Pattern recognition in Neurology Flashcards
What is focal weakness?
- Weakness in distribution of peripheral nerve or spinal root
- Hemi-distribution
- Pyramidal distribution
What is non-focal weakness?
- generalised
- predominantly proximal or distal
- if truly generalised: including bulbar motor function otherwise quadri- or tetraparesis
UMN weakness will be in what distribution?
Corticospinal distribution;
hemiparesis, quadriparesis,
paraparesis, monoparesis,
faciobrachial
LMN weakness will be in what distribution?
Generalised, predominantly proximal, distal or focal.
No preferential involvement of corticospinal innervated muscles.
Sensory loss in UMN weakness will be in a _____ pattern
Sensory loss in UMN weakness will be in a central pattern
Deep tendon reflexes are ______ (unless very acute: ____) in UMN weakness
Deep tendon reflexes are increased (unless very acute: flaccid) in UMN weakness
Superficial reflexes are ______ in UMN weakness?
Superficial reflexes are decreased in UMN weakness?
Pathological reflexes are ______ in UMN weakness, sphincter dunction is ______ impaired, muscle tone is ______. There may be some muscle ________.
Pathological reflexes are increased in UMN weakness, sphincter dunction is sometimes impaired, muscle tone is increased. There may be some muscle hypertrophy.
LMN sensory loss will be;
None, glove, stocking, peripheral nerve or root distribution
Deep tendon reflexes are ______ or ______ in LMN pathology, superficial reflexes are _____ along with pathological reflexes.
Sphincter function is ______ ______ (unless for example; _____ _____ ______)
Muscle tone is _______ or _______ and muscles may show signs of ______.
Deep tendon reflexes are normal or decreased in LMN pathology, superficial reflexes are normal along with pathological reflexes.
Sphincter function is usually normal (unless for example; cauda equina lesion)
Muscle tone is normal or decreased and muscles may show signs of wasting.
What is a pyramidal/corticospinal pattern of weakness?
Weak extensors in the arm, weak flexor in the leg
What is a lower motor neurone pattern of disease?
wasting, fasciculation, decreased tone, decreased or absent reflexes, flexor plantars
How does muscle disease present?
Wasting (usually proximal), decreased tone, decreased or absent tendon reflexes
How does NMJ disease present?
Fatiguable weakness, normal or decreased tone, normal tendon reflexes. No sensory symptoms.
How does functional weakness present?
No wasting, normal tone, normal reflexes, erratic power, non-anatomical loss
When does UMN disease occur?
Acute stroke syndromes, SOL, spinal cord problems
How can UMN lesions be located?
Determined by body segments involved and accompanying signs
How does a hemispheric UMN lesion present?
Contralateral pyramidal weakness in face, arm , leg- homunculus
How does a parasagittal frontal lobe UMN lesion present?
Paraparesis
How does a spinal cord UMN lesion present?
Pyramidal weakness below the level of the lesion
- cervical: arms and legs
- thoracolumbar: legs
What is a LMN lesion presentation?
wasting, fasciculation, decreased tone, decreased or
absent reflexes, flexor plantars
What causes LMN anterior horn cell lesions?
MND, spinal muscular atrophy, lead poisoning, poliomyelitis
How does peripheral nerve involvement present
- Symmetrical (often length dependent) polyneuropathy with weakness and sensory symptoms: frequent complication of diabetes. Other aetiologies include a variety of toxic (alcohol) or metabolic insults as well as heritable disorders (often young onset and skeletal deformities)
- Mononeuropathy as a result of nerve compression (carpal or tarsal tunnel syndrome, ulnar neuropathy, radial neuropathy) or mononeuritis multiplex (asymmetric polyneuropathy), which occurs in the context of diabetes or vasculitis
How does median nerve mononeuropathy present?
Motor pareses of thumb abduction with thenar atrophy
Thumb, secon, third fingers and lateral fourth finger- pain or sensory loss
What causes median nerve mononeuropathy?
Carpal tunnel
How does ulnar nerve mononeuropathy present?
Claw hand
Where is the pain/sensory loss in ulnar mononeuropathy?
Fifth and medial one-half of fourth finger
How does radial nerve mononeuropathy present?
Wrist drop
Which DTR is lost in radial nerve mononeuropathy?
Brachioradialis- compression of the radial nerve in the spiral groove of the humerus spares the triceps DTR
Where is the pain/sensory loss in radial nerve mononeuropathy?
