Localising Lesions Flashcards
what are movement disorder features arise from lesions in the corticospinal/ pyramidal tracts
pyramidal/ UMN features:
pyramidal weakness (corticospinal distribution: hemiparesis, quadriparesis, paraparesis, monoparesis, faciobrachial) spascticity
what are the types of movement disorders that arise from lesion in the basal ganlgia
(extrapyramidal) hyperkinetic - dystonia - tics - myoclonus - chorea - tremor
hypokinetic (rigidity and bradykinesia)
- parkinsonism
- parkinson’s disease
what movement disorders arise from the cerebellum
ataxia
what makes up the peripheral nervous system
spinal nerve
root
plexus
peripheral nerves
what are the features of focal weakness
in distribution of peripheral nerve or spinal root
hemi-distribution (one side of body)
pyramidal distribution
what is pyramidal distribution weakness
where the extensors are weaker in the arms and the flexors are weaker in the legs
what are the features of non focal weakness
generalised
predominantly proximal or distal
if truely generalised will include bulbar motor function
UMN weakness:
distribution
corticospinal
- hemiparesis
- quadriparesis
- paraparesis
- monoparesis
- faciobrachial
LMN weakness:
distribution
generalised
predominantly proximal, distal or focal
no preferential involvement of corticospinal innervated muscles
UMN weakness:
Sensory loss
central pattern
LMN weakness:
Sensory loss
- can be none
- glove
- stocking
- peripheral nerve or root distribution
UMN weakness:
- deep tendon reflexes
- superficial reflexes
- pathological reflexes
deep- increased (unless very acute= flaccid)
superficial- decreased
pathological- increased
LMN weakness:
- deep tendon reflexes
- superficial reflexes
- pathological reflexes
deep- normal/ decrease
superficial- normal
pathological- normal
what are the superficial reflexes
plantar
gag/ swallow
cremasteric
corneal
what are the pathological reflexes
babinski (upward plantar, fanning and hyperextension of the toes), hoffmans etc
UMN weakness:
sphincter function
sometimes impaired
LMN weakness:
sphincter function
usually normal (except in cauda equina)
UMN weakness:
muscle tone
increased
LMN weakness:
muscle tone
decreased/ normal
UMN weakness:
muscle bulk
sometimes hypertrophy
LMN weakness:
muscle bulk
wasting
UMN weakness:
other CNS signs?
possibly
LMN weakness:
other CNS signs?
no
increased tone, brisk reflexes, pyramidal/ corticospinal pattern of weakness (= weak extensors in the arm, weak flexors in the legs) = ?
upper motor neurone pattern
wasting, fasciculation, decreased tone, decreased or absent reflexes, flexor plantars = ?
lower motor neurone pattern
what are the features of muscle disease
wasting (usually proximal)
decreased tone
decreased/ absent tendon reflexes
what are the features of NMJ weakness
fatiguable weakness
normal/ decreased tone
normal reflexes
NO SENSORY SYMPTOMS
what are the features of functional weakness
no wasting normal tone normal reflexes erratic power non anatomical loss
what causes UMN weakness
acute stroke syndromes
space occupying lesions
spinal cord problems
what weakness results from a hemispheric lesion
contralateral pyramidal weakness in face, arm, leg
what results from a parasagittal frontal lobe lesion
paraparesis
what UMN weakness results from a spinal cord lesion
pyramidal weakness below the level of the lesion
if cervical spine- arms and legs
if thoracolumbar- legs
what part of spinal cord do lower motor neurones attach to
