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Localization in the Neuraxis. Fawaz Al- hussain Assistant Professor Stroke Neurologist For Internal Medicine Round Nov.10 th /2010. The Approach to a Patient with Neurologic Disease. Localization is important investigation modalities differ widely depending upon the level affected.
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Localization in the Neuraxis Fawaz Al-hussain Assistant Professor Stroke Neurologist For Internal Medicine Round Nov.10th/2010
The Approach to a Patient with Neurologic Disease • Localization is important • investigation modalities differ widely depending upon the level affected
Divisions of the Neuraxis • Cortical Brain • Subcortical area • Brainstem • Cerebellum • Spinal Cord • Root • Peripheral Nerve • Neuromuscular Junction • Muscle
Neurologic Examination Higher Cortical Function Cranial Nerves Motor Sensory Deep Tendon Reflexes Coordination Special tests Gait
Divisions of the Neuraxis • Cortical Brain • Subcortical area • Brainstem • Cerebellum • Spinal Cord • Root • Peripheral Nerve • Neuromuscular Junction • Muscle
Cortical Brain • Depends upon hemispheric dominance • Non-neurologists generalize: • right: visual/spatial, perception and memory • left: language and language dependent memory • Through detailed examination, neurologists should lateralize and localize within a lobe
Cortical Brain • Frontal Lobe: • L: • Broca’s Aphasia • R: ? • Both: • Primary motor cortex: motor homunculous • supplementary motor cortex: • Voluntary eye field • prefrontal cortex: personality, initiative
Cortical Brain • Parietal Lobe: R: Lt hemispatial neglect dressing and constructional apraxia L: Gerstman’s Tetrad: L/R confusion, finger agnosia, acalculia, agraphia without alexia Werneke’s Aphasia (with Temporal lobe) Both: cortical sensory modalities
Cortical Brain • Temporal: • Auditory cortex: Heschel’s gyrus • learning and memory: mid/inferior gyri • olfaction: limbic system • (Lt): Werneke’s Aphasia
Cortical Brain • Occipital Lobe: • Micropsia/ macropsia • visual hallucinations: elemental and unformed • prosopagnosia: familiar faces • cortical blindness: striate cortices, normal pupil rx
Divisions of the Neuraxis • Cortical Brain • Subcortical area • Brainstem • Cerebellum • Spinal Cord • Root • Peripheral Nerve • Neuromuscular Junction • Muscle
Subcortical Brain Deep white radiating fibers • weakness • sensory abnormalities Visual radiating fibers: • deep parietal: bilateral inferior homonomousquadronopsia • deep temporal (Meyer’s loop): bilateral superior homonomousquadronopsia Basal Ganglia: extrapyramidal signs
Divisions of the Neuraxis • Cortical Brain • Subcortical area • Brainstem • Cerebellum • Spinal Cord • Root • Peripheral Nerve • Neuromuscular Junction • Muscle
Brainstem The Brainstem is basically spinal cord with embedded cranial nerves • Cranial neuropathies • Long Tract signs: (bilateral and crossed) • corticospinal (pyramidal): motor • spinothalamic: pain/temp • dorsal columns: proprioception/vibration • Autonomic dysfunction (LOC, eyes, mouth, heart, breathing)
Divisions of the Neuraxis • Cortical Brain • Subcortical area • Brainstem • Cerebellum • Spinal Cord • Root • Peripheral Nerve • Neuromuscular Junction • Muscle
Cerebellar Function Pure cerebellar signs cerbellum Cerebellar and long tracts’ signs brainstem
Divisions of the Neuraxis • Cortical Brain • Subcortical area • Brainstem • Cerebellum • Spinal Cord • Root • Peripheral Nerve • Neuromuscular Junction • Muscle
Spinal Cord 3 Functions: Motor UMNL Sensory Autonomic Key ? sensory level
