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Biomedical subjects

J Frisby

Publications and source records attributed to J Frisby.

6 recordsLinked to original sources
PubMed2003

Depth cue reliance in surgeons and medical students.

BACKGROUND: Depth perception is reduced in endoscopic surgery, although little is known about the effect this has on surgical performance. METHODS: To assess the role of depth cues, 45 subjects completed tests of depth cue reliance. Surgical skill was assessed using the Minimally Invasive Surgical Trainer-Virtual Reality, a previously validated laparoscopic simulator. RESULTS: We could demonstrate no difference in cue reliance for three depth cues--namely stereo, texture, and outline--between surgeons and medical students. Greater dominance on stereo for medical students was a positive finding and a negative finding for the surgeons when correlated with surgical performance. CONCLUSIONS: We suggest that surgeons learn to adapt to the nonstereo environment in MIS, and this is the first study to show evidence of this phenomenon. This difference in stereo reliance is a reflection of the experience that surgeons have with laparoscopy compared with medical students, who have none.

Adult↗
PubMed2002

Swallowing outcomes following laryngectomy and pharyngolaryngectomy.

OBJECTIVES: To determine the incidence of dysphagia (defined as the inability to manage a diet of normal consistencies) at hospital discharge and beyond 1 year postsurgery and examine the impact of persistent dysphagia on levels of disability, handicap, and well-being in patients. DESIGN: Retrospective review and patient contact. SETTING: Adult acute care tertiary hospital. PATIENTS: The study group, consecutively sampled from January 1993 to December 1997, comprised 55 patients who underwent total laryngectomy and 37 patients who underwent pharyngolaryngectomy with free jejunal reconstruction. Follow-up with 36 of 55 laryngectomy and 14 of 37 pharyngolaryngectomy patients was conducted 1 to 6 years postsurgery. MAIN OUTCOME MEASURES: Number of days until the resumption of oral intake; swallowing complications prior to and following discharge; types of diets managed at discharge and follow-up; and ratings of disability, handicap, and distress levels related to swallowing. RESULTS: Fifty four (98%) of the laryngectomy and 37 (100%) of the pharyngolaryngectomy patients experienced dysphagia at discharge. By approximately 3 years postsurgery, 21 (58%) of the laryngectomy and 7 (50%) of the pharyngolaryngectomy patients managed a normal diet. Pharyngolaryngectomy patients experienced increased duration of nasogastric feeding, time to resume oral intake, and incidence of early complications affecting swallowing. Patients experiencing long-term dysphagia identified significantly increased levels of disability, handicap, and distress. Patients without dysphagia also experienced slight levels of handicap and distress resulting from taste changes and increased durations required to complete meals of normal consistency. CONCLUSIONS: The true incidence of patients experiencing a compromise in swallowing following surgery has been underestimated. The significant impact of impaired swallowing on a patient's level of perceived disability, handicap, and distress highlights the importance of providing optimal management of this negative consequence of surgery to maximize the patient's quality of life.

Adult↗
PubMed2001

Brain stem compression by a giant vertebrobasilar aneurysm mimicking seronegative myasthenia.

A patient is described with a vertebrobasilar aneurysm who was erroneously thought to have myasthenia gravis on the basis of the clinical presentation and investigations, which were interpreted as supportive of a disorder of the neuromuscular junction. Despite the correct diagnosis being made at a late stage the patient made a full recovery after radiological intervention.

Adult↗
PubMed1999

The 'ecological' probability density function for linear optic flow: implications for neurophysiology.

A theoretical analysis of the recovery of shape from optic flow highlights the importance of the deformation components; however, pure deforming stimuli elicit few responses from flow-sensitive neurons in the medial superior temporal (MST) area of the cerebral cortex. This finding has prompted the conclusion that MST cells are not involved in shape recovery. However, this conclusion may be unjustified in view of the emerging consensus that MST cells perform nonlinear pattern matching, rather than linear projection as implicitly assumed in many neurophysiological studies. Artificial neural models suggest that the input probability density function (PDF) is crucial in determining the distribution of responses shown by pattern-matching cells. This paper therefore describes a Monte-Carlo study of the joint PDF for linear optic-flow components produced by ego-motion in a simulated planar environment. The recent search for deformation-selective cells in MST is then used to illustrate the importance of the input PDF in determining cell characteristics. The results are consistent with the finding that MST cells exhibit a continuum of responses to translation, rotation, and divergence. In addition, there are negative correlations between the deformation and conformal components of optic flow. Consequently, if cells responsible for shape analysis are present in the MST area, they should respond best to combinations of deformation with other first-order flow components, rather than to the pure stimuli used in previous neurophysiological studies.

Eye Movements↗
PubMedDate not supplied

Differential modes of alaryngeal communication and long-term voice outcomes following pharyngolaryngectomy and laryngectomy.

Patterns of vocal rehabilitation for 37 pharyngolaryngectomy patients and 55 total laryngectomy patients over a 5-year period were compared. An electrolarynx (EL) was introduced as the initial communication mode immediately after surgery for 98% of patients, with 30% of pharyngolaryngectomy and 74% of laryngectomy patients subsequently developing tracheoesophageal speech (TES) as their primary mode of communication. Follow-up with 14 of 37 pharyngolaryngectomy patients and 36 of 55 laryngectomy patients was conducted 1-6 years following surgery and revealed that 90% of the pharyngolaryngectomy patients maintained the use of TES in the long term compared to 69% of the laryngectomy group. Long-term outcomes relating to communication disability and handicap did not differ significantly between the two surgical groups, however the laryngectomy patients had significantly higher levels of wellbeing. Across the whole group of patients, statistical comparison revealed that patients using TES had significantly lower levels of disability, handicap and distress than EL users. Considering that lower levels of disability, handicap and distress are associated with TES, and the data supports that suitably selected patients can maintain functional TES in the long term, increased application of this form of communication rehabilitation should be encouraged where viable for the pharyngolaryngectomy population.

Adult↗