1. Localization in the Neuraxis
Fawaz Al-hussain Assistant Professor Stroke Neurologist For Internal Medicine Round

2. The Approach to a Patient with Neurologic Disease
Localization is important
investigation modalities differ widely depending upon the level affected

3. Divisions of the Neuraxis
Cortical Brain
Subcortical Brain
Brainstem
Cerebellum
Spinal Cord
Root
Peripheral Nerve
Neuromuscular Junction
Muscle

4. Neurologic Examination
Higher Cortical Function
Cranial Nerves
Motor
Sensory
Deep Tendon Reflexes
Coordination
Special tests
Gait

5. Divisions of the Neuraxis
Cortical Brain
Subcortical area
Brainstem
Cerebellum
Spinal Cord
Root
Peripheral Nerve
Neuromuscular Junction
Muscle

6. 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

7. Cortical Brain Frontal Lobe: L: R: ? Both: Broca’s Aphasia
Primary motor cortex: motor homunculous
supplementary motor cortex:
Voluntary eye field
prefrontal cortex: personality, initiative

8. Cortical Brain Parietal Lobe: R: L: 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

9. Cortical Brain Temporal: Auditory cortex: Heschel’s gyrus
learning and memory: mid/inferior gyri
olfaction: limbic system
Lt:
Wernicke's aphasia

10. Cortical Brain Occipital Lobe: Micropsia/ macropsia
visual hallucinations: elemental and unformed
prosopagnosia: familiar faces
cortical blindness: striate cortices, normal pupil rx

11. Divisions of the Neuraxis
Cortical Brain
Subcortical area
Brainstem
Cerebellum
Spinal Cord
Root
Peripheral Nerve
Neuromuscular Junction
Muscle

12. Subcortical Brain Deep white radiating fibers weakness
sensory abnormalities
Visual radiating fibers:
deep parietal: bilateral inferior homonomous quadronopsia
deep temporal (Meyer’s loop): bilateral superior homonomous quadronopsia
Basal Ganglia:
extrapyramidal signs

13. Divisions of the Neuraxis
Cortical Brain
Subcortical area
Brainstem
Cerebellum
Spinal Cord
Root
Peripheral Nerve
Neuromuscular Junction
Muscle

14. 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)

15. Divisions of the Neuraxis
Cortical Brain
Subcortical area
Brainstem
Cerebellum
Spinal Cord
Root
Peripheral Nerve
Neuromuscular Junction
Muscle

16. Cerebellar Function
Pure cerebellar signs  cerbellum Cerebellar and long tracts’ signs  brainstem

17. Divisions of the Neuraxis
Cortical Brain
Subcortical area
Brainstem
Cerebellum
Spinal Cord
Root
Peripheral Nerve
Neuromuscular Junction
Muscle

18. Spinal Cord
3 Functions: Motor  UMNL Sensory Autonomic Key ? sensory level

19. Divisions of the Neuraxis
Cortical Brain
Subcortical area
Brainstem
Cerebellum
Spinal Cord
Motor neurons (upper & lower)
Root
Peripheral Nerve
Neuromuscular Junction
Muscle

20. 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

21. Divisions of the Neuraxis
Cortical Brain
Subcortical area
Brainstem
Cerebellum
Spinal Cord
Root
Peripheral Nerve
Neuromuscular Junction
Muscle

22. Root/Radiculopathy Radicular pain: hallmark
Sensory abnormalities in a dermatomes
Weakness in a myotomal distn

23. Divisions of the Neuraxis
Cortical Brain
Subcortical area
Brainstem
Cerebellum
Spinal Cord
Root
Peripheral Nerve
Neuromuscular Junction
Muscle

24. Peripheral Nerve (presuming nonfocality)
Weakness (LMN)
Numbness
+/- autonomic
 all are consistent with PN distribution

25. Divisions of the Neuraxis
Cortical Brain
Subcortical area
Brainstem
Cerebellum
Spinal Cord
Root
Peripheral Nerve
Neuromuscular Junction
Muscle

26. Neuromuscular Junction
Fatigability: hallmark
Weakness: proximal and symmetric
muscles have normal bulk and tone
EOMs, bulbar, arms, and legs
Sensation: preserved

27. Divisions of the Neuraxis
Cortical Brain
Subcortical area
Brainstem
Cerebellum
Spinal Cord
Root
Peripheral Nerve
Neuromuscular Junction
Muscle

28. Muscle Weakness Sensation is normal Symmetric Proximal
+ atrophy & absent DTRs
Sensation is normal
though patients complain of cramping, & aching
myalgia

29. 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

30. 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?

31. 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

32. Case-2
55 y/o lady with sudden diplopia and weakness in Rt (F,A,L) Localize?

33. Case-2
55 y/o lady with sudden diplopia and weakness in Rt (F,A,L) Localize? Midbrain lesion  ischemic stroke

34. 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?

35. 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

36. 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?

37. 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

38. Case-5
16 y/o girl with gait ataxia and poor coordination in 4 limbs + nystagmus when looks to Rt side Localize?

39. 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

40. Case-6
50 y/o lady with diplopia on/off worse at evenings In exam: partial ptosis in Rt eye Localize?

41. 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