Afferent and efferent connections of the medial, inferior and lateral vestibular nuclei in the cat and monkey

Attempts were made to determine the afferent and efferent connections of the medial (MVN), inferior (IVN) and lateral (LVN) vestibular nuclei (VN) in the cat and monkey using retrograde and anterograde axoplasmic transport technics. Injections of HRP and [3H]amino acids were made selectively into MVN, IVN and LVN and into: (1) MVN and IVN, (2) LVN and IVN and (3) all 4 VN. Contralateral afferents to MVN arise from (1) the nuclei prepositus (NPP) and intercalatus (NIC), (2) all parts of MVN and cell group 'y' and (3) parts of the superior vestibular nucleus (SVN), IVN and the fastigial nucleus (FN). Ipsilateral projections to MVN arise from: (1) a central band of the flocculus and the nodulus and uvula, (2) the interstitial nucleus of Cajal (INC), and (3) visceral nuclei of the oculomotor nuclear complex (OMC). Efferent projections of MVN are to: (1) the ipsilateral supraspinal nucleus (SSN), and (2) the contralateral central cervical nucleus (CCN), MVN, SVN, cell group 'y', the rostroventral region of LVN, the trochlear nucleus (TN) and the INC. Projections to the abducens nuclei (AN) and the OMC are bilateral. Some ascending fibers in the cat cross within the OMC. In the monkey fibers from MVN end in a central band of the ipsilateral flocculus. Afferents to IVN arise ipsilaterally from SVN, the nodulus, the uvula and the anterior lobe vermis. Contralateral afferents arise from: (1) parts of CCN, MVN, SVN, IVN and cell group 'y' and (2) the central third of the FN. IVN receives bilateral projections from the perihypoglossal nuclei (PH) and the visceral nuclei of the OMC. Efferents from IVN project: (1) ipsilaterally to nucleus beta of the inferior olive, (2) contralaterally to parts of MVN, SVN and cell group 'y' and (3) bilaterally to the paramedian reticular nuclei. No commissural fibers interconnect cell groups 'f' and 'x'. Ascending fibers from IVN terminate contralaterally in the TN and the OMC. In the monkey fibers from IVN terminate in the ipsilateral nodulus, uvula and anterior lobe vermis; no fibers project to FN in either the cat or the monkey. Afferents to the LVN arise primarily from the ipsilateral anterior lobe vermis and bilaterally from rostral parts of the FN. No commissural fibers interconnect the LVN. Projections of the LVN are primarily to spinal cord via the vestibulospinal tract (VST); collaterals of the VST terminate in the lateral reticular nucleus (LRN). Ascending uncrossed projections from LVN in the cat terminate in the medial rectus subdivision of the OMC.(ABSTRACT TRUNCATED AT 400 WORDS)     

Evidence for wide range of time scales in oculomotor plant dynamics: implications for models of eye-movement control

Oculomotor-plant dynamics are not well characterised, despite their importance for modelling eye-movement control. We analysed the time course of the globe's return after horizontal displacements in three rhesus monkeys lightly anaesthetised with ketamine. The eye-position traces were well fitted by a sum of four exponentials (time constants 0.012, 0.099, 0.46, 7.8 s). The two long time-constant terms accounted for 25% of plant compliance, and led to a model that accounted for hitherto unexplained features of ocular motoneuron firing such as (i) hysteresis, and (ii) the inability of a 2 time-constant model to fit data for both fast and slow eye-movements.     

Ultrastructural organization of muscle fiber types and their distribution in the rat superior rectus extraocular muscle

Extraocular muscles (EOMs) are unique as they show greater variation in anatomical and physiological properties than any other skeletal muscles. To investigate the muscle fiber types and to understand better the structure-function correlation of the extraocular muscles, the present study examined the ultrastructural characteristics of the superior rectus muscle of rat. The superior rectus muscle is organized into two layers: a central global layer of mainly large-diameter fibers and an outer C-shaped orbital layer of principally small-diameter fibers. Six morphologically distinct fiber types were identified within the superior rectus muscle. Four muscle fiber types, three single innervated fibers (SIFs) and one multiple innervated fiber (MIF), were recognized in the global layer. The single innervated fibers included red, white and intermediate fibers. They differed from one another with respect to diameter, mitochondrial size and distribution, sarcoplasmic reticulum and myofibrillar size. The orbital layer contained two distinct MIFs in addition to the red and intermediate SIFs. The orbital MIFs were categorized into low oxidative and high oxidative types according to their mitochondrial content and distribution. The highly specialized function of the superior rectus extraocular muscle is reflected in the multiplicity of its fiber types, which exhibit unique structural features. The unique ultrastructural features of the extraocular muscles and their possible relation to muscle function are discussed.     

布比卡因在斜视治疗中应用的研究进展

布比卡因是长效酰胺类钠通道阻滞剂,除麻醉作用外,肌注后还能导致局部骨骼肌细胞变性、坏死、再生,使肌肉增粗、肌力增强,有研究者提出可以利用这一特性治疗斜视.目前,已有研究者对以共同性水平斜视为主的患者进行试治疗,大多数患者的眼位得到不同程度的改善,同时,亦有学者在病理学、分子生物学及细胞生物学等方面对布比卡因的作用机制进行研究.本文将对布比卡因在斜视领域的试用现状及可能的作用机制进行综述,以探讨未来的研究方向.     

