Brainstem

Views:
 
Category: Education
     
 

Presentation Description

clinical features of different brain-stem lesions

Comments

Presentation Transcript

PowerPoint Presentation: 

c linical features of different brainstem l esions s ubhraprakash p ramanik pgt, medicine, bmc, burdwan

PowerPoint Presentation: 

extremely important part of the brain as it connects cerebrum to other parts of CNS and includes the medulla oblongata ( myelencephalon ), pons (part of metencephalon ), and midbrain ( mesencephalon ). provides the main motor and sensory innervation to the face and neck via the cranial nerves . connects the motor and sensory systems from the main part of the brain to the rest of the body. plays an important role in the regulation of cardiac and respiratory function. also regulates the CNS, and is pivotal in maintaining consciousness and regulating the sleep cycle . anatomy

PowerPoint Presentation: 

Dorsal view Ventral view

PowerPoint Presentation: 

Internal structures of brainstem- Descending tracts Corticospinal tracts( main motor ) Corticonuclear tracts Corticopontocerebellar tracts Rubrospinal tracts Reticulospinal tracts Vestibulospinal tracts Medial longitudinal fasciculus Tectospinal tracts Ascending tracts Dorsal/posterior column tracts Medial lemniscus ( fine touch, vibration, proprioception )- fasciculus gracilis & fasciculus cuneatus Spinocerebellar tracts Spinal lemniscus – spinotectal, Spinothalamic( pain, temperature, crude touch ) spinoreticular tracts Lateral lemniscus Trigeminal lemniscus

PowerPoint Presentation: 

Cranial nerve nuclei Medulla - -hypoglossal nucleus -nucleus ambiguus -dorsal motor nucleus of vagus -nucleus of solitary fasciculus -vestibulo-cochlear nuclear complex -nucleus of the trigeminal spinal tract Pons - Abducent nerve nucleus Facial nerve nucleus Trigeminal nuclei – chief sensory nucleus & motor nucleus Midbrain- 3 rd & 4 th nerve nuclei, Mesencephalic nucleus of trigeminal

PowerPoint Presentation: 

The brainstem nuclei In the Medulla - gracile nucleus -Cuneate nucleus -Arcuate nucleus -Lateral cuneate nucleus Inferior olivary nuclear complex Inferior olivary nucleus Medial accessory olivary nucleus Dorsal accessory olivary nucleus Pontine nuclei Inferior salivatory nucleus Superior salivatory nucleus Red nucleus of midbrain Substancia nigra Reticular formation (polysynaptic neurones & nuclei )

PowerPoint Presentation: 

Anatomically , it comprises the tectum (or corpora quadrigemina), tegmentum , the cerebral peduncles, as well as several nuclei and fasciculi. Caudally the mesencephalon adjoins the pons (metencephalon) and rostrally it adjoins the diencephalon (Thalamus, hypothalamus, etc .). midbrain Midbrain internal structures Periaqueductal gray : CN III & CN IV nerve nucleus . Red Nucleus : Substantia nigra : Reticular formation :

PowerPoint Presentation: 

The corpora quadrigemina ("quadruplet bodies") are four solid optic lobes on the dorsal side of cerebral aqueduct- the superior posterior pair are called the superior colliculi, involved with saccadic eye movements ; and the inferior posterior pair are called the inferior colliculi, a synapsing point for sound information . The trochlear nerve comes out of the posterior surface of the midbrain, below the inferior colliculus . The cerebral peduncles are paired structures, present on the ventral side of cerebral aqueduct, and accommodate the corticospinal tract fibres, from the internal capsule. The middle part of cerebral peduncles carry substantia nigra , the only part of the brain that carries melanin pigment .

PowerPoint Presentation: 

( mnemonic for remembering the structures of the midbrain involves visualizing the mesencephalic cross-section as an upside down bear face. The two red nuclei are the eyes of the bear and the cerebellar peduncles are the ears.) Both sections will show the cerebral aqueduct, which connects the third and fourth ventricle and the periaqueductal gray. A transverse cross-section at the level of the superior colliculus shows the red nucleus, the nuclei of the oculomotor nerve (and associated Edinger-Westphal nucleus), the superior cerebellar peduncles or crus cerebri, and the substantia nigra . A horizontal cross section at the level of the inferior colliculus shows the substantia nigra. Also apparent are the trochlear nerve nucleus, and the decussation of the superior cerebellar peduncles The midbrain is usually sectioned at the level of the superior and inferior colliculi.

