brain stem pathology.pptx-hem

The medulla oblongata not only contains many cranial nerve nuclei that are concerned with vital functions (regulation of heart rate and respiration),but it also serves as a conduit for the passage of ascending and descending tracts connecting the spinal cord to the higher centers of the nervous system.

These tracts may become involved in demyelinatingdiseases, neoplasms, and vascular disorders.

(1) Medial medullary syndrome

occlusion of vertebral artery medullary branch .

Ipsilateral to lesion

Structures involved Signs and symptoms

CN XII,hypoglossal,or nucleus Paralysis with atrophy of half the tongue with deviation to the paralyzed side when tongue is protruded

Contralateral to lesion

Structures involved Signs and symptoms

Corticospinal tract Paralysis of UE and LE

Medial lemniscus Impaired tactile and proprioceptive sense

(2) Lateral medullary syndrome (wallenburg’s syndrome)

occlusion of any of five vessels may be responsible—vertebral, posterior inferior cerebellar, or superior, middle, or inferior lateral medullary arteriesIpsilateral to lesion

Structures involved Signs and symptoms

Descending tract and decreased pain and nucleus of CN V,Trigeminal temperature sensation in

face

Ceraballum or cerebellar ataxia: gait andinferior cerebellar peduncle limbs ataxia

Structures involved Signs and symptoms

Vestibular nuclei and connections vertigo, nausea, vomiting, nystagmus

Descending sympathetic tract Horner’s syndrome( miosis, ptosis, decreased sweating)

CN IX, Glossopharyngeal, and Dysphagia and dysphonia:CN X,vagus, or nuclei paralysis of palatal and laryngeal

muscles, diminished gag reflex

Cuneate and gracile nuclei sensory impairment of Ipsilateral UE,trunk,or LE

Contralateral to lesion

Structures involved Signs and symptoms

Spinal lemniscus-spinothalamic impaired pain and thermal tract sense over 50% of body,

sometimes face

The Pons situated in the posterior cranial fossa lying beneath the tentorium cerebelli. It is related anteriorly to the basilar artery, the dorsum sellae of the sphenoid bone, and the basilar part of the occipital bone.

In addition to forming the upper half of the floor of the fourth ventricle, it possesses several important cranial nerve nuclei(Trigeminal, Abducent , Facial and Vestibulocochlear )and serves as a conduit for important ascending and descending tracts ( Corticonuclear, Corticopontine , Corticospinal , Medial longitudinal fasciculus , and Medial , Spinaland lateral Lemnisci )therefore, that tumors, hemorrhage,or infarcts in this area of the brainstem produce a veriety of symptoms and signs.

(1)-MEDIAL INFERIOR PONTINE SYNDROME

Occlision of paramedian branch of basilar artery

Ipsilateral to lesion

Structures involved Signs and symptoms

Pontine center for lateral Paralysis of conjugate gaze togaze paramedian pentine side of lesion(preservation ofreticular formation(PPRF) convergence)

Vestibular nuclei and Nystagmusconnections

Structures involved Signs and symptoms

Middle cerebellar peduncle Ataxia of limbs and gait

CN VI(Abducens) or nucleus Diplopia on lateral gaze

Contralateral to lesion

Structures involved Signs and symptoms

Corticobulbar and corticospinal Paresis of face ,UE andtract in lower pons LE

Medial lemniscus Impaired tactile and proprioceptive sense over 50% of the body

(2)-LATERAL INFERIOR PONTINE SYNDROME

Occlusion of anterior inferior cerebellar artery, a branch of

the basilar artery.

