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Autonomic Disorders in Parkinsonism
Published in M.D. Francesco Amenta, Peripheral Dopamine Pathophysiology, 2019
Wade L. Collier, Francesco Amenta
Martignoni and associates9 used an infrared TV pupillometer to monitor the pupillary responses to various types of ocular stimuli in both untreated and treated Parkinsonian patients.10 They were especially interested in studying direct and consensual light reflexes, near vision reaction, and pupil response to acoustic stimuli. They discovered that untreated patients, after adjusting for light adaptation, had a greater pupil diameter when compared to controls of the same age. Parkinsonian patients had light reflexes which were reduced in amplitude contraction and which required only one half the redilatation time when compared to the controls. Moreover, latency was normal in direct light reflex. This strongly suggests that there is an alteration of the central integrative mechanisms of pupil reactivity.11 Martignoni’s group did not observe an amplitude reduction of near vision response, which is frequent in Parkinsonian patients who are treated with anticholinergic drugs. They found that l-dopa therapy changed pupil responsiveness, causing an increased resting pupil size, and a reduction in the latency, contraction amplitude, and the half-redilatation time of the light reflex. Loewenfield and Rosskothen12 attribute these findings to an overactive sympathetic nervous system, due to a high inhibitory firing of the parasympathetic oculomotor nerve complex.
Neurologic care
Published in Hemanshu Prabhakar, Charu Mahajan, Indu Kapoor, Essentials of Anesthesia for Neurotrauma, 2018
Maria Chiara Casadio, Paola Cristina Volpi, Giuseppe Citerio
The first and most fundamental component of patient evaluation is the clinical neurologic examination. It should include assessing the level of consciousness by using the GCS1 or the Full Outline of UnResponsiveness (FOUR) score,12 which provides additional information on brainstem reflexes and respiratory drive. Pupil size and pupillary light reflex should be assessed with an automated pupilometer, which provides greater accuracy than a clinical pupil examination.13
Brain death and ethical issues: Death by neurological criteria
Published in Hemanshu Prabhakar, Charu Mahajan, Indu Kapoor, Essentials of Geriatric Neuroanesthesia, 2019
Brittany Bolduc, David M. Greer
After confirming a comatose state, the physician can move on to cranial nerve testing. All cranial nerve reflexes must be absent for the diagnosis of brain death. Pupillary response to a bright light must be absent in both eyes. The pupils are typically fixed in mid-position (4–9 mm) due to sympathetic and parasympathetic denervation (4). Pinpoint pupils should alert the provider to possible drug effect. A magnifying glass or pupilometer may be used to detect small changes in pupil size. In a patient with proper spinal integrity, oculocephalic reflexes should be tested by rapidly turning the patient's head from side to side and vertically with the eyes held open. There should be no eye movement in the brain-dead patient. Vestibuloocular reflexes should be tested using maximal ice water caloric stimulation. First, otoscopic examination is performed to ensure that tympanic membrane is intact and external auditory canals are patent. The head of the bed should be at 30°. Fifty mL of ice water is infused into one ear through a flexible, dull-ended tube, such as a butterfly catheter with the needle removed. The infusion occurs over 1 minute, while an assistant holds open the patient's eyes. A patient who is brain dead will display no response to this test, including no grimace, eye movements, or motor response. An interval of 5 minutes should exist before testing the other ear (17). The corneal reflex should be tested with a cotton swab applicator pressed carefully on the cornea bilaterally. Facial muscle response to noxious stimuli should be assessed by applying deep pressure to the temporomandibular joint and the supraorbital ridge. No grimace should be seen. Gag and cough reflexes can be tested by suctioning the patient's endotracheal tube or by stimulating the posterior pharynx with a tongue depressor. A jaw jerk reflex should be absent. Again, all cranial nerve reflexes must be absent bilaterally in order to diagnose brain death and to proceed with further testing.
Dilation velocity is associated with Glasgow Coma Scale scores in patients with brain injury
Published in Brain Injury, 2021
Barsha Thakur, Hend Nadim, Folefac Atem, Sonja E. Stutzman, DaiWai M. Olson
Apart from GCS, the pupillary examination is an important neurological assessment method. It is a noninvasive procedure where the response of the pupil to the direct light is recorded (10). Normally, the pupil reacts spontaneously to light. Delayed response or sluggish response could be an indication of increased intracranial pressure (ICP) and/or severe head injury (10). Methods for assessing PLR have evolved with time, from traditional methods using natural light or flashlights which are subjective and prone to inaccuracy (11,12) to the pupillometer. The pupillometer is an automated handheld device that can detect subtle changes in pupil size, constriction velocity, dilation velocity, latency and the Neurological Pupil Index™ (NPi) (13). The NPi is a calculation that compares a patient’s pupil measurements to a healthy model derived from healthy volunteers (14). NPi is graded on a scale of 0–5 where ≥3 or more is considered normal response, and < 3 indicates an abnormal PLR response. The NPI method of assessing pupil reactivity provides a high level accuracy and high inter-rater reliability (15), eliminating subjective assessments.
Contrast Acuity and the King-Devick Test in Huntington’s Disease
Published in Neuro-Ophthalmology, 2020
Ali G. Hamedani, Tanya Bardakjian, Laura J. Balcer, Pedro Gonzalez-Alegre
Pupillometry was performed using a NeurOptics PLR-300 pupillometer (NeurOptics, Irvine, CA), a handheld, monocular, infrared video pupillometer.19 After two minutes of dark adaptation, pupillary diameter was recorded continuously for five seconds following a brief (31 millisecond) flash of white light (180 uW) in each eye. Encouragement to maintain eye opening during the five seconds of recording was provided, but if the recording was interrupted by blinks, the test was repeated. The pupillometer provides automatic detection of pupillary diameter and calculation of maximum diameter (mm), minimum diameter (mm), percent change in pupillary diameter, constriction latency (mm/s), average constriction velocity (mm/s), maximum constriction velocity (mm/s), average dilation velocity (mm/s), and time to 75% recovery of pupillary diameter(s).
Optical pupillometry in traumatic brain injury: neurological pupil index and its relationship with intracranial pressure through significant event analysis
Published in Brain Injury, 2019
A. R. Stevens, Z. Su, E. Toman, A. Belli, D. Davies
An objective, reproducible alternative for pupillary assessment is the optical pupillometer. This is a handheld “point-and-shoot” device comprising of a camera, light and processor which measures pupillary responses to light. This device measures seven parameters of the pupillary light reflex and culminates these algorithmically into a “neurological pupil index” (NPi), displaying to the operator a scalar value of pupillary response between 0 and 5. A lower score is indicative of impaired pupillary activity, with a score of less than 3 deemed “abnormal” (4,5). This method of gauging pupil reactivity has the advantage of minimal inter-observer variability, less vulnerability to environmental factors such as ambient light, and the ability to detect subtle changes not observable through manual methods (6,7).