Takayoshi Shimohata

Objective: To clarify the clinical features and risk factors of cervicogenic headache (CEH; as diagnosed according to the International Classification of Headache Disorders‐Third Edition beta) in patients with cervical spine disorders requiring surgery. Background: CEH is caused by cervical spine disorders. The pathogenic mechanism of CEH is hypothesized to involve a convergence of the upper cervical afferents from the C1, C2, and C3 spinal nerves and the trigeminal afferents in the trigeminocervical nucleus of the upper cervical cord. According to this hypothesis, functional convergence of the upper cervical and trigeminal sensory pathways allows the bidirectional (afferent and efferent) referral of pain to the occipital, frontal, temporal, and/or orbital regions. Previous prospective studies have reported an 86‐88% prevalence of headache in patients with cervical myelopathy or radiculopathy requiring anterior cervical surgery; however, these studies did not diagnose headache according to the International Classification of Headache Disorders criteria. Therefore, a better understanding of the prevalence rate, clinical features, risk factors, and treatment responsiveness of CEH in patients with cervical spine disorders requiring surgery is necessary. Methods: We performed a single hospital‐based prospective cross‐sectional study and enrolled 70 consecutive patients with cervical spine disorders such as cervical spondylotic myelopathy, ossification of the posterior longitudinal ligament, cervical spondylotic radiculopathy, and cervical spondylotic myeloradiculopathy who had been scheduled to undergo anterior cervical fusion or dorsal cervical laminoplasty between June 2014 and December 2015. Headache was diagnosed preoperatively according to the International Classification of Headache Disorders‐Third Edition beta. The Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire, Neck Disability Index, and a 0‐100 mm visual analog scale (VAS) were used to evaluate clinical features, and scores were compared between baseline (ie, preoperatively) and 3, 6, and 12 months post‐surgery. Results: The prevalence of CEH in our population was 15/70 (21.4%, 95%CI: 11.8% to 31.0%). The main clinical features were dull and tightening/pressing headache sensations in the occipital region. Headache severity was mild (VAS, 32 ± 11 mm) and only one patient reported use of an oral analgesic. Compared to patients without CEH, patients with CEH had higher frequencies of neck pain (86.7% vs. 50.9%; P = .017), cervical range of motion limitation (ROM) (66.7% vs. 38.2%; P = .049), and higher Neck Disability Index scores (14 vs. 3; P < .001). Among the different cervical spine disorders, the prevalence of CEH was highest in cervical spondylotic myeloradiculopathy patients (60%), being ≤ 20% for all other disorders. Surgical treatments including cervical laminoplasty to relieve abnormal pressure on the spinal cord via a posterior approach, were associated with initial improvements in headache VAS that slightly diminished by 12 months post‐surgery ( P < .001). Conclusions: We report a lower prevalence of CEH in patients with cervical spinal disorders requiring surgery than that reported previously. The main clinical features of CEH were mild, dull, and tightening/pressing headache sensations in the occipital region. Potential risk factors for CEH included neck pain, limited cervical ROM, high Neck Disability Index score, and a diagnosis of cervical spondylotic myeloradiculopathy. The further accumulation of patients in a multi‐institutional study may be required in order to discuss the diagnostic criteria and pathophysiology of this condition.

Cell-therapies that invoke pleiotropic mechanisms may facilitate functional recovery in stroke patients. We hypothesized that a cell therapy using microglia preconditioned by optimal oxygen-glucose deprivation (OGD) is a therapeutic strategy for ischemic stroke because optimal ischemia induces anti-inflammatory M2 microglia. We first delineated changes in angiogenesis and axonal outgrowth in the ischemic cortex using rats. We found that slight angiogenesis without axonal outgrowth were activated at the border area within the ischemic core from 7 to 14 days after ischemia. Next, we demonstrated that administration of primary microglia preconditioned by 18 hours of OGD at 7 days prompted functional recovery at 28 days after focal cerebral ischemia compared to control therapies by marked secretion of remodelling factors such as vascular endothelial growth factor, matrix metalloproteinase-9, and transforming growth factor-β polarized to M2 microgliain vitro/vivo. In conclusion, intravascular administration of M2 microglia preconditioned by optimal OGD may be a novel therapeutic strategy against ischemic stroke.

