Principles of Neurological Diagnosis

1. Localization2. Etiology

Example 1 A 25 YO male, acute paraparesis

with urinary incontinence, severe LBP:

Localization: spinal cord Etiology: acute disc herniation

Example 2 A 75 YO female with diabetes and

HBP, sudden weakness of left side limbs

Localization: right hemisphere Etiology: intracerebral hemmorhage

Gross Anatomy of the CNS

Subsystems for this talk Motor system Sensory system Visual and ocular Blood supply

Motor system Lower motor neuron Upper motor neuron (origin of the corticospinal tract) Brainstem nuclei that project to the cord Basal ganglia Cerebellum Premotor frontal cortex Prefrontal cortex

Lower motor neuron Motor unit Fasciculation Weakness & atrophy Root – plexus – nerve

Upper motor neuron

Origin at prerolandic motor cortex

Humunculus, somato-topic arrangement

Posterior capsule Isolated movements

evoked by electrical stimulation

Paralysis due to UMN lesion

Weakness distribution (additional systems, crossed syndromes, sparing of midline bilateral muscles)

‘Classic UMN’ picture: spasticity, increased tendon reflexes, positive Babinski’s, (spinal shock)

Patterns of paralysis

Monoplegia without atrophy Monoplegia with atrophy Hemiplegia Paraplegia Tetraplegia

Cortico BulbarTract

Basal ganglia

Negative signs: hypokinesia, bradykinesia

Positive signs: involuntary movements

Extrapyramidal Clinico-Pathological Correlations

SymptomMorbid anatomy

Unilateral Rigidity + TremorContralat Substantia Nigra

Unilateral hemibalismusContralat subthalamic nuc (Luis)

choreaCaudate and putamen

Cerebellar dysfunction Incoordination – ataxia (dysmetria, dysdiadochokinesis) Intention tremor Dysarthria (slurred speech) Nystagmus Disordered gait and equilibrium

Sensory system

Skin or visceral sense organs Distribution by nerve, root,

CNS Primary afferent (DRG) Spinal tracts:

Dorsal columns Spinothalamic Spinocerebellar

Thalamus and cortex Descending analgesic tract

Dorsal Columns

Sensory dysfunction

Positive - paresthesia, pain, allodynia, hyperalgesia

Negative – hypesthesia, anesthesia, analgesia

Symptoms and Signs in Neurology

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MotorFasciculationInvoluntary Movement

Weakness paralysis

Hypotonia

SensoryParesthesia, pain, allodynia,

hyperalgesia

Hyp/anesthesiaHyp/analgesia

AutonomicHyperhydrosisDiarrhea

ImpotenceOrthostatism

Visual system Retina, optic nerve, chiasm, tract, radiation, cortex

Ocular movements

Blood supply

Circle of Willis

MRA of the Circle of Willis

Middle cerebral artery

Ant & Post Cerebral Arteries

Exercise I

30 YO man, weakness of right lower limbOn exam:Weak, spastic, hyper-reflexic right legLoss of touch on Rt legLoss of pain and temp. on Lt legHemi-Sensory level D8

Spino DorsalThalamic Columns

Exercise II

70 YO female, weakness of right side, speech difficulty

On exam: Rt hemiparesis Motor

dysphasia

Exercise III

60 YO male, Rt side weakness

On exam: Rt hemi-

paresis Lt facial

weakness