PowerPoint Presentation: 

appears as a broad anterior bulge rostral to the medulla. Posteriorly, it consists of two pairs of cerebellar peduncles- connecting the cerebellum to the pons and midbrain . includes tracts that conduct signals from the cerebrum down to the cerebellum and medulla, and tracts that carry the sensory signals up into the thalamus . The pons contains nuclei that relay signals from the forebrain to the cerebellum, along with nuclei that deal primarily with sleep, respiration, swallowing, bladder control, hearing, equilibrium, taste, eye movement, facial expressions, facial sensation, and posture . Within the pons is the pneumotaxic center , a nucleus in the pons that regulates the change from inspiration to expiration . The pons also contains the sleep paralysis center of the brain and also plays a role in generating dreams .

PowerPoint Presentation: 

A number of cranial nerve nuclei are present in the pons : mid-pons : The chief or pontine sensory nucleus of the trigeminal nerve(V ) the motor nucleus for the trigeminal nerve (V) lower down in the pons : abducens nucleus (VI), facial nerve nucleus (VII), vestibulocochlear nuclei (vestibular nuclei and cochlear nuclei) (VIII) The functions of these four nerves include sensory roles in hearing, equilibrium, and taste, and in facial sensations such as touch and pain; as well as motor roles in eye movement, facial expressions, chewing, swallowing and the secretion of saliva and tears.

PowerPoint Presentation: 

lower half of the brainstem; contains the cardiac, respiratory, vomiting and vasomotor centres and deals with autonomic, involuntary functions, such as breathing, heart rate and blood pressure . Two parts – - Closed part of medulla – fasciculus gracilis & fasciculus cuneatus - Open upper part of medulla - floor of 4 th ventricle Ventral view Pyramids containing the corticospinal tract. CN XII rootlets- Emerging from the anterolateral sulci Olives - containing underlying inferior olivary nuclei . CN IX , CN X & CN XI rootlets are lateral to the olives. CN VI , CN VII & CN VIII emerge from the Pontomedullary junction.

PowerPoint Presentation: 

Dorsal view Fasciculus gracilis , fasciculus cuneatus . gracile and cuneate tubercles , u nderlying these are their respective nuclei. The obex marks the end of the 4th ventricle and the beginning of the central canal.

PowerPoint Presentation: 

Reticular formation Part of the brain where traditional human soul is located, seat of consciousness that is involved in actions such as awaking/sleeping cycle. functions including : Somatic motor control - Cardiovascular control - The reticular formation includes the cardiac and vasomotor centers of the medulla oblongata . Pain modulation – Sleep and consciousness – Habituation – Reticular formation nuclei that modulate activity of the cerebral cortex are called the reticular activating system . Mass lesions in the brain stem cause severe alterations in level of consciousness such as coma due to their effects on the reticular formation. Bilateral damage to the reticular formation of the midbrain may lead to a coma or death .

PowerPoint Presentation: 

tegmentum located between the ventricular system and distinctive basal or ventral structures & forms the floor of the midbrain whereas the tectum forms the ceiling. a multisynaptic network of neurons that is involved in many unconscious homeostatic and reflexive pathways. divisions - Midbrain tegmentum - extending from the substantia nigra to the cerebral aqueduct. Pontine tegmentum- Lateral tegmental field- is the source of several neurons of the noradrenaline system of the brain Other pertinent areas of the tegmentum are : Ventral Tegmental А rea (VTA) Periaqueductal Gray Matter Reticular Formation Red Nucleus Substantia nigra Medial lemniscus pathway in the brainstem that carries sensory information from the gracile and cuneate nuclei to the thalamus . part of the posterior column-medial lemniscus system, which transmits touch, vibration sense and the proprioception.

