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Cerebellum NMJ Brachial Plexus, Median, Radial, and Ulnar nerves

LOCALIZATION. Cerebellum NMJ Brachial Plexus, Median, Radial, and Ulnar nerves. Cerebellum [17 cm x 120cm]. Anatomy Relation 3 Lobes Functional 4 deep nuclei fastigial Interposed x 2 dentate Topography Blood supply. Vermis  Ms mvt of the axial body

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Cerebellum NMJ Brachial Plexus, Median, Radial, and Ulnar nerves

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  1. LOCALIZATION Cerebellum NMJ Brachial Plexus, Median, Radial, and Ulnar nerves

  2. Cerebellum [17 cm x 120cm] • Anatomy • Relation • 3 Lobes • Functional • 4 deep nuclei • fastigial • Interposed x 2 • dentate • Topography • Blood supply

  3. Vermis Ms mvt of the axial body The intermediate zone distal portion of the limbs & face The lateral zone [has no topographic representation] Input  motor & premotor areas of the frontal cortex & somatosensory & sensory ass. area of the parietal cortex  overall planning & coordination of rapid sequential mvts  Incoordination

  4. Functions • Timing, in rapid progression • Intensity of muscle contraction • Continuously updated info. • Makes corrective adjustments when actual mvt unfavorably compares with the intended • Performs most of the damping function • Aids the C.Cx in planning next mvt  smooth progression • Ballistic mvts [typing, guitar] loss of automaticity • Control the interplay b/n agonist & antagonists, +synergists & fixators • Extramotor predictive function:- rate of progression of auditory and visual phenomenon

  5. Afferent pathways Brain • Corticopontocerebellar Pathway to lat zone • Olivocerebellar tract to all areas • Vestibuloc. fibers floculonod lobe & Fastigial N. • Reticulocerebellr fibers vermis Periphery • Dorsal spinocerebellar tract  vermis & IM zone same side • From ms spindles and somatic • Ventral spinocerebellar tract [fastest] • SCP Both side • By Motor signals arriving at AHC [“efference copy of the ant horn motor drive]

  6. Major Efferent pathways • Midlinefastigial N.  medullary & pontine fastigiobulbar & C.reticular tracts • Equilibrium apparatus & vestibular N.  Equil. • Reticular formation postural attitude • IM zoneinterposed NC. reticular & C. .olivery fs • Thalamus Cx,  BG,  to the red N and RF • Coordinate reciprocal contraction of limbs ms • Lateral zonedentate N.  thalamus  Cx Dentatothalamic & Dentatorubral fs • coordination of sequential motor activity

  7. Summary: It controls motor fn at 3 level • The Vestibulocerebellum [archicerebellum] •  floculonodular + adjacent vermis •  Equilibrium and postural mvts • The Spinocerebellum [paleocerebellum] •  IM zone  comparison  interposed N corrective signal • Smooth coordinated mvt of agonist and antagonist ms of distal limb for acute purposeful patterned mvt • Damping & ballistic mvt fn • Cerebrocerebellum [Neocerebellum] • Lateral zone & dentate N • Extreme incoordin. of cx purposeful mvts of hands,fingers, & feet & of speech apparatus • Planning & Timing of sequential mvts • Extramotor predictive function

  8. Clinical Abnormalities • Small lesion /  !/2 removed • Imbalance and Ataxia • Truncal ataxia wide based gait • Not lateralized +/- Symmetric nystagmus  toxic, metabolic, inflammatory or neurodegenerative dis. • Asymmetric ataxia  structural dis. Ischemia, tumor or mass lesion • Visual cues • C. limb ataxia • Dysmetria • Dysdiadochokinesia • Tremor • Past pointing / rebound • C. nystagmus • Hypotonia • Dysarthria

  9. Cerebellar Syndromes • The Rostral Vermis Sundrome [ant.lobe] • Wide-based stance and gait • Ataxia of Gait vs. heel-to shin • Arm coordination Nl/impaired • Hypotonia/nystagmus/dysarthria  infrequent Cerebellar cortical degeneration of Chr. Alcoholics • Ant & sup vermis

  10. Caudal Vermis Synd [Floculonodular & post lobe] • Axial dysequilibirium & staggering gait • Little or no limb ataxia • +/- nystagmus &rotated head posture • S/S of Inc ICP medulloblastoma

  11. Cerebellar Hemispheric Synd • Mvts requiring fine coord. [ms controlled by the precentral cx] Infarcts, neoplasm, and abscesses • Pancerebellar Syndrome • Trunk, limbs, cranial ms • Infectious and parainfectious, Hypoglycemia, hyperthermia, paraneoplastic d/o, and other toxic-metabolic d/os

  12. Syndromes of cerebellar infarction • Thrombotic or embolic • Limb & gait ataxia, dysarthria, nyst, & altered mental sttus • With/without BS and 4th vent compression • Large occiputal headache vetigo, N/V, gait unsteadiness and dysarthria,  obst hydrocephalus •  neck stiffness, • Herniation CR sx VS. MB compression • PICA, SCA or both • Border zone not easily localizable • 47 pts: cardiac arrest [4%], Atheroma or hypercoagulable state [20%], Large art VB occlusive dis. [34%], Brain embolism [23%], unknown mechanism [19%]

  13. Approach • Hx  Duration, Neurologic Sx, Alcohol, Nutritional… • Exam –sensory/ motor • Evaluation for Vit. B12 def. • Imaging studies

  14. Neuromuscular Junction Dis. • Fatigable/ ptosis, diplopia or bulbar weakness • Proximal weakness • Normal mental fn, • Fluctuating • Ms tone/Reflexes/Atrophy • Most often gradual