Dorsum of hand
What is a common cause of radial nerve palsy?
Saturday night palsy
What is affected in femoral nerve mononeuropathy?
Knee extensors
Which DTR is lost in femoral nerve mononeuropathy?
Quadriceps
Where is the pain/sensory loss in femoral nerve mononeuropathy?
Anterior thigh, medial calf
What is affected by sciatic nerve mononeuropathies?
Ankle dorsiflexors and plantarflexors (flail ankle)
Which DTR is lost in sciatic nerve palsy?
Achilles
Where is pain/sensory loss in sciatic nerve palsy?
Buttock, lateral calf and most of foot
What is a common cause of sciatic nerve mononeuropathy?
Sciatica from a herniated disk
What is affected by fibular nerve mononeuropathy?
Ankle dorsiflexors and evertors (foot drop)
Where is the pain and sensory loss in fibular nerve mononeuropathy?
Dorsum of foot and lateral calf
When does NMJ weakness occur?
- acetylcholine-receptor (Musk) antibody mediated myasthenia gravis- ocular or generalised
- inhibition of acetylcholinesterase by organophosphate poisining
- interference with presynaptic calcium channel function in lambert-eaton paraneoplastic syndrome
Limb movement Muscle Nerve Nerve root
Shoulder abduction ______ _______ ________
Elbow extension ______ _______ ________
Finger extension ______ _______ ________
Index finger abduction ______ _______ ________
Hip Flexion ______ _______ ________
Knee Flexion ______ _______ ________
Ankle Dorsiflexion ______ _______ ________
Great Toe Dorsiflexion ______ _______ ________
Limb movement Muscle Nerve Nerve root
Shoulder abduction DeltoidAxillaryC5
Elbow extension TricepsRadialC7
Finger extension Extensor DigitorumPost. interosseusC7
Index finger abduction first dorsal interosseusUlnarT1
Hip Flexion IliopsoasFemoralL1, 2
Knee Flexion HamtringsSciaticS1
Ankle Dorsiflexion PeronealsCommon peroneal and sciaticL4, 5
Great Toe Dorsiflexion Extensor hallucis longusCommon PeronealL5
What is the root innervation/deep tendon reflex of the ankle?
S 1,2
What is the root innervation/deep tendon reflex of the knee?
L3, 4
What is the root innervation/deep tendon reflex of the biceps?
C5, 6
What is the root innervation/deep tendon reflex of the triceps?
C7, 8
Stocking (and later glove) sensory loss implies _____ _______ _______
Stocking (and later glove) sensory loss implies length dependant neuropathy
Dermatomal sensory loss can point towards _________, _______ or ______ lesion
Dermatomal sensory loss can point towards mononeuropathy, radicular or plexus lesion
Sensory level loss of sensation implies a ______ ____ lesion
Sensory level loss of sensation implies a spinal cord lesion
Hemianaesthesia suggests contralateral _______ lesion, or with no other signs a ___________ disorder
Hemianaesthesia suggests contralateral cerebral lesion, or with no other signs a non-organic disorder
Dissociated sensory loss with lost ____________ (temperature/pain) but preserved ______ ______ (vibration, light touch, proprioception) suggests _______ damage (anterior spinal artery syndrome, brown-sequard syndrome, syringomyelia)
Dissociated sensory loss with lost spinothalamic (temperature/pain) but preserved dorsal colums (vibration, light touch, proprioception) suggests hemicord damage (anterior spinal artery syndrome, brown-sequard syndrome, syringomyelia)
Describe a cerebellar gait
Broad-based and unsteady
What ar the cerebellar signs?
- broad-based gait and unsteadiness
- intention tremor/ataxia
- dysdiadochokinesis
- Nystagmus
- Dysarthria
How is intention tremor/ataxia assessed in the arms and legs?
arms- By a finger nose test
legs- knee-heel testing
Tremor is exaggerated near the target
What is dysdiadochokinesis?
Clumsy fast alternating movements
What are the motor extrapyramidal symptoms?
Bradykinesia, Rigidity, resting tremor, impaired gait and posture
Hypomimia
Hypophonia
Reduced arm swing, stooped posture, small steps, festination, turning en bloc
Impaired postural reflexes
Asymmetry in PD, symmetry in drug induced or atypical PD
What is the function of the frontal lobe?