PowerPoint Presentation: 

Blood supply of brainstem midbrain Medial part:- paramedian branches of upper basilar and proximal posterior cerebral arteries Lateral part:- small penetrating arteries arising from posterior cerebral artery pons The pontine arteries are a number of small vessels which come off at right angles from either side of the basilar artery . medulla Anterior spinal artery : supplies the whole medial part of the medulla oblongata. A blockage (such as in a stroke) will injure the pyramidal tract, medial lemniscus, and the hypoglossal nucleus. This causes a syndrome called medial medullary syndrome . Posterior inferior cerebellar artery (PICA): a major branch of the vertebral artery, supplies the posterolateral part of the medulla, where the main sensory tracts run and synapse. Direct branches of the vertebral artery : The vertebral artery supplies an area between the other two main arteries, including the nucleus solitarius and other sensory nuclei and fibers. Lateral medullary syndrome can be caused by occlusion of either the PICA or the vertebral arteries .

PowerPoint Presentation: 

Midbrain syndromes Axial section at the level of the midbrain, depicted schematically on the left, with a corresponding MR image on the right. Approximate regions involved in medial and lateral midbrain stroke syndromes are shown.

PowerPoint Presentation: 

Medial midbrain syndrome ( paramedian branches of upper basilar and proximal posterior cerebral arteries) On side of lesion Eye "down and out" secondary to unopposed action of fourth and sixth cranial nerves, with dilated and unresponsive pupil: Third nerve fibers On side opposite lesion Paralysis of face, arm, and leg: Corticobulbar and corticospinal tract descending in crus cerebri Lateral midbrain syndrome (syndrome of small penetrating arteries arising from posterior cerebral artery) On side of lesion Eye "down and out" secondary to unopposed action of fourth and sixth cranial nerves, with dilated and unresponsive pupil: Third nerve fibers and/or third nerve nucleus On side opposite lesion Hemiataxia, hyperkinesias, tremor: Red nucleus, dentatorubrothalamic pathway

PowerPoint Presentation: 

Axial section at the level of the superior pons, depicted schematically on the left, with a corresponding MR image on the right. Approximate regions involved in medial and lateral superior pontine stroke syndromes are shown.

PowerPoint Presentation: 

Signs and symptoms: Structures involved Medial superior pontine syndrome (paramedian branches of upper basilar artery) On side of lesion Cerebellar ataxia (probably): Superior and/or middle cerebellar peduncle Internuclear ophthalmoplegia : Medial longitudinal fasciculus Myoclonic syndrome, palate, pharynx, vocal cords, respiratory apparatus, face, oculomotor apparatus, etc.: Localization uncertain—central tegmental bundle, dentate projection, inferior olivary nucleus On side opposite lesion Paralysis of face, arm, and leg: Corticobulbar and corticospinal tract Rarely touch, vibration, and position are affected: Medial lemniscus

PowerPoint Presentation: 

Lateral superior pontine syndrome (syndrome of superior cerebellar artery) On side of lesion Ataxia of limbs and gait, falling to side of lesion: Middle and superior cerebellar peduncles, superior surface of cerebellum, dentate nucleus Dizziness, nausea, vomiting; horizontal nystagmus : Vestibular nucleus Paresis of conjugate gaze (ipsilateral): Pontine contralateral gaze Miosis , ptosis, decreased sweating over face (Horner's syndrome): Descending sympathetic fibers Tremor: Localization unclear — Dentate nucleus, superior cerebellar peduncle On side opposite lesion Impaired pain and thermal sense on face, limbs, and trunk : Spinothalamic tract Impaired touch, vibration, and position sense, more in leg than arm (there is a tendency to incongruity of pain and touch deficits ): Medial lemniscus (lateral portion )

PowerPoint Presentation: 

Axial section at the level of the midpons , depicted schematically on the left, with a corresponding MR image on the right. Approximate regions involved in medial and lateral midpontine stroke syndromes are shown.

PowerPoint Presentation: 

Medial midpontine syndrome ( paramedian branch of midbasilar artery) On side of lesion Ataxia of limbs and gait (more prominent in bilateral involvement): Pontine nuclei On side opposite lesion Paralysis of face, arm, and leg: Corticobulbar and corticospinal tract Variable impaired touch and proprioception when lesion extends posteriorly: Medial lemniscus Lateral midpontine syndrome (short circumferential artery) On side of lesion Ataxia of limbs: Middle cerebellar peduncle Paralysis of muscles of mastication: Motor fibers or nucleus of fifth nerve Impaired sensation over side of face: Sensory fibers or nucleus of fifth nerve On side opposite lesion Impaired pain and thermal sense on limbs and trunk: Spinothalamic tract

PowerPoint Presentation: 

Axial section at the level of the inferior pons, depicted schematically on the left, with a corresponding MR image on the right. Approximate regions involved in medial and lateral inferior pontine stroke syndromes are shown.