Ipsilateral to lesion

Structures involved Signs and symptoms

CN VIII(Vestibular) or nucleus Horizontal and vertical nystagmus,vertigo,nausea, vomiting

CN VII(Facial )or nucleus Facial paralysis

Structures involved Signs and symptoms

Pontine center for lataral Paralysis of conjugategaze(PPRF) gaze to side of lesion

CN VIII(Cochlear )or nucleus Deafness,tinnitus

Middle cerebellar peduncle Ataxiaand cerebellar hemisphere

Main sensory nucleus and impaired sensation overdescending tract of fifth nerve face

Contralateral to lesion

Structures involved Signs and symptoms

Spinothalamic tract impaired pain and thermal sense over half the body

(3)-MEDIAL MIDPONTINE SYNDROME

Occlusion of paramedian branch of the mid-basilar artery

Ipsilateral to lesion

Structures involved Signs and symptoms

Middle cerebellar peduncle Ataxia of limbs and gait

Contralateral to lesion

Structures involved Signs and symptoms

Corticobulbar and corticospinal tract Paralysis of face,UE and LE

Pontine center of lateral gaze Deviation of eyes

(4)-LATERAL MIDPONTINE SYNDROME

Occlusion of short circumferential artery

Ipsilateral to lesion

Structures involved Signs and symptoms

Middle cerebellar peduncle Ataxia of limbs

Motor fibers or nucleus of Paralysis of muscles ofCN V(trigeminal) mastication

Sensory fibers or nucleus of Impaired sensation overCN V (trigeminal) side of face

(5)-MEDIAL SUPERIOR PONTINE SYNDROME

Occlusion of paramedian branches of upper basilar artery

Ipsilateral to lesion

Structures involved Signs and symptoms

Superior or middle Cerebellar ataxiacerebellar peduncle

Medial longitudinal fasciculus Internuclear ophthalmoplegia

Contralateral to lesion

Structures involved Signs and symptoms

Corticobulbar and corticospinal tract Paralysis of face,UE and LE

(6)-LATERAL SUPERIOR PONTINE SYNDROME

Occlusion of superior cerebellar artery,a branch of the basilar artery.

Ipsilateral to lesion

Structures involved Signs and symptoms

Middle and superior cerebellar Cerebellar ataxia of limbspeduncles,superior surface of and gait, falling to side ofcerebellum,dentate nucleus lesion

Vestibular nuclei Dizziness,nausea,vomitingHorizontal nystagmus

Structures involved Signs and symptoms

Descending sympathetic fibers Horner’s syndrome: miosis,ptosis,decreasedsweating on opposite side face

Uncertain Paresis of conjugate gaze(ipsilatereal),Loss of optokinetic nystagmus

Contralateral to lesion

Structures involved Signs and symptoms

Spinothalamic tract Impaired pain and thermal sense of face,limbs and trunk

Medial lemniscus(lateral portion) Impaired touch, Vibration,and position sense,more in LE than UE (tendency to incongruity of pain and touch deficits)

The midbrain forms the upper end of the narrow stalk ofbrainstem.

As it ascends out of the posterior cranial fossa through therelatively small rigid opening in the tentorium cerebelli,it isvulnerable to traumatic injury.

It possesses two important cranial nerve nuclei(Oculomotor and trochlear), reflex centers(the colliculi),and theRed nucleus and substantia nigra, which greatly influence motorfunction and the midbrain serves as a conduit for many importantascending and descending tracts.

As in other parts of the brainstem,it is a site fortumors,hemorrhage,or infercts that will produce a wide variety ofsymptoms and signs.

1)-PARINAUD’S SYNDROME

Lesion location Midbrain dorsum

Structures involved Quadrigeminal plate region; pretectum;periaqueductal gray matter

Clinical findings Impaired upgaze;convergenceretraction nystagmus;dilated pupils with light near dissociation

Comment Usually due to mass lesion in the region of the posterior third ventricle,most often pinealoma, or due to midbrain infarction

2)-WEBER’S SYNDROME

Lesion location Midbrain base

Structures involved CN III ,fibers’cerebral peduncle

Clinical findings Ipsilateral CN III palsy’ contralateral hemiparesis

Comment Usually vascular

3)-BENEDIKT’S SYNDROME

Lesion location Midbrain tegmentum

Structures involved CN III fibers,Red nucleus,CST,SCP

Clinical findings Ipsilateral CN III palsy’contralateralhemiparesis with ataxia,hyperkinesisand tremor “rubral tremor”

Comment Usually vascular

4)-CLAUDE’S SYNDROME

Lesion location Midbrain tegmentum

Structures involved CN III fibers; Red nucleus; SCP

Clinical findings Ipsilateral CN III palsy; contralateralataxia and tremor(rubral tremor)

Comment Usually vascular