anterior horn
what can cause a lower motor neurone lesion in the anterior horn cells
motor neurone disease
spinal muscular atrophy
lead poisoning, poliomyelitis etc
what are the two patterns of lower motor lesions in peripheral nerves
symmetrical (often length dependant):
- polyneuropathy with weakness and sensory symptoms: can be complication of diabetes, alcohol, metabolic insults
mononeuropathy:
- result of nerve compression (carpal, ulnar tunnel, radial neuropathy) or
- mononeuritis multiplex (asymmetric polyneuropathy) (occurs in diabetes or vasculitis)
what are the features of a median nerve mononeuropathy
thumb abduction paresis
thenar atrophy
sensory loss - thumb, second, third fingers, lateral 1 half of fourth finger
e.g. carpal tunnel syndrome
what are the features of a ulnar nerve mononeuropathy
finger and thumb adduction paresis
sensory loss- fifth and medial one half of fourth finger
what are the features of a radial nerve mononeuropathy
wrist, thumb and finger extension (wrist drop)
brachioradialis DTR lost
sensory loss on dorsum of hand
e.g. saturday night palsy
what are the features of a femoral nerve mononeuropathy
knee extensor paresis
loss of quads DTR
sensory loss over anterior thigh and medial calf
what are the features of a sciatic nerve mononeuropathy
ankle dorsiflexions and plantarfelxion paresis (flail ankle)
loss of achilles DTR
sensory loss on buttock, lateral calf, most of foot
e.g. caused by herniated disc
what are the features of a fibular nerve mononeuropathy
ankle dorsiflexion and evertors paresis (foot drop)
sensory loss on dorsum of foot and lateral calf
e.g. foot drop
what do NMJ disorder occur in
acetylecholine receptor antibodies mediated myasthenia gravis:
-ocular/ generalised
inhibition of acetylcholinesterase by organophosphate poisoning
lambert-eaton paraneoplastic syndrome
-interference with presynaptic calcium channel function
what can cause muscle disorders
inflammatory endocrine (e.g. hypothyroidism, cushings, electrolyte abnormalities) metabolic disorders durgs and toxins infections rhabdomyelisis
shoulder abduction: name the -muscle -nerve -nerve root
deltoid
axillary
C5
elbow extension: name the -muscle -nerve -nerve root
triceps
radial
C7
finger extension: name the -muscle -nerve -nerve root
extensor digitorum
posterior interossues (radial)
C7
index finger abduction: name the -muscle -nerve -nerve root
first dorsal interosseus
ulnar
T1
hip flexion name the -muscle -nerve -nerve root
iliopsoas
femoral
L1,2
knee flexion name the -muscle -nerve -nerve root
hamstrings
sciatic
S1
ankle dorsiflexion name the -muscle -nerve -nerve root
peroneals
common peroneal and sciatic
L4,5
great toe dorsiflexion name the -muscle -nerve -nerve root
extensor hallucis longus
common peroneal
L5
what roots innervate the ankle DTR
S1,2
what roots innervate the knee DTR
L3,4
what roots innervate the biceps DTR
C5,6
what roots innervate the triceps DTR
C7,8
what does stocking (and later glove) sensory loss suggest
length dependent neuropathy
what is length dependent neuropathy
a polyneuropathy= it is the longest nerve-fibers that are most at risk, while the shorter
nerve-fibers are less affected. In brief, polyneuropathy is a “length-dependent” neuropathy. Because the
longest nerve-fibers in the body are those that run from the lower back to the feet, in typical cases of
polyneuropathy the first part of the body to become weak or numb is the feet.