Divisions of the Neuraxis • Cortical Brain • Subcortical area • Brainstem • Cerebellum • Spinal Cord Motor neurons (upper & lower) • Root • Peripheral Nerve • Neuromuscular Junction • Muscle
Motor neurons Pure motor deficit(s) • Upper (primary Lateral sclerosis) in motor cortex • Lower motor neurons in spinal cord Spread: leg arm bulbar bulbar arm and leg
Divisions of the Neuraxis • Cortical Brain • Subcortical area • Brainstem • Cerebellum • Spinal Cord • Root • Peripheral Nerve • Neuromuscular Junction • Muscle
Root/Radiculopathy Radicular pain:hallmark Sensory abnormalities in a dermatomes Weaknessin a myotomaldistn
Divisions of the Neuraxis • Cortical Brain • Subcortical area • Brainstem • Cerebellum • Spinal Cord • Root • Peripheral Nerve • Neuromuscular Junction • Muscle
Peripheral Nerve(presuming nonfocality) Weakness (LMN) Numbness +/- autonomic all are consistent with PN distribution
Divisions of the Neuraxis • Cortical Brain • Subcortical area • Brainstem • Cerebellum • Spinal Cord • Root • Peripheral Nerve • Neuromuscular Junction • Muscle
Neuromuscular Junction • Fatigability: hallmark • Weakness: proximal and symmetric • muscles have normal bulk and tone • EOMs, bulbar, arms, and legs • Sensation: preserved
Divisions of the Neuraxis • Cortical Brain • Subcortical area • Brainstem • Cerebellum • Spinal Cord • Root • Peripheral Nerve • Neuromuscular Junction • Muscle
Muscle • Weakness • Symmetric • Proximal • + atrophy & absent DTRs • Sensation is normal • though patients complain of cramping, & aching • myalgia
Few Things to Remember Accurate Hx and P/E are needed Some neurologic diseases hit more than one level in the neuraxis include all involved Never fabricate part of the exam Always localize before making DDx list The localization plus the tempo of progression allow one to narrow a differential diagnosis
Case-1 32 y/o male with reduced endurance and mild weakness in his legs His older brother has weakness too P/E: mild atrophy in legs with fasciculation but increased muscle tone. (N) sensory exam Localize?
Case-1 32 y/o male with reduced endurance and mild weakness in his legs His older brother has weakness too P/E: mild atrophy in legs with fasciculation but increased muscle tone. (N) sensory exam Localize? Motor Neuron Disease familial ALS
Case-2 55 y/o lady with sudden diplopia and weakness in Rt (F,A,L) Localize?
Case-2 55 y/o lady with sudden diplopia and weakness in Rt (F,A,L) Localize? Midbrain lesion ischemic stroke
Case-3 75 y/o lady with increased misnaming stuff over 2 years P/E: decreased lexical fluency and some paraphasic errors No other neurological signs Localize?
Case-3 75 y/o lady with increased misnaming stuff over 2 years P/E: decreased lexical fluency and some paraphasic errors No other neurological signs Localize? Lt frontal lobe frontal dementia
Case-4 35 y/o man with Rt blindness, dysarthria, dysphagia, and weakness in Rt arm and leg plus Lt leg and sensory level at T-4 Localize?
Case-4 35 y/o man with Rt blindness, dysarthria, dysphagia, and weakness in Rt arm and leg plus Lt leg and sensory level at T-4 Localize? Multiple lesions at least brainstem and T-spine MS
Case-5 16 y/o girl with gait ataxia and poor coordination in 4 limbs + nystagmus when looks to Rt side Localize?
Case-5 16 y/o girl with gait ataxia and poor coordination in 4 limbs + nystagmus when looks to Rt side Localize? cerebellar spinocerebellar ataxia
Case-6 50 y/o lady with diplopia on/off worse at evenings In exam: partial ptosis in Rt eye Localize?
Case-6 50 y/o lady with diplopia on/off worse at evenings In exam: partial ptosis in Rt eye Localize? NM junction Myasthenia gravis