Visual Field Loss and Visual Neglect

It has been estimated that 30-60% of individuals who sustain an acute stroke suffer from visual field loss due to partial or complete hemianopia. Neurological damage affecting the parietal or temporal lobes and involving the sensory pathway between the optic chiasma and visual cortex underlies this problem. The impact of loss in up to half the visual field is that food items on a meal tray may not be seen and therefore may remain uneaten. Compensatory interventions include instruction in scanning the visual field, or placing items within it for those who are unable to do this. Consistent placement of items on a meal tray and verbal identification of contents using a clock system is also helpful.

Neurological damage affecting the visual cortex of the occipital lobe, common following right hemisphere strokes, can result in neglect of half the visual space. A classic feature of this problem is failure to eat food on the left side of a plate. Affected individuals need reminding to focus on food items in the neglected space; placing a colored marker on one side of the plate can be helpful. This problem may occur in conjunction with visual field loss.

Table 1 Stages of swallowing: effects of stroke Stage

1. Oral preparation

Duration variable

Lip closure forms anterior seal

Comminution of food by mandibular, maxillary teeth; chewing of food Salivation evoked by parasympathetic nervous system Bolus formation controlled by tongue

Sensory feedback from oral mucosa on volume and consistency determine timing of bolus ejection

2. Oral transport Duration 1 s

Bolus of 5-15 cm-1 separated, moved to tongue midline Oral cavity sealed, mandible raised, pressure exerted by tongue against palate propels bolus to posterior oral cavity

3. Pharyngeal transport/reflex swallowing

Duration 0.5-0.6s

Bolus impacts on sensory receptors in tissues of soft palate, pharynx, tongue, fauces

Swallowing reflex stimulated; elevation/closure of velopharyngeal mechanism, elevation of larynx, closure of vocal cords, pharyngeal peristalsis, relaxation of esophageal sphincter

Respiration transiently ceases as bolus enters esophagus; breathing resumed; soft palate returned to resting position

4. Esophageal transport

Duration 8-20 s

Peristalsis moves bolus to stomach

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