PowerPoint Presentation: 

Signs and symptoms: Structures involved Medial inferior pontine syndrome (occlusion of paramedian branch of basilar artery) On side of lesion Paralysis of conjugate gaze to side of lesion (preservation of convergence): Center for conjugate lateral gaze Nystagmus : Vestibular nucleus Ataxia of limbs and gait: Likely middle cerebellar peduncle Diplopia on lateral gaze: Abducens nerve On side opposite lesion Paralysis of face, arm, and leg: Corticobulbar and corticospinal tract in lower pons Impaired tactile and proprioceptive sense over one-half of the body: Medial lemniscus

PowerPoint Presentation: 

Lateral inferior pontine syndrome (occlusion of anterior inferior cerebellar artery) On side of lesion Horizontal and vertical nystagmus , vertigo, nausea, vomiting, oscillopsia : Vestibular nerve or nucleus Facial paralysis: Seventh nerve Paralysis of conjugate gaze to side of lesion: Center for conjugate lateral gaze Deafness, tinnitus: Auditory nerve or cochlear nucleus Ataxia: Middle cerebellar peduncle and cerebellar hemisphere Impaired sensation over face: Descending tract and nucleus fifth nerve On side opposite lesion Impaired pain and thermal sense over one-half the body (may include face): Spinothalamic tract

PowerPoint Presentation: 

Axial section at the level of the medulla, depicted schematically on the left, with a corresponding MR image on the right. Approximate regions involved in medial and lateral medullary stroke syndromes are shown.

PowerPoint Presentation: 

Signs and symptoms: Structures involved Medial medullary syndrome (occlusion of vertebral artery or of branch of vertebral or lower basilar artery ) On side of lesion Paralysis with atrophy of one-half o f the tongue: Ipsilateral twelfth nerve On side opposite lesion Paralysis of arm and leg, sparing face; impaired tactile and proprioceptive sense over one-half the body: Contralateral pyramidal tract and medial lemniscus

PowerPoint Presentation: 

Lateral medullary syndrome (occlusion of any of five vessels may be responsible—vertebral, posterior inferior cerebellar, superior, middle, or inferior lateral medullary arteries) On side of lesion Pain, numbness, impaired sensation over one-half the face: Descending tract and nucleus fifth nerve Ataxia of limbs, falling to side of lesion: Uncertain— restiform body, cerebellar hemisphere, cerebellar fibers, spinocerebellar tract (?) Nystagmus , diplopia, oscillopsia , vertigo, nausea, vomiting: Vestibular nucleus Horner's syndrome ( miosis , ptosis, decreased sweating): Descending sympathetic tract Dysphagia, hoarseness, paralysis of palate, paralysis of vocal cord, diminished gag reflex: Issuing fibers ninth and tenth nerves Loss of taste: Nucleus and tractus solitarius Numbness of ipsilateral arm, trunk, or leg: Cuneate and gracile nuclei Weakness of lower face: Genuflected upper motor neuron fibers to ipsilateral facial nucleus On side opposite lesion Impaired pain and thermal sense over half the body, sometimes face: Spinothalamic tract

PowerPoint Presentation: 

Total unilateral medullary syndrome (occlusion of vertebral artery): Combination of medial and lateral syndromes. Lateral pontomedullary syndrome (occlusion of vertebral artery): Combination of lateral medullary and lateral inferior pontine syndrome. Basilar artery syndrome (the syndrome of the lone vertebral artery is equivalent): A combination of the various brainstem syndromes plus those arising in the posterior cerebral artery distribution. Bilateral long tract signs (sensory and motor; cerebellar and peripheral cranial nerve abnormalities): Bilateral long tract; cerebellar and peripheral cranial nerves Paralysis or weakness of all extremities, plus all bulbar musculature: Corticobulbar and corticospinal tracts bilaterally

PowerPoint Presentation: 

Approach to patient Brainstem sign & symptoms:- Isolated cranial nerve abnormalities (single or multiple) "Crossed" weakness and sensory abnormalities of head and limbs, e.g., weakness of right face and left arm and leg

PowerPoint Presentation: 

THANK YOU