Neurological Disorders Flashcards
Over a period of several days a 35-year-old man developed total paralysis of his body and most of his face. He could not swallow or speak. Horizontal eye movements were impaired but vertical eye movements and eye blinks were maintained. Communication via a code of eye movements showed that he remained mentally alert and that sensation over his whole body remained intact. A brainstem vascular lesion was suspected.
Which pathway has been affected?
Corticospinal and corticobulbar tracts projecting to spinal and brainstem motor neurones respectively.
Over a period of several days a 35-year-old man developed total paralysis of his body and most of his face. He could not swallow or speak. Horizontal eye movements were impaired but vertical eye movements and eye blinks were maintained. Communication via a code of eye movements showed that he remained mentally alert and that sensation over his whole body remained intact. A brainstem vascular lesion was suspected.
Why are vertical but not horizontal eye movements maintained?
The lesion must be below the level of the oculomotor nucleus (vertical eye movements spared) but above that of the abducens (lateral eye movements lost) and all lower motor nuclei.
The preserved “eyeblinks” are not true reflexes as the motor nucleus of the facial nerve is below the level of the lesion. They will be intermittent upward movements of the eyelid made by the oculomotor innervation of the levator palpebrae muscles.
Over a period of several days a 35-year-old man developed total paralysis of his body and most of his face. He could not swallow or speak. Horizontal eye movements were impaired but vertical eye movements and eye blinks were maintained. Communication via a code of eye movements showed that he remained mentally alert and that sensation over his whole body remained intact. A brainstem vascular lesion was suspected.
Where in the brainstem is the lesion?
Basal part of the upper pons (locked-in syndrome – mercifully rare)
Over a period of several days a 35-year-old man developed total paralysis of his body and most of his face. He could not swallow or speak. Horizontal eye movements were impaired but vertical eye movements and eye blinks were maintained. Communication via a code of eye movements showed that he remained mentally alert and that sensation over his whole body remained intact. A brainstem vascular lesion was suspected.
Why are sensation and consciousness not affected?
The lesion is confined to the ventral (anterior) part of the brainstem thus sparing the ascending sensory tracts and reticular formation which are more dorsally (posteriorly) located.
Over a period of several days a 35-year-old man developed total paralysis of his body and most of his face. He could not swallow or speak. Horizontal eye movements were impaired but vertical eye movements and eye blinks were maintained. Communication via a code of eye movements showed that he remained mentally alert and that sensation over his whole body remained intact. A brainstem vascular lesion was suspected.
Which artery is most likely to have been involved?
Thrombosis of the basilar artery leads to this isolated lesion.
The medulla is still supplied by branches of the vertebral arteries while the internal carotid arteries maintain the circle of Willis for supply of the forebrain and midbrain.
A 46-year-old woman presented with weakness of the muscles of the left side of her face, accompanied by reduced sensation in the same area. On examination she was found to have reduced hearing in the left ear. She thought the deafness had been present for several months and also admitted to occasional bouts of dizziness.
These symptoms are all caused by a single lesion – where?
In or near the left internal acoustic meatus.
A 46-year-old woman presented with weakness of the muscles of the left side of her face, accompanied by reduced sensation in the same area. On examination she was found to have reduced hearing in the left ear. She thought the deafness had been present for several months and also admitted to occasional bouts of dizziness.
What type of lesion is it?
An acoustic schwannoma (also called acoustic neurinoma or neurofibroma) - a benign tumour which develops slowly on the vestibular part of the VIII cranial nerve.
A 46-year-old woman presented with weakness of the muscles of the left side of her face, accompanied by reduced sensation in the same area. On examination she was found to have reduced hearing in the left ear. She thought the deafness had been present for several months and also admitted to occasional bouts of dizziness.
Explain the symptoms in terms of the structures involved.
The first signs are usually sensorineural deafness due to pressure on the auditory part of the nerve, accompanied or followed by tinnitus and/or vertigo.
As the tumour grows out into the posterior fossa, there may be impaired facial sensation (e.g. demonstrated by loss of the corneal reflex) due to distortion of cranial nerve V, and weakness of the facial muscles due to stretching of nerve VII.
A 46-year-old woman presented with weakness of the muscles of the left side of her face, accompanied by reduced sensation in the same area. On examination she was found to have reduced hearing in the left ear. She thought the deafness had been present for several months and also admitted to occasional bouts of dizziness.
How can the condition be treated? (acoustic schwannoma)
Removed surgically but there is usually residual deafness.
Monitoring the tumour – small tumours often just need to be monitored with regular MRI scans, and the treatments below are generally only recommended if scans show it’s getting bigger
Brain surgery – surgery to remove the tumour through a cut in the skull may be carried out under general anaesthetic if it’s large or getting bigger
Stereotactic radiosurgery – small tumours, or any pieces of a larger tumour that remain after surgery, may be treated with a precise beam of radiation to stop them getting any bigger
What is likely to happen if an acoustic schwannoma is left untreated?
Further growth of the tumour could put pressure on the cerebellum and brainstem, causing unilateral ataxia (poor muscle control) + signs of raised intracranial pressure.
What are the syndromes you need to know?
locked-in syndrome
Thrombosis of the basilar artery (idk if it counts as a syndrome…)
acoustic schwannoma (also called acoustic neurinoma or neurofibroma)