Generates novel strategies and has executive functions. Enables self-criticism and trying again. The prefrontal cortex connects extensively to other association cortices; basal ganglia, limbic system, thalamus and hippocampus.
What is the role of orbitofrontal cortex?
Response to primitive stimuli (hunger, thirst, sexual funciton)
Damage of orbitofrontal cortex results in what?
Disinhibiiton
What is the role of the dorsolateral prefrontal cortex?
Response to external stimuli (executing work responsibilities)
What is the role of the cingulate gyrus and dorsomedial frontal lobe?
Motivation
Damage to the cingulate gyrus and dorsomedial frontal lobe causes what?
abulia (lack of will) or even akinetic mutism
Pathology in the temporal lobe can cause
- Memory dysfunction especially episodic memory
- Agnosia (visual and sensory modalities in particular)
- Language disorders eceptive dysphasia (Wernicke, dominant hemisphere)
- Visual field defects (congruous upper homonymous quadrantanopia)
- Auditory dysfunction (Heschel’s gyrus, as hearing is represented bilaterally, deafness is not a cerebral feature)
- Limbic dysfunction
- Temporal lobe epilepsy
Damage to parietal lobe can cause?
- Visual field defect (congruous lower homonymous quadrantanopia)
- Sensory dysfunction (visual and sensory modalities in particular)
- Gerstmann’s syndrome (disease of the dominant angular gyrus, part of the inferior parietal lobe): Dysgraphia, left-right disorientation, finger agnosia, acalculia
- Dyspraxia
- Inattention (non-dominant angular gyrus)
- Denial
Can levodopa cross the BBB
yes
Does dopamine cross the BBB
no
what prevents the peripheral breakdown of levodopa?
inhibitors of aromatic amino acid decarboxylase
Levodopa can be broken down by what enzyme and how can this be prevented?
atechol-O-methyltransferase (COMT), so COMT inhibitors such as entacapone and tolcapone are often employed
How do dopamine agonists work?
Cross the BBB and act directly as D2- type receptors
Name dopamine agonists
pramipexole, ropinirole, and bromocriptine
How can MAO-B inhibitors be useful in PD?
selegiline and rasagiline can improve symptoms in patients with mild disease (as monotherapy) as well patients already on levodopa
How can anticholinergics be used in PD?
trihexyphenidyl or diphenhydramine (Benadryl) aim to combat tremor, but usually cause severe side effects
How does amantadine work in PD?
blocks NMDA receptors and has a mild attenuation of resting tremor and dystonia. May alleviate levodopa induced dyskinesias
What are frequent presenting symptoms in MS?
Visual compromise, stiffness, and weakness
How can symptoms of MS be made acutely worse?
With fever or higher temperatures
What imaging is used to identify old stroke lesions and lesions of non-vascular origin?
MRIT1/T2 and FLAIR
When is diffusion weighted imaging used?
to identify new ischemic lesions (hyperintensities) and a decrease in signal on the apparent diffusion coefficient of water (ADC map)
What is T2 weighted imaging used for
to identify bleeds and microbleeds
What are Time-of-flight sequences used to identify
Occulsions of the extra and intracranial arteries
What are perfusion-weighted images used to identify?
identifies brain areas at risk of ischemia
What is not found in lacunar stroke syndrome?
Visual defect
new higher or cortical brainstem dysfunction
What is seen in lacunar stroke
- Pure motor hemiparesis
- pure sensory deficit of one side of the body
- sensorimotor hemiparesis or ataxic hemiparesis (dysarthric clumsy hand syndrome or ipsilateral ataxia with crural hemiparesis)
– At least 2 of the 3 areas (face,arm,leg) should be involved in its entity
How does posterior circulation syndrome present?
(any one of):
- Cranial nerve palsy
- Unilateral or bilateral motor or sensory deficit
- Disorder of conjugate eye movements
- Cerebellar dysfunction
- Homonymous hemianopia
- Cortical blindness
How does total anterior circulation syndrome present?
- hemiplegia and homonymous hemianopia contralateral to the lesion
AND
- either aphasia or visuospatial disturbances
- +/- sensory deficit contralateral to the lesion
How does partial anterior circulation syndrome present?
- one or more of;
- unilateral motor or sensory deficit
- aphasia
- visuospatial neglect (with or without homonymous hemianopia)
Motor or sensory deficit may be less extensive than in lacunar syndromes