  15. Major causes of intermittent generalized weakness are: • Electrolyte disturbances • Ms disorders [channelopathies, metabolic defects] • NMJ disorders [MG, LEMS] • Myopathic  proximal and are rarely limited to the limbs • Proximal weakness of 2/4 limbs ms, less commonly, NMJ or AHC • Myopathy pelvic or shoulder girdle ms • NM disorders such as MG  Proximal weakness ass with ptosis,diplopia or bulbar weakness & fluctuating in severity during the day • The proximal weakness of AHC dis asymmetric •  Numbness is absent in all •  sensation is intact

  16. Myasthenia Gravis • Autoantibody anti AchR • The most common [1 in 7500]] • Fatigable weakness • The cranial ms Early • Diplopia, ptosis, Chewing, speech, regurgitation, aspiration • 85%  generalized • DTR & sensation preserved • Response to Tx, RNS

  17. DDX • Neurasthenia  nonorganic • Drug induced myasthenia • LEMS presynaptic/ auto Ab against Ca++ channels[85%] • Often ass with malignancy • Hyper-/hypothyroidism inc. myasthenic weakness • Grave’s disease VS. ocular MG • Botulism pupil and Incremental RNS • Intracranial mass lesion • Congenital myasthenic syndrome

  18. The Brachial Plexus • C5-T1 to the entire UL + shoulder and neck ms • root, trunk, division, cords and branches. • 5 major nerves: Axillary, Radial [posterior], Musculocutaneous [Lateral], Ulnar [medial] and Median [lateral + Medial] • Plexopathy Diffuse  focused study of PNs • Radiculopthy sensation is spared • Most B.P regional involvement localizing to the specific region in the B.P 1st step then easy

  19. General rules • Weakness in a “myotomal” pattern C8 to T1 mslower trunk/medial cord C5 and C6 ms  upper trunk/lateral cord isolated to a single nr is unlikely to be of plexus origin, Inv’t of ms innervated by Radial & axill nrPost cord Isolated middle trunkunheard C7 radiculopathy Fixed sensory loss extending into the medial forearm  lower trunk/medial cord plexopathy; sensory loss extending into the lat forearm  upper trunk/lateral cord plexopathy

  20. Weakness of the serratus anterior radiculopathy or a component • Specific disorders of the brachial plexus • Downward movement of the shoulder results in an upper trunk disorder (Erb's palsy) • hyperabduction causes a lower trunk injury (Klumpke's palsy). • Lower trunk plexopathy by compression  TOS

  21. Upper trunk plexopathies may ff surgical intervention in the region of the neck. • Lower trunk plexopathies also can occur after chest-splitting cardiothoracic surgery. • Compression by tumors/masses  lower trunk plexopathies from “Pancoast tumors” • Backpack palsy —patients often present with arm/shoulder weakness after wearing a backpack for a prolonged period of time, suggestive of a predominantly upper trunk lesion. Some sensory loss is also present.

  22. RADICULOPATHY • Structural spine disease of the cervical spine remains one of the most frequent problems affecting the upper extremities. • In the young individual with an acute herniated disc, severe radiating pain, sensory loss, and weakness in muscles of the myotome of the affected nerve root can be present. • In the elderly- acute herniation of discs is uncommon; cervical spondylosis 2o to disc degeneration, calcification,… more frequent --.they often present present with more diffuse pain, sensory loss, and weakness.  involvement of multiple myotomes • Head turning, coughing, or sneezing may exacerbate symptoms, regardless of age. • C7 radiculopathies  70%. C6 n 19 to 25 %; C8 in 4 to 10 %; and C5 in 2 %.

  23. C5 radiculopathy — Sry lossproximal lat arm. Weakness  shoulder muscles including deltoid and biceps brachii . Biceps reflex- lost • C6 radiculopathy — Sry loss lat forearm and digit 1 of the hand. Weaknessbiceps and brachioradialis, deltoid, pronator teres, and triceps minimally. Biceps and brachioradialis reflex lost • C7 radiculopathy — Sry loss digits 2 to 4, with digit 3 most affected. Weakness triceps , wrist flexors, pronator teres, and wrist extensors. Triceps reflex lost. • C8 radiculopathy — Sry loss digit 5, medial hand, and medial forearm. Weakness finger flexors, thumb abduction, interossei, and finger extensors.

  24. MEDIAN NERVE SYNDROMES • Pronator teres syndrome [rare] • Entrapment in the proximal forearm  physically active . • Forearm pain and sry loss over entire lateral palm. Sry loss over the thenar eminence typical, Vs. from carpal tunnel syndrome • Anterior interosseous neuropathy br around the elbow.  innervates the flexor pollicis longus, the deep flexors of digits 2 and 3, and pronator quadratus. not sry; O/E: cannot make a standard "O"

  25. ULNAR NERVE SYNDROMES • At the elbow — Ulnar neuropathy is the 2nd most common compression neuropathy. sry loss and paresthesias over digits 4 and 5. & worsened grip and clumsiness. plus weakness in finger and wrist flexion. A prominent Tinel's sign • Epicondylar groovethe Tardy ulnar palsy • Entrapment as it enters the cubital tunnel • At the wrist same finding – finger flexers

  26. RADIAL NERVE SYNDROMES • At the spiral groove ffs prolonged pressure . "Saturday night palsy" • O/E the triceps is OK the wrist, finger extensors, and brachioradialis are weak. Sry loss over the dorsum of the hand, possibly extending up the posterior forearm. Thumb abduction is affected as abductor pollicis longus is a radial-innervated muscle. • Posterior interosseous neuropathy — nerve branches off just proximal to the elbow and innervates the extensor muscles of the forearm O/E medial deviation of the wrist

  27. The End

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