Biomedical subjects

Timothy Saunders

Publications and source records attributed to Timothy Saunders.

3 recordsLinked to original sources

PubMed2006

Emergency department sonographic measurement of optic nerve sheath diameter to detect findings of increased intracranial pressure in adult head injury patients.

STUDY OBJECTIVE: Our objective is to determine whether a bedside ultrasonographic measurement of optic nerve sheath diameter can accurately predict the computed tomographic (CT) findings of elevated intracranial pressure in adult head injury patients in the emergency department (ED). METHODS: We conducted a prospective, blinded observational study on adult ED patients with suspected intracranial injury with possible elevated intracranial pressure. Exclusion criteria were age younger than 18 years or obvious ocular trauma. Using a 7.5-MHz ultrasonographic probe on the closed eyelids, a single optic nerve sheath diameter was measured 3 mm behind the globe in each eye. A mean binocular optic nerve sheath diameter greater than 5.00 mm was considered abnormal. Cranial CT findings of shift, edema, or effacement suggestive of elevated intracranial pressure were used to evaluate optic nerve sheath diameter accuracy. RESULTS: Fifty-nine patients were enrolled in the study. Average age was 38 years, and median Glasgow Coma Scale score was 15 (interquartile 6 to 15). Eight patients with an optic nerve sheath diameter of 5.00 mm or more had CT findings that correlated with elevated intracranial pressure. The sensitivity for the ultrasonography in detecting elevated intracranial pressure was 100% (95% confidence interval [CI] 68% to 100%) and specificity was 63% (95% CI 50% to 76%). The sensitivity of ultrasonography for detection of any traumatic intracranial injury found by CT was 84% (95% CI 60% to 97%) and specificity was 73% (95% CI 59% to 86%). CONCLUSION: Bedside ED optic nerve sheath diameter ultrasonography has potential as a sensitive screening test for elevated intracranial pressure in adult head injury.

Adult↗

PubMed2005

Optic nerve sheath diameter does not change with patient position.

OBJECTIVES: Optic nerve sheath diameter (ONSD) has been proposed as a marker for increased intracranial pressure. Trendelenburg's position is often used in hypotensive patients and reverse Trendelenburg's position (30 degrees head up) is often used in head injury patients. We asked if there would be any change in OSND in healthy human adults between the supine, Trendelenburg's, and reverse Trendelenburg's positions. METHODS: Prospective case-control blinded study using consenting healthy adults. Three separate investigators measured the ONSD in each eye of 10 separate volunteers in the supine, Trendelenburg's, and reverse Trendelenburg's positions with 30 degrees angulation from the horizontal. Data were analyzed using the paired t test. RESULTS: In the supine position, the mean ONSD was 4.6 +/- 0.71 (SD) mm in the right eye and 4.5 +/- 0.56 (SD) mm in the left eye. In Trendelenburg's position, the mean ONSD was 4.4 +/- 0.72 (SD) mm in the right eye and 4.7 +/- 0.53 (SD) mm in the left eye. In reverse Trendelenburg's position, the mean ONSD was 4.4 +/- 0.49 (SD) mm in the right eye and 4.8 +/- 0.76 (SD) mm in the left eye. There was no significant difference in OSND between positions for either eye by analysis of variance. Interobserver agreement was +/-1 mm in at least 90% of the subjects regardless of position. CONCLUSION: Optic nerve sheath diameter measurement by ultrasound does not significantly change with Trendelenburg's or reverse Trendelenburg's position in comparison with the supine position in healthy individuals.

Adult↗

PubMed2005

Posttraumatic abducens to oculomotor nerve misdirection.

INTRODUCTION: Paradoxical patterns of extraocular muscle, eyelid, or pupillary movements can occur following injury between divisions of the oculomotor nerve, trigeminal and abducens nerves, and trigeminal and oculomotor nerves. We report three cases of unusual ocular motility and eyelid movements that are a result of aberrant connections between the abducens and oculomotor nerves. METHODS: Three patients with unusual eye movement abnormalities after trauma were studied. A complete ophthalmic examination plus neuroradiologic evaluation were performed. RESULTS: Each patient manifested an aberrant connection between the 6th and 3rd cranial nerves resulting in third nerve function during sixth nerve stimulation. Two patients demonstrated complete third nerve palsies except for adduction on attempted abduction. The third showed improved bilateral ptosis on abduction. CONCLUSIONS: The neuroanatomical abnormalities involve intraorbital structures in one patient and central nervous system pathways in the others. Explanations such as retrograde regeneration, ephaptic transmission, or denervation supersensitivity do not appear to explain these unusual eye movements. The most likely mechanism involves some form of peripheral neuronal misdirection. These rare sixth to third nerve misdirection cases add support to the "neuronal misdirection hypothesis" of aberrant eye movements after trauma.

Abducens Nerve↗