuses, and peripheral nerves, deserves special attention given its myriad presentations, often mimicking acquired demyelinating neuropathies.

The Changing Nature of the Oncology Section of the Orthopaedic In-Training Examination.

INTRODUCTION: The Orthopaedic In-Training Examination (OITE) assesses orthopaedic resident knowledge over 275 multiple-choice questions.Since the first publication examining the contents of the pathology section was published over ten years ago, the pathology content has been renamed (oncology) and revamped. As the overall extent of these alterations is currently unknown, the efficacy of current orthopaedic oncology educational practices for optimal OITE performance should be questioned. To determine how the oncology (pathology) material has changed, we compared the following characteristics from previous examinations (2002 to 2006) to current examinations (2012 to 2016): (1) What are the average number of oncology questions being asked? (2) What are the specific imaging modalities presented for examinee interpretation? (3) Which pathologic diagnoses are commonly examined? (4) What is the pattern of taxonomic question classifications? METHODS: The 2012 to 2016 OITE study guides were reviewed, and each oncology question was categorized into one of the following: benign or malignant, imaging modality grouping, common pathologic diagnosis, question type, and taxonomic classification. The aforementioned information was extrapolated from the previous pathology publication published in 2010 to create the previous examination cohort (2002 to 2006). The current examination characteristics were then compared with those of the previous examinations. RESULTS: The current number of oncology OITE questions significantly decreased from previous years (27.2 versus 21.2; P = 0.015). Current examinations displayed a significant increase in testing the interpretation of diagnostic imaging modalities compared with previous examinations (78.3% versus 55.8%; P < 0.001). The current examinations examined a wide spectrum of pathologic diagnoses, including previously untested pathologies. The number of taxonomy 1 questions on current examinations significantly decreased (36.8% versus 24.5%; P = 0.032), whereas the number of taxonomy 3 questions significantly increased from previous examinations (48.1% versus 32.4%; P = 0.032). DISCUSSION: This study demonstrated that the nature of the orthopaedic oncology (pathology) section has changed over the past 10 years. Although the overall number of pathology-related questions decreased, the difficulty level of these questions increased, demanding a higher level of knowledge and critical thinking. A formal orthopaedic oncology rotation may be the best method to educate and improve OITE oncology performance. LEVEL OF EVIDENCE: Prognostic study, level III.

A differential cargo-loading model of ciliary length regulation by IFT.

BACKGROUND: During the assembly and maintenance of cilia, precursor proteins need to be transported from the cell body into the organelle. Intraflagellar transport (IFT) is assumed to be the predominant protein transport pathway in cilia, but it remains largely unknown how ciliary proteins use IFT to reach their destination sites in the cilium and whether the amount of cargo transported by IFT is regulated. RESULTS: Single-particle imaging showed that DRC4, a structural protein of the axoneme, moves in association with IFT particles inside Chlamydomonas reinhardtii cilia. IFT is required for DRC4 transport both into and within the cilium. DRC4 cargoes dissociate from IFT trains at the tip as well as at various sites along the length of the cilium. Unloaded DRC4 diffuses before docking at its axonemal assembly site. In growing cilia, DRC4 transport by IFT was strongly increased over the steady-state level, and the frequency decreased linearly with the increasing ciliary length. The frequency of DRC4 transport was similarly elevated in short growth-arrested cilia and remained high even when the amount of DRC4 available in the cell body was reduced. CONCLUSIONS: DRC4 is a bona fide cargo of IFT. Incompletely assembled cilia trigger an increase in the amount of DRC4 cargo transported by IFT particles, and DRC4 transport is downregulated as cilia approach their steady-state length. We propose a model in which ciliary length is controlled by regulating the amount of cargo transported by IFT particles.