Faculty Bibliography

We report four patients with monocular visual loss for whom optical coherence tomography (OCT) was helpful in distinguishing the sequelae of retinal artery occlusion from those of primary optic neuropathy. Determinations of the peripapillary retinal nerve fiber layer (RNFL) thickness as well as macular retinal layer thicknesses and architecture were used. The major findings in our patients show that changes in the inner retinal layers (including ganglion cell and inner plexiform layer) with disruption of normal macular architecture supports a diagnosis of retinal artery occlusion. Our results support the use of OCT imaging for patients with monocular visual loss of uncertain etiology; macular imaging as well as peripapillary RNFL thickness measurement can be helpful in differentiating primary retinal disease or ischemia from primary disorders of the optic nerve.

OBJECTIVE: Concussion is a major public health problem and considerable efforts are focused on sideline-based diagnostic testing to guide return-to-play decision-making and clinical care. The King-Devick (K-D) test, a sensitive sideline performance measure for concussion detection, reveals slowed reading times in acutely concussed subjects, as compared to healthy controls; however, the normal behavior of eye movements during the task and deficits underlying the slowing have not been defined. METHODS: Twelve healthy control subjects underwent quantitative eye tracking during digitized K-D testing. RESULTS: The total K-D reading time was 51.24 (+/-9.7) seconds. A total of 145 saccades (+/-15) per subject were generated, with average peak velocity 299.5 degrees /s and average amplitude 8.2 degrees . The average inter-saccadic interval was 248.4ms. Task-specific horizontal and oblique saccades per subject numbered, respectively, 102 (+/-10) and 17 (+/-4). Subjects with the fewest saccades tended to blink more, resulting in a larger amount of missing data; whereas, subjects with the most saccades tended to make extra saccades during line transitions. CONCLUSIONS: Establishment of normal and objective ocular motor behavior during the K-D test is a critical first step towards defining the range of deficits underlying abnormal testing in concussion. Further, it sets the groundwork for exploration of K-D correlations with cognitive dysfunction and saccadic paradigms that may reflect specific neuroanatomic deficits in the concussed brain.

Mild head injury such as concussions and subconcussive repetitive impact may lead to subtle changes in brain function and it is imperative to find sensitive and reliable tests to detect such changes. Tests involving the visual system, in particular eye movements, can incorporate higher cortical functioning and involve diffuse pathways in the brain, including many areas susceptible to head impact. With concussions, the clinical neuro-ophthalmic exam is important for detecting abnormalities in vergence, saccades, pursuit, and visual fixation. On the sidelines, the King-Devick test has been used as a visual performance measure that incorporates eye movements and increases the sensitivity in detecting possible concussions in conjunction with standard sideline tests of cognition, symptom checklists, and balance. Much promise lies in the eye movement laboratory to quantitate changes in saccades and pursuit with concussions using video-oculography. A combination of eye movement tasks coupled with neuroimaging techniques and other objective biomarkers may lead to a better understanding of the anatomical and physiological consequences of concussion and to better understand the natural history of this condition.

PURPOSE OF REVIEW: Idiopathic intracranial hypertension (IIH) is a potentially blinding disorder of unknown cause, characterized by elevated intracranial pressure in the absence of a mass lesion, venous sinus thrombosis, or meningitis. This review summarizes recent developments and insights from leading treatment trials, emerging treatment options, and evolving ways to evaluate IIH. RECENT FINDINGS: The Idiopathic Intracranial Hypertension Treatment Trial is the first large-scale, randomized, prospective study to evaluate medical treatment of patients with mild vision loss. These data have facilitated our understanding of baseline clinical manifestations, including impact on quality of life and treatment outcomes. Recent hypotheses and studies evaluating the role of cerebral venous sinus stenosis and stenting are discussed. Technological advances in optical coherence tomography are emerging to provide novel ways of evaluating and tracking optic disc swelling in IIH. SUMMARY: Recent changes in defining IIH, understanding the impact and treatment of mild visual loss, and the roles that cerebral venous stenting and optical coherence tomography might have in clinical practice provide the framework to better treat patients with IIH.

This paper proposes a parametric model for saccadic waveforms. The model has a small number of parameters, yet it effectively simulates a variety of physiologic saccade properties. In particular, the model reproduces the established relationship between peak saccadic angular velocity and saccadic amplitude (i.e., the saccadic main sequence). The proposed saccadic waveform model can be used in the evaluation and validation of methods for quantitative saccade analysis. For example, we use the proposed saccade model to evaluate four well-known saccade detection algorithms. The comparison indicates the most reliable algorithm is one by Nystrom et al. We further use the proposed saccade model to evaluate the standard technique used for the estimation of peak saccadic angular velocity. The evaluation shows the occurrence of systematic errors. We thus suggest that saccadic angular velocity values determined by the standard technique (low-pass differentiation) should be interpreted and used with caution.

