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 demyelinating diseases, neoplasms, and vascular disorders.

(1) Medial medullary syndrome occlusion of vertebral artery medullary branch .

Ipsilateral to lesion Structures involved CN XII,hypoglossal,or nucleus

Signs and symptoms 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 arteries Ipsilateral to lesion Structures involved

Signs and symptoms

Descending tract and nucleus of CN V,Trigeminal

decreased pain and temperature sensation in face

Ceraballum or inferior cerebellar peduncle

cerebellar ataxia: gait and 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 CN X,vagus, or nuclei

Dysphagia and dysphonia: 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

Spinal lemniscus-spinothalamic tract

Signs and symptoms

impaired pain and thermal 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 gaze paramedian pentine reticular formation(PPRF)

Paralysis of conjugate gaze to side of lesion(preservation of convergence)

Vestibular nuclei and connections

Nystagmus

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 tract in lower pons

Paresis of face ,UE and 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 CN VIII(Vestibular) or nucleus

CN VII(Facial )or nucleus

Signs and symptoms Horizontal and vertical nystagmus,vertigo,nausea, vomiting Facial paralysis

Structures involved

Signs and symptoms

Pontine center for lataral gaze(PPRF)

Paralysis of conjugate gaze to side of lesion

CN VIII(Cochlear )or nucleus

Deafness,tinnitus

Middle cerebellar peduncle and cerebellar hemisphere

Ataxia

Main sensory nucleus and descending tract of fifth nerve

impaired sensation over 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 CN V(trigeminal)

Paralysis of muscles of mastication

Sensory fibers or nucleus of CN V (trigeminal)

Impaired sensation over 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 peduncle

Cerebellar ataxia

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 peduncles,superior surface of cerebellum,dentate nucleus

Cerebellar ataxia of limbs and gait, falling to side of lesion

Vestibular nuclei

Dizziness,nausea,vomiting Horizontal nystagmus

Structures involved

Signs and symptoms

Descending sympathetic fibers

Horner’s syndrome: miosis,ptosis,decreased sweating 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 of brainstem. As it ascends out of the posterior cranial fossa through the relatively small rigid opening in the tentorium cerebelli,it is vulnerable to traumatic injury. It possesses two important cranial nerve nuclei (Oculomotor and trochlear), reflex centers(the colliculi),and the Red nucleus and substantia nigra, which greatly influence motor function and the midbrain serves as a conduit for many important ascending and descending tracts. As in other parts of the brainstem,it is a site for tumors,hemorrhage,or infercts that will produce a wide variety of symptoms and signs.

1)-PARINAUD’S SYNDROME Lesion location

Midbrain dorsum

Structures involved

Quadrigeminal plate region; pretectum;periaqueductal gray matter

Clinical findings

Impaired upgaze;convergence retraction 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’contralateral hemiparesis with ataxia,hyperkinesis and 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; contralateral ataxia and tremor(rubral tremor)

Comment

Usually vascular