Extraocular retinoblastoma in Indian children:clinical, imaging and histopathological features

AIM: To study eyes with extraocular dissemination (EORB), with the following aims:first to establish the mean lag period and to understand various reasons for delayed presentation, second to study their imaging profiles and third to analyze histopathological features of eyes enucleated after neoadjuvant chemotherapy.METHODS: Prospective study of clinical and imaging features of EORBs (stage Ⅲ and Ⅳ International Retinoblastoma Staging System) presenting to a tertiary eye care centre. Histopathological features of eyes enucleated after receiving neoadjuvant chemotherapy were analyzed. A pictorial illustration of the varied imaging profile of EORB was also presented.RESULTS: Over a period of one year, 97 eyes were diagnosed with retinoblastoma; 32 children (36 eyes) (37.1%) had EORB. Mean age 3.6±1.9 years, 71.9% males, 71.9% unilateral, 3.1% with positive family history and 40.6% with metastasis. On imaging, there was extrascleral involvement in 22.2%, involvement of orbital part of optic nerve in 33.3%, involvement of central nervous system in 27.8% and orbital wall involvement in 2.9% eyes. On histopathological analysis of eyes enucleated after neoadjuvant chemotherapy, 25.0% had no residual viable tumour tissue and rest all tumours were poorly differentiated.CONCLUSION:There are very few human malignancies where definitive treatment is started without any confirmed histopathological diagnosis and imaging plays an important role in diagnosis and appropriate staging of the disease. Chemotherapy has a variable effect on EORB, 75.0% of eyes with EORB had residual viable tumour tissue when enucleated after receiving neoadjuvant chemotherapy.     

Botulinum toxin as adjunct for refractory compressive optic neuropathy in Graves' disease

An euthyroid patient was referred for compressive optic neuropathy in Graves' disease. Under prednisone therapy the right and left visual acuities were 1.0 and 0.4, with a profound decrease in color vision on the left. Bilateral anterior orbital decompressions were performed. When prednisone was withdrawn postoperatively, the visual acuity of the right eye dropped to 0.32 with bilateral complete failure on the Ishihara color test. A biopsy of the inferior oblique muscle of the left eye confirmed Graves' disease and additional transantral decompression of the right orbital apex was performed. Under intravenous methylprednisolone therapy, the visual acuity dropped postoperatively to 0.2 and 0.4, respectively. 15 U botulinum toxin were given by retrobulbar injection between the inferior and lateral rectus muscles. Four days later the patient called and said that the visual acuity in the right eye had improved tremendously. Two weeks after the injection the visual acuity was 0.7 in both eyes, although prednisone had been reduced to 20 mg by that time. The convergent strabismus had increased but the already severely restricted motility of the right eye had been little affected by the retrobulbar injection, and adduction not at all. Orbital CT-scan showed thinning of the inferior and lateral rectus muscles, but not of the medial rectus.     

Complete ophthalmoplegia in Ipilmumab and Nivolumab combination treatment for metastatic melanoma

Ipilimumab and Nivolumab are novel monoclonal antibodies that have recently been used successfully for treatment of metastatic melanoma. Ipilimumab is a human monoclonal antibody against Cytotoxic T Lymphocyte Antigen 4 (CTLA4) receptor, which suppresses T-cell proliferation and stimulates an inflammatory response against cancer cells. Nivolumab is an IgG4 monoclonal antibody against the cytotoxic T lymphocyte associated programmed death 1 receptor (PD-1). Ipilimumab and Nivolumab combination treatment has been shown to induce remission and prolong survival in patients with metastatic melanoma. The side effect profile of these medications has not been well studied. One entity of the side effects reported in the literature is immune-related adverse events (irAEs). There have been few case reports where these events were serious and irreversible. In this case report, we describe a fatal and severe diffuse panmyositis that involved the cardiac, respiratory, and extraocular muscles in a patient with metastatic melanoma secondary to combination treatment with Ipilimumab/Nivolumab.     

银杏叶提取物金纳多治疗外伤性眼外肌麻痹

目的 观察银杏叶提取物金纳多对外伤性眼外肌麻痹的治疗效果.方法 68例（74眼）外伤性眼外肌麻痹分为两组,观察组应用金纳多注射液治疗,对照组给予传统的营养神经药物治疗,观察症状、体征改善的情况,比较两组的疗效.结果 观察组治愈率和有效率均明显高于对照组（x2=14.51,9.86,P＜0.05）.结论 应用金纳多注射液治疗外伤性眼外肌麻痹,提高了治愈率.     

Motion sickness is linked to nystagmus-related trigeminal brain stem input: a new hypothesis

Motion sickness is a common and distressing but poorly understood syndrome associated with nausea/vomiting and autonomic nervous system accompaniments that develops in the air or space as well as on sea or land. A bidirectional aetiologic link prevails between migraine and motion-sickness. Motion sickness provokes jerk nystagmus induced by both optokinetic and vestibular stimulation. Fixation of gaze or closure of eyes generally prevents motion sickness while vestibular otolithic function is eliminated in microgravity of space, indicating a predominant pathogenetic role for visuo-sensory input. Scopolamine, dimenhydrinate, and promethazine reduce motion-related nystagmus. Contraction of extraocular muscles generates proprioceptive neural traffic and can provoke an ocular hypertensive response. It is proposed that repetitive contractions of the extraocular muscles during motion-related jerk nystagmus rapidly augment brain stem afferent input by increasing proprioceptive neural traffic through connections of the oculomotor nerves with the ophthalmic nerve in the lateral wall of the cavernous sinus as well as by raising the intraocular pressure thereby stimulating anterior segment ocular trigeminal nerve fibers. This verifiable hypothesis defines the pathophysiological basis of individual susceptibility to motion sickness, elucidates the preventive mechanism of gaze fixation or ocular closure, advances the aetiologic link between MS and migraine, rationalizes the mechanism of known preventive drugs, and explores new therapeutic possibilities.