Objective: Progressive ataxia with palatal tremor (PAPT) is a rare clinical syndrome characterized by progressive imbalance, dysarthria and visual disturbances. Neuroimaging typically demonstrates hypertrophy and T2 hyperintensity of the olivary complexes. To date, only a few cases of sporadic PAPT have been reported in the literature. Here, we present a patient with idiopathic, degenerative progressive cerebellar ataxia with palatal tremor. Methods: An 80-year-old male presented with two-year history of slowly progressive truncal ataxia, incoordination, dysarthria, dysphagia and visual disturbances. The patient had no history of stroke, demyelinating disease, autonomic dysfunction or other movement disorders. There was no significant family history. Results: Neurological examination was significant for dysarthric speech, dysmetria on finger-nose-finer test, dysdiadochokinesis, axial ataxia, mild bradykinesia, subtle hypermetric saccades and palatal myoclonus 2 Hz, (without an audible click). There was no nystagmus. Paraneoplastic antibodies, including GAD-65, were not present. MRI showed bilateral, symmetric hypertrophy and T2/FLAIR hyperintensity in the inferior olivary nuclei. Conclusion: Sporadic PAPT may be more common than previously thought. Careful clinical examination (including observation of the soft palate for myoclonic movements) may help to reveal the diagnosis. This presentation should be included in the differential diagnosis of hypertrophic olivary degeneration secondary to vascular or demyelinating lesion within the triangle of Guillain-Mollaret

Although primary dystonia is defined by its characteristic motor manifestations, non-motor signs and symptoms have increasingly been recognized in this disorder. Recent neuroimaging studies have related the motor features of primary dystonia to connectivity changes in cerebello-thalamo-cortical pathways. It is not known, however, whether the non-motor manifestations of the disorder are associated with similar circuit abnormalities. To explore this possibility, we used functional magnetic resonance imaging to study primary dystonia and healthy volunteer subjects while they performed a motion perception task in which elliptical target trajectories were visually tracked on a computer screen. Prior functional magnetic resonance imaging studies of healthy subjects performing this task have revealed selective activation of motor regions during the perception of 'natural' versus 'unnatural' motion (defined respectively as trajectories with kinematic properties that either comply with or violate the two-thirds power law of motion). Several regions with significant connectivity changes in primary dystonia were situated in proximity to normal motion perception pathways, suggesting that abnormalities of these circuits may also be present in this disorder. To determine whether activation responses to natural versus unnatural motion in primary dystonia differ from normal, we used functional magnetic resonance imaging to study 10 DYT1 dystonia and 10 healthy control subjects at rest and during the perception of 'natural' and 'unnatural' motion. Both groups exhibited significant activation changes across perceptual conditions in the cerebellum, pons, and subthalamic nucleus. The two groups differed, however, in their responses to 'natural' versus 'unnatural' motion in these regions. In healthy subjects, regional activation was greater during the perception of natural (versus unnatural) motion (P < 0.05). By contrast, in DYT1 dystonia subjects, activation was relatively greater during the perception of unnatural (versus natural) motion (P < 0.01). To explore the microstructural basis for these functional changes, the regions with significant interaction effects (i.e. those with group differences in activation across perceptual conditions) were used as seeds for tractographic analysis of diffusion tensor imaging scans acquired in the same subjects. Fibre pathways specifically connecting each of the significant functional magnetic resonance imaging clusters to the cerebellum were reconstructed. Of the various reconstructed pathways that were analysed, the ponto-cerebellar projection alone differed between groups, with reduced fibre integrity in dystonia (P < 0.001). In aggregate, the findings suggest that the normal pattern of brain activation in response to motion perception is disrupted in DYT1 dystonia. Thus, it is unlikely that the circuit changes that underlie this disorder are limited to primary sensorimotor pathways.

Introduction Pituitary neoplasms are benign entities that require distinct diagnostic and treatment considerations. Recent advances in endoscopic transsphenoidal surgery have resulted in shorter lengths of stay (LOS). We implemented a postoperative day (POD) 1 discharge paradigm involving a multidisciplinary approach and detailed preoperative evaluation and review of both medical and socioeconomic factors. Methods The experience of a single neurosurgeon/ears, nose, throat (ENT) team was reviewed, generating a preliminary retrospective database of the first 30 patients who underwent resection of pituitary lesions under the POD 1 discharge paradigm. We assessed multiple axes from their preoperative, in-house, and postoperative care. Results There were 14 men and 16 women with an average age of 53.8 years (range: 27-76 years). There were 22 nonsecretory and 8 secretory tumors with average size of 2.80 cm (range: 1.3-5.0 cm). All 30 patients underwent preoperative ENT evaluation. Average LOS was 1.5 +/- 0.7 days. A total of 18 of 30 patients were discharged on POD 1. The insurance status included 15 with public insurance such as emergency Medicaid and 15 with private insurance. Four patients had transient diabetes insipidus (DI); none had permanent DI. Overall, 28 of 30 patients received postoperative steroids. Factors that contributed to LOS > 1 day included public insurance status, two or more medical comorbidities, diabetes mellitus, transient panhypopituitarism, and DI. Conclusion The implementation of a POD 1 discharge plan for pituitary tumors is feasible and safe for elective patients. This implementation requires the establishment of a dedicated Pituitary Center model with experienced team members. The consistent limitation to early discharge was socioeconomic status. Efforts that incorporate the analysis of social disposition parameters with proper management of clinical sequelae are crucial to the maintenance of ideal LOS and optimal patient outcomes.