Brainstem Lesions Part 2

Question 1

Describe Wallenberg syndrome/lateral medullary syndrome/Syndrome of posterior inferior cerebellar artery (PICA)

Answer 1

Destruction of spinal lemniscus results in contralateral hemianalgesia
Destruction of descending tract of V results in ipsilateral loss of pain and temperature from face
Destruction of glossopharyngeal and vagus nerves
Destruction of nucleus ambiguus
Destruction of solitary nucleus results in ipsilateral loss of visceral sensations and reflexes from palate and pharynx; ipsilateral loss of taste sensations from 1/2 of tongue and pharynx
Destruction of spinocerebellar tracts may result in asynergia or hypotonia
Irritation of vestibular nuclei may result in nystagmus

Question 2

Describe cerebellopontine angle (CPA) syndrome

Answer 2

One of most common tumors of posterior cranial fossa in adults in acoustic neurinoma. As tumor enlarges, it compresses lateral aspect of pons, cerebellum, and medulla
Destruction of vestibulocochlear nerve results in deafness and vestibular disturbances
Destruction of facial nerve results in Bell’s palsy
Destruction of descending tract of V results in ipsilateral loss of pain/temperature sensations from face
Destruction of spinal lemniscus results in contralateral hemianalgesia of body
Involvement of cerebellar peduncles results in some degree of ipsilateral cerebellar ataxia, intention tremor, dysmetria, and dysdiadochokinesia

Question 3

Describe Benedikt’s syndrome (lesion of midbrain tegmentum)

Answer 3

Destruction of oculomotor nerve results in external strabismus, pupillary dilation, and complete ptosis
Destruction of medial lemniscus results in contralateral loss of proprioception and 2pt tactile discrimination from body and limbs
Lesions of red nucleus, fibers of superior cerebellar peduncle, and midbrain tegmentum present with ipsilateral oculomotor palsy, and contralateral motor dysfunction such as tremor, ataxia, or choreiform movements. Patients may also show varying degrees of spasticity

Question 4

Describe Parinaud’s syndrome

Answer 4

Due to lesion of superior colliculus which contains a center for controlling upward gaze
Principal sign is paralysis of upward gaze
May be due to pineal tumor or varix of great vein of Galen
These lesions may also destroy posterior commissure and a concomitant loss of consensual light reflex

Question 5

Describe thalamic syndrome (Dejerine=Roussy syndrome)

Answer 5

Usually due to thrombosis of posterior choroidal or thalamogeniculate branches of posterior cerebral arteries
State of constant spontaneous pain without appropriate external stimulus; diffuse
Modification of emotional control: exhibit extreme mood swings from laughter to sobbing within short periods of time
May also involve contralateral hemihypalgesia (crawling ant sensations), hemiparesis, homonymous hemianopia, or auditory deficits

Question 6

Describe lesions of nucleus ambiguus and spinal lemniscus

Answer 6

Destruction of nucleus ambiguus results in dysphagia, dyarthria, hoarseness, paresis of ipsilateral palatal muscles
Destruction of spinal lemniscus results in contralateral loss of pain and temperautre
Lesions may extend medially to include medial lemniscus (contralateral proprioceptive and 2pt tactile hemianesthesia of body) and solitary nucleus (ipsilateral anesthesia of palate and pharynx and loss of taste sensations from 1/2 of tongue and pharynx (gag reflex))