Convergence-retraction nystagmus (eyes make convergent and retracting oscillations following an upward saccade)
Jackson syndrome. It’s paralysis of structures innervated by the tenth, eleventh, and twelfth cranial nerves, including the soft palate, larynx, half of the tongue, and the sternomastoid and trapezius muscles.
It’s caused by occlusion of the vertebral artery. Its signs are:
Paralysis of the soft palate and vocal cords on one side which cause dysphagia and dysphonia.
Loss of pain sensation and temperature sense on the other side.
Horner's syndrome may be associated.
Avellise syndrome. It usually results from occlusion of the vertebral artery. Its signs are:
Paralysis of the soft palate and vocal cords on one side which cause dysphagia and dysphonia.
Loss of pain sensation and temperature sense on the other side, including the extremities, trunk, and neck.
Horner's syndrome may be associated.
In the original description, the vagus and glossopharyngeal nerves were involved; concomitant involvement of the neighbouring cranial nerves was observed later.
Bulbar palsy is a syndrome of lower motor neuron paralysis, affecting muscles innervated by cranial nerves (mainly IX-XII) that have their nuclei closely approximated in the lower brain stem. Muscles of the face, palate, pharynx, larynx, sternocleidomastoid, upper trapezius, and tongue are usually affected. Patients may present clinically with dysarthria, dysphagia, hoarseness, nasal voice, palatal deviation, diminished gag reflex, or weakness of the sternocleidomastoid, upper trapezius, or tongue. The main causes are brain stem infarct, syringobulbia, glioma, poliomyelitis, encephalitis, and motor neuron disease (amyotrophic lateral sclerosis or progressive bulbar palsy), tumors, chronic meningitis, aneurysms, neck trauma, and congenital abnormalities (Chiari malformation or basilar impression).
Pseudobulbar palsy is a syndrome of upper motor neuron paralysis that affects the corticobulbar system above the brain stem bilaterally. Although it presents with most of the signs and symptoms of bulbar palsy, the causative lesion is not in the brain stem. This condition causes dysphagia, dysarthria, and paresis of the tongue (without atrophy or fasciculations). The reflex movements of the soft palate and pharynx are frequently hyperactive (incontrast to bulbar palsy). Frontal signs (grasp, snout, suck, and glabellar reflex) may be present. Emotional incontinence with exaggerated crying (or, less often, laughing) is also common and may be due to disruption of frontal efferents subserving emotional expression. The main causes are multiple lacunar infarcts or chronic ischemia in the hemispheres. Other causes are ALS and multiple sclerosis.
The examination of comatose patients with brainstem dysfunction include next items:
Mental status
Breathing
Pupillary size and light response
Spontaneous eye movement or deviation
Oculocephalic reflex on head turning (doll's eye movement)
Oculovestibular test of gaze response to ice-water calorics
Motor response to supraorbital nerve pressure (noxious stimulus)
Presence of other brain stem reflexes (corneal, gag, and ciliospinal)
Brain death is a clinical diagnosis of cessation of all cerebral and brain stem function. Its signs are:
All brain stem reflexes (corneal, pupillary, gag, ciliospinal) are absent.
The pupils are midposition or large and fixed.
Oculocephalic and oculovestibular reflexes are absent.
Muscle tone is flaccid, with no spontaneous facial movement and no motor response to stimuli.
This condition should be present for 6-24 hours in adults. Metabolic causes (hypothermia, hypotension) and drug effects (neuromuscular blockers, sedative drugs) need to be ruled out.