lesion II

Question 1

What cranial nerves and tracts are closely located to midline of pons

Answer 1

• TRACTS

–> pyramidal tract

–> medial lemniscus

CRANIAL NERVES (level of lesion is localized by CN)

–> OCULOMOTOR (CNIII) = UPPER alternating hemiplegia

–> ABDUCENT (CN VI) = MIDDLE alternating hemiplegia

–> HYPOGLOSSAL (CN XII) = LOWER alternating hemiplegia

Question 2

define alternating hemiplegia

Answer 2

• includes syndrome in which

–> CRANIAL NERVE MOTOR deficits are exhibited on ONE SIDE

WHEREAS

–> DESCENDING LONG MOTOR TRACT deficits are exhibited on the OPPOSITE SIDE

Question 3

What tracts are located laterally

Answer 3

• Spinothalamic tract
• spinal tract of V

Question 4

What cranial nerves located laterally

Answer 4

• Trigeminal (CN V) = midpons
• Facial (CN VII) = caudal pons
• Vestibulocochlear (CN VIII) = caudal pons, medulla
• Glossopharyngeal (CN IX) = medulla
• Vagus (CN X) = medulla

*Horner’s syndrome = IPSILATERAL TO LESION

*CEREBELLAR SIGNS = ATAXIA, ipsilateral to lesion

Question 5

Describe Dysarthria hemiparesis (pure motor hemiparesis) syndrome

Answer 5

• CAUSED BY Basilar artery (PARAMEDIAN BRANCHES)
• Structures affected:

–> CORTICONUCLEAR tract (UMN) = CONTRALATERAL lower face weakness and DYSARTHRIA

–> CORTICOSPINAL tract (UMN) = deficits in CONTRALATERAL upper and lower limb weakness

Question 6

Define Dysarthria

Answer 6

• Motor speech disorder due to weakness/paralysis of the mouth (lips, tongue and lower face)

Question 7

Describe ataxic Hemiparesis Syndrome

Answer 7

• Caused by occlusion in PARAMEDIAN BRANCHES (ventral territory of the pons)

–> CORTICONUCLEAR tracts (UMN) = CONTRALTERAL lower face weakness and DYSARTHRIA

–> CORTICOSPINAL tract (UMN) = CONTRALATERAL upper and lower limb weakness (motor hemiparesis)

–> PONTINE NUCLEI/PONTOCEREBELLAR FIBERS = CONTRALATERAL ATAXIA

Question 8

Describe FOVILLE’S SYNDROME

Answer 8

• Occluded PARAMEDIAN BRANCHES (ventral and dorsal territories of pons)
• CORTICONUCLEAR tract = CONTRALATERAL lower face weakness and DYSARTHRIA
• CORTICOSPINAL tract = CONTRALATERAL upper and lower weakness
• FACIAL COLLICULUS (LMN)

–> abducen nucleus/paramedian pontine reticular formation (PPRF) = ipsilateral horizontal (lateral) gaze paralysis

–> facial nerve root fascicles = IPSILATERAL face paralysis

Question 9

Pontine Wrong-way Eyes syndrome

Answer 9

• Caused by OCCLUDED Paramedian branches (supply ventral and dorsal territories of pons
• STRUCTURES AFFECTED

–> Corticonuclear tract = Dysarthria and CONTRALATERAL lower face weakness

–> corticospinal tract = CONTRALATERAL upper and lower limb weakness

• Abducens nucleus or Paramedian pontine reticular formation (PPRF) = IPSILATERAL lateral gaze paralysis

Question 10

Millard-Gubler syndrome

Answer 10

• Caused by Paramedian branch occlusion
• STRUCTURE

–> corticonuclear tract = CONTRALATERAL lower face weakness and dysarthria

–> Corticospinal tract = CONTRALATERAL upper and lower limb weakness

–> Facial nerve fascicles (LMN) = IPSILATERAL facial weakness

Question 11

What regions are variably invovled in Lesion in Medial Pontine basis and tegmentum

Answer 11

• Caused by occlusion of paramedian branches
• STRUCTURES
• -> Medial lemniscus = CONTRALATERAL decreased proprioception, vibratory sense and tactile discrimination

–> Medial longitudinal fasciculus (MLF) = internuclear ophthalmoplegia (INO)

Question 12

describe the lesion of the lateral caudal pons (AICA syndrome)

Answer 12

• caused by AICA occluded

–> Middle cerebellar peduncle = IPSILATERAL ataxia

–> Vestibular nuclei = vertigo and nystagmus

–> Trigeminal nucleus/tract = IPSILATERAL facial decreased pain and thermal sense

–> spinothalamic tract = CONTRALATERAL body decreased pain and thermal sense

–> Descending sympathetic fibers = IPSILATERAL horner’s syndrome

Question 13

describe lesion in DORSOLATERAL rostral pons (superior cerebellar artery syndrome)

Answer 13

• Caused by occlusion in superior cerebellar artery
• SUPERIOR cerebellar peduncle and cerebellum = IPSILATERAL ataxia and cerebellar origin

Question 14

Medial medullary syndrome

Answer 14

• Lesion in medial medulla caused by occlusions of anterior spinal artery (paramedian branches) or vertebral artery (paramedian branches)
• structures affected (infarction)

–> corticospinal tract = weakness in CONTRALATERAL upper and lower limbs (contralateral hemiparesis)

–> hypoglossal nerve and nucleus (LMN) = weakness/paralysis of the IPSILATERAL tongue and ATROPHY of the IPSILATERAL tongue muscles

–> Medial lemniscus = CONTRALATERAL decreased vibratory and proprioceptive sensation and discriminatory (fine) touch sensation

Question 15

Describe the cause Lateral medullary syndrome (WALLENBERG syndrome)

Answer 15

• Lesion in Lateral medulla
• Caused by vertebral artery (thombosis) or PICA (thrombosis)

Question 16

What structuers are affected in Wallenberg’s syndrome (lateral medullary syndrome)

Answer 16

• Inferior cerebellar peduncle = Ipsialteral ataxia
• vestibular nuclei = unsteady gait, vertigo, nausea, vomiting
• spinothalamic tract = decrease/loss of pain and thermal sense from CONTRALATERAL side
• spinal tract/nucleus of V = decrease/loss of pain and thermal sense from IPSILATERAL face
• Descending sympathetic fibers = ISPILATERAL Horner’s syndrome
• nucleus ambiguus = dysphonia, dysphagia, ispilateral decrease of gag reflex
• nucleus solitarius = decrease in taste sensation IPSILATERAL tongue
• Loss of vertical orientation = perceives world as it is upside down or turned sideways