Clinical manifestations of methylmercury (MeHg) intoxication include cerebellar ataxia, concentric constriction of visual fields, and sensory and auditory disturbances. The symptoms depend on the site of MeHg damage, such as the cerebellum and occipital lobes. However, the underlying mechanism of MeHg-induced tissue vulnerability remains to be elucidated. In the present study, we used a rat model of subacute MeHg intoxication to investigate possible MeHg-induced blood-brain barrier (BBB) damage. The model was established by exposing the rats to 20-ppm MeHg for up to 4 weeks; the rats exhibited severe cerebellar pathological changes, although there were no significant differences in mercury content among the different brain regions. BBB damage in the cerebellum after MeHg exposure was confirmed based on extravasation of endogenous immunoglobulin G (IgG) and decreased expression of rat endothelial cell antigen-1. Furthermore, expression of vascular endothelial growth factor (VEGF), a potent angiogenic growth factor, increased markedly in the cerebellum and mildly in the occipital lobe following MeHg exposure. VEGF expression was detected mainly in astrocytes of the BBB. Intravenous administration of anti-VEGF neutralizing antibody mildly reduced the rate of hind-limb crossing signs observed in MeHg-exposed rats. In conclusion, we demonstrated for the first time that MeHg induces BBB damage via upregulation of VEGF expression at the BBB in vivo. Further studies are required in order to determine whether treatment targeted at VEGF can ameliorate MeHg-induced toxicity.

This review focuses on the mechanisms and emerging concepts of stroke and therapeutic strategies for attenuating hemorrhagic transformation (HT) after tissue plasminogen activator (tPA) treatment for acute ischemic stroke (AIS). The therapeutic time window for tPA treatment has been extended. However, the patients who are eligible for tPA treatment are still ＜5% of all patients with AIS. The risk of serious or fatal symptomatic hemorrhage increases with delayed initiation of treatment. HT is thought to be caused by 1) ischemia/reperfusion injury; 2) the toxicity of tPA itself; 3) inflammation; and/or 4) remodeling factor-mediated effects. Modulation of these pathophysiologies is the basis of direct therapeutic strategies to attenuate HT after tPA treatment. Several studies have revealed that matrix metalloproteinases and free radicals are potential therapeutic targets. In addition, we have demonstrated that the inhibition of the vascular endothelial growth factor-signaling pathway and supplemental treatment with a recombinant angiopoietin-1 protein might be a promising therapeutic strategy for attenuating HT after tPA treatment through vascular protection. Moreover, single-target therapies could be insufficient for attenuating HT after tPA treatment and improving the therapeutic outcome of patients with AIS. We recently identified progranulin, which is a growth factor and a novel target molecule with multiple therapeutic effects. Progranulin might be a therapeutic target that protects the brain through suppression of vascular remodeling (vascular protection), neuroinflammation, and/or neuronal death (neuroprotection). Clinical trials which evaluate the effects of anti-VEGF drugs or PGRN-based treatment with tPA will be might worthwhile.

The prevalence of esophageal involvement and its impact on clinical manifestations in patients with multiple system atrophy (MSA) remains unknown. We recruited 16 consecutive patients with dysphagia associated with MSA (MSA group) and 16 consecutive patients with dysphagia associated with amyotrophic lateral sclerosis (ALS group). We assessed the presence or absence of food stagnation within the esophagus using videofluorography. Food stagnation within the esophagus was observed in 16 patients (100 %; 7 severe, 9 mild) in the MSA group and in 4 patients (25 %; 4 mild) in the ALS group (P < 0.001). Follow-up videofluorography revealed that food stagnation in patients with MSA could exacerbate during the disease course. Patients with MSA and severe food stagnation showed a wide range of intraesophageal stasis by videofluorography. Among the 16 patients in the MSA group, 4 developed aspiration pneumonia and 1 died of suffocation associated with food regurgitation during continuous positive airway pressure therapy. In conclusion, food stagnation within the esophagus occurs more frequently in MSA patients with dysphagia than in ALS patients with dysphagia. Because food stagnation can cause serious complications such as aspiration pneumonia and suffocation, patients with MSA should be evaluated by videofluorography, especially those with stagnation in the esophageal phase.

