Tracy, Jennifer A.

ABSTRACT The glutamic acid decarboxylase 65‐kilodalton isoform (GAD65) antibody is a biomarker of autoimmune central nervous system (CNS) disorders and, more commonly, nonneurological autoimmune diseases. Type 1 diabetes, autoimmune thyroid disease, and pernicious anemia are the most frequent GAD65 autoimmune associations. One or more of these disorders coexists in approximately 70% of patients with GAD65 neurological autoimmunity. Neurological phenotypes have CNS localization and include limbic encephalitis, epilepsy, cerebellar ataxia, and stiff‐person syndrome (SPS), among others. Classic SPS is a disorder on the spectrum of CNS hyperexcitability which also includes phenotypes that are either more restricted (stiff‐limb syndrome) or more widespread (progressive encephalomyelitis with rigidity and myoclonus). GAD65 antibody is not highly predictive of a paraneoplastic cause for neurological disorders, but diverse cancer types have been occasionally reported. For all phenotypes, responses to immunotherapy are variable (approximately 50% improve). GAD65 autoimmunity is important to recognize for both coexisting nonneurological autoimmune associations and potential immunotherapy‐response. Muscle Nerve 56 : 15–27, 2017

ABSTRACTIntroductionNeurolymphomatosis (NL) is a rare disorder characterized by invasion of cranial or peripheral nerves, nerve roots, or plexi, usually by aggressive subtypes of non‐Hodgkin lymphoma (NHL). The most common clinical presentation is that of a painful polyneuropathy or polyradiculopathy, followed by cranial neuropathy and, less frequently, by painless polyneuropathy.MethodsClinical and pathologic findings are reported for 2 NL cases.ResultsThe following 2 patients with NL, with disparate clinical presentations, are presented: a patient with subacute onset, painful, multifocal, mixed axonal and demyelinating radiculoplexus neuropathy due to a large B‐cell NHL, who required 2 targeted fascicular nerve biopsies to demonstrate NL; and a patient with a slowly progressive, length‐dependent axonal polyneuropathy due to a low‐grade B‐cell lymphoproliferative disorder, as shown on a diagnostic sural nerve biopsy.ConclusionsThe cases described illustrate the wide clinical spectrum of NL. Muscle Nerve 52:449–454, 2015

Perineural tumor spread in prostate cancer is emerging as a mechanism to explain select cases of neurological dysfunction and as a cause of morbidity and tumor recurrence. Perineural spread has been shown to extend from the prostate bed to the lumbosacral plexus and then distally to the sciatic nerve or proximally to the sacral and lumbar nerves and even intradurally. The authors present a case of a bilateral neoplastic lumbosacral plexopathy that can be explained anatomically as an extension of the same process: from one lumbosacral plexus to the contralateral one utilizing the dural sac as a bridge between the opposite sacral nerve roots. Their theory is supported by sequential progression of symptoms and findings on clinical examinations as well as high-resolution imaging (MRI and PET/CT scans). The neoplastic nature of the process was confirmed by a sciatic nerve fascicular biopsy. The authors believe that transmedian dural spread allows continuity of a neoplastic process from one side of the body to the other.

ABSTRACTIntroduction: A 24‐year‐old man with primary hyperoxaluria type 1 (PH1) presented with a rapidly progressive axonal and demyelinating sensorimotor polyradiculoneuropathy shortly after the onset of end‐stage renal disease. His plasma oxalate level was markedly elevated at 107 µmol/L (normal <1.8 µmol/L). Methods: A sural nerve biopsy was performed. Teased fiber and paraffin and epoxy sections were done and morphometric procedures were performed on this sample and on an archived sample from a 22‐year‐old man as an age‐ and gender‐matched control. Embedded teased fiber electron microscopy was also performed. Results: The biopsy revealed secondary demyelination and axonal degeneration. Under polarized light, multiple bright hexagonal, rectangular, and starburst inclusions, typical of calcium oxalate monohydrate crystals, were seen. Conclusions: The proposed mechanisms of nerve damage include disruption of axonal transport due to crystal deposition, toxic effect of oxalate, or nerve ischemia related to vessel occlusion from oxalate crystal deposition. Muscle Nerve 51: 449–454, 2015