what does a sensory level loss suggest
spinal cord lesion
what does hemianaesthesia suggest
contralateral cerebral lesion
what does dissociated sensory loss suggest (loss of spinothalamic (temp and pain) but reserved dorsal column (vibration, light tough, proprioception)
hemi cord damage (anterior spinal artery syndrome, brown sequard, syringomyelia)
what are the cerebellar signs
gait is broad-based and unsteady
Intention tremor / ataxia is assessed in the arms by finger-nose test and in the legs by knee-heel testing. Tremor gets exaggerated the nearer the target
Dysdiadochokinesis: clumsy fast alternating movements
Nystagmus and dysarthria are additional features of cerebellar disorders
what are extrapyramidal symptoms/ parkisonism
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 role of the frontal lobe
generates novel strategies and has executive functions. It enables self-criticism and trying again
Orbitofrontal cortex: response to primitive stimuli (hunger, thirst, sexual function) damage causes disinhibition
Dorsolateral prefrontal cortex: response to external stimuli (executing work resposnibilities)
Cingulate gyrus and dorsomedial frontal lobe: motivation, damage causes abulia (lack of will) or even akinetic mutism
what does the prefrontal cortex connect to
other association cortices, basal ganglia, limbic system, thalamus and hippocampus
what symptoms can arise from damage to the frontal lobe
Personality dysfunction
Paraparesis
Paratonia
Grasp reflex
Frontal gait dysfunction (magnetic gait)
Cortical hand
Seizures
Incontinence
Visual field defects (anterior visual pathway incl optic chiasms are beneath frontal lobe)
Expressive dysphasia (Broca’s area is in the dominant frontal lobe)
Anosmia (olfactory pathway is beneath frontal lobes)
what symptoms can arise from temporal lobe disorders
Memory dysfunction especially episodic memory
Agnosia (visual and sensory modalities in particular)
Language disorders receptive 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
what symptoms can arise from damage to the parietal lobe
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
what is the treatment protocol for parkinsons
Symptomatic treatment with Levodopa replacement or dopamine agonist
Multidisciplinary team management including Speech and language, OT, PT, exercise
For selected patients deep brain stimulation (subthalamic nucleus, globus pallidus int)
how does levodopa work
crosses the blood brain barrier while dopamine does not. Levodopa is then converted to dopamine in the brain while peripheral break down is prevented by the addition of ‘inhibitors of aromatic amino acid decarboxylase (carbidopa). Thus a carbidopa/levodopa formulation is often prescribed.
name some dopamine agonists used in PD
pramipexole, ropinirole, and bromocriptine
what other drugs can be used in PD
MAO-B inhibitors such as selegiline and rasagiline can improve symptoms in patients with mild disease (as monotherapy) as well patients already on levodopa.
Anticholinergics such as trihexyphenidyl or diphenhydramine (Benadryl) aim to combat tremor, but usually cause severe side effects
Amantadine blocks NMDA receptors and has a mild attenuation of resting tremor and dystonia. May alleviate levodopa induced dyskinesias.
is PD usually symmetrical or asymmetrical
asymmetrical
what does failure to respond to even high doses of levodopa mean in PD
suggests it is not idiopathic PD
what can levodopa cause in PD
dyskinesias
what is primary lateral sclerosis
a presentation of MND
pure upper motor neurone syndrome
what imaging for stroke
MRI T1/T2 and FLAIR images to identify old lesions and lesions of non-vascular origin
Diffusion weighted images (DWI) to identify new ischemic lesions (hyperintensities)
T2 to identify bleeds and microbleeds
Perfusion-weighted images (PWI) may be useful to identifies brain areas at risk of ischemia
CT brain: hyperintenisities – bleed, subtle ischemic signs in the acute phase of stroke (may be normal, early signs: loss of limits of lentiform nucleus, poor grey white matter differentiation, loss of insular ribbon)
what are the features of a lacunar syndrome
No visual field defect
No new higher cortical or brainstem dysfunction
Pure motor hemiparesis, or pure sensory deficit of one side of the body, or 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
what are the symptoms of a posterior circulation syndrome (stroke)
any one of: Cranial nerve palsy Unilateral or bilateral motor or sensory deficit Disorder of conjugate eye movements Cerebellar dysfunction Homonymous hemianopia Cortical blindness
what are the symptoms of a total anterior circulation syndrome (stroke)
Hemiplegia and homonymous hemianopia contralateral to the lesion, and
Either aphasia or visuospatial disturbances
+/- sensory deficit contralateral to the lesion
what are the symptoms of a partial anterior circulation syndrome
One or more of unilateral motor or sensory deficit, aphasia or visuospatial neglect (with or without homonymous hemianopia)
Motor or sensory deficit may be less extensive than in lacunar syndromes