Hypoglycemic encephalopathy (HE) is caused by a lack of glucose availability to neuronal cells, and no neuroprotective drugs have been developed as yet. Studies on the pathogenesis of HE and the development of new neuroprotective drugs have been conducted using animal models such as the hypoglycemic coma model and non-coma hypoglycemia model. However, both models have inherent problems, and establishment of animal models that mimic clinical situations is desirable. In this study, we first developed a short-term hypoglycemic coma model in which rats could be maintained in an isoelectric electroencephalogram (EEG) state for 2 min and subsequent hyperglycemia without requiring anti-seizure drugs and an artificial ventilation. This condition caused the production of 4-hydroxy-2-nonenal (4-HNE), a cytotoxic aldehyde, in neurons of the hippocampus and cerebral cortex, and a marked increase in neuronal death as evaluated by Fluoro-Jade B (FJB) staining. We also investigated whether N-(1,3-benzodioxole-5-ylmethyl)-2,6-dichlorobenzamide (Alda-1), a small-molecule agonist of aldehyde dehydrogenase-2, could attenuate 4-HNE levels and reduce hypoglycemic neuronal death. After confirming that EEG recordings remained isoelectric for 2 min, Alda-1 (8.5 mg/kg) or vehicle (dimethyl sulfoxide; DMSO) was administered intravenously with glucose to maintain a blood glucose level of 250 to 270 mg/dL. Fewer 4-HNE and FJB-positive cells were observed in the cerebral cortex of Alda-1-treated rats than in DMSO-treated rats 24 h after glucose administration (P = 0.002 and P = 0.020). Thus, activation of the ALDH2 pathway could be a molecular target for HE treatment, and Alda-1 is a potentially neuroprotective agent that exerts a beneficial effect on neurons when intravenously administered simultaneously with glucose.

In the central nervous system, progranulin, a glycoprotein growth factor, plays a crucial role in maintaining physiological functions, and progranulin gene mutations cause TAR DNA-binding protein-43-positive frontotemporal lobar degeneration. Although several studies have reported that progranulin plays a protective role against ischaemic brain injury, little is known about temporal changes in the expression level, cellular localization, and glycosylation status of progranulin after acute focal cerebral ischaemia. In addition, the precise mechanisms by which progranulin exerts protective effects on ischaemic brain injury remains unknown. Furthermore, the therapeutic potential of progranulin against acute focal cerebral ischaemia, including combination treatment with tissue plasminogen activator, remains to be elucidated. In the present study, we aimed to determine temporal changes in the expression and localization of progranulin after ischaemia as well as the therapeutic effects of progranulin on ischaemic brain injury using in vitro and in vivo models. First, we demonstrated a dynamic change in progranulin expression in ischaemic Sprague-Dawley rats, including increased levels of progranulin expression in microglia within the ischaemic core, and increased levels of progranulin expression in viable neurons as well as induction of progranulin expression in endothelial cells within the ischaemic penumbra. We also demonstrated that the fully glycosylated mature secretory isoform of progranulin (∼88 kDa) decreased, whereas the glycosylated immature isoform of progranulin (58–68 kDa) markedly increased at 24 h and 72 h after reperfusion. In vitro experiments using primary cells from C57BL/6 mice revealed that the glycosylated immature isoform was secreted only from the microglia. Second, we demonstrated that progranulin could protect against acute focal cerebral ischaemia by a variety of mechanisms including attenuation of blood–brain barrier disruption, neuroinflammation suppression, and neuroprotection. We found that progranulin could regulate vascular permeability via vascular endothelial growth factor, suppress neuroinflammation after ischaemia via anti-inflammatory interleukin 10 in the microglia, and render neuroprotection in part by inhibition of cytoplasmic redistribution of TAR DNA-binding protein-43 as demonstrated in progranulin knockout mice (C57BL/6 background). Finally, we demonstrated the therapeutic potential of progranulin against acute focal cerebral ischaemia using a rat autologous thrombo-embolic model with delayed tissue plasminogen activator treatment. Intravenously administered recombinant progranulin reduced cerebral infarct and oedema, suppressed haemorrhagic transformation, and improved motor outcomes (P = 0.007, 0.038, 0.007 and 0.004, respectively). In conclusion, progranulin may be a novel therapeutic target that provides vascular protection, anti-neuroinflammation, and neuroprotection related in part to vascular endothelial growth factor, interleukin 10, and TAR DNA-binding protein-43, respectively.