Neuroanatomical Localisation Flashcards
What is the focal pattern of weakness?
In distribution of peripheral nerve or spinal root, hemi-distribution, pyramidal distribution
What is the non-focal pattern of weakness?
Generalised = predominantly proximal or distal
Includes bulbar motor function if truly generalised (otherwise quadri/tetraparesis)
What is the distribution of UMN weakness?
Corticospinal, hemiparesis, quadriparesis, paraparesis, monoparesis, faciobrachial
What are some features of UMN pattern?
Central pattern sensory loss
Increased deep tendon reflexes (flaccid if very acute)
decreased superficial reflexes
Increased pathological reflexes
Sometimes impaired sphincter function
Increased muscle tone and muscle hypertrophy
What are some features of LMN pattern?
Normal/decreased deep tendon reflexes
Normal superficial and pathological reflexes
Usually normal sphincter function -except cauda equina
Normal/decreased muscle tone with muscle wasting
What is the UMN patter of weakness?
Increased tone with brisk reflexes
Pyramidal or corticospinal pattern = weakness in arm extensors and leg flexors
What is the LMN pattern of weakness?
Wasting, fasciculation, decreased tone and absent/decreased reflexes, flexor plantars
What is the muscle disease pattern of weakness?
Wasting = usually proximal
Decreased tone
Absent/decreased tendon reflexes
What is the NMJ pattern of weakness?
Fatiguable weakness
Normal or decreased tone
Normal tendon reflexes and no sensory symptoms
What is the pattern of functional weakness?
No wasting, normal tone and reflexes, erratic power, non-anatomical loss
What can cause UMN lesions in the CNS?
Acute stroke, space occupying lesions and spinal cord problems
What are some patterns of UMN lesions?
Hemispheric = contralateral pyramidal weakness in face, arms or legs
Spinal cord = pyramidal weakness below level of lesion (cervical = arms and legs, thoracolumbar = legs)
Parasagittal frontal lobe lesion = paraparesis
What causes LMN lesions in anterior horn cells?
Motor neuron disease and spinal muscular atrophy
What are some causes of LMN lesions in peripheral nerves?
Diabetes, alcohol or metabolic insults
How may LMN lesions in peripheral nerves present?
Symmetrical polyneuropathy with weakness and sensory symptoms
Mononeuropathy due to nerve compression
Mononeuritis multiplex due to diabetes or vasculitis
What are the nerves and muscles involved in shoulder abduction and elbow extension?
Shoulder abduction = deltoid muscle, axillary nerve, C5 nerve root
Elbow extension = triceps muscle, radial nerve, C7 nerve root
What are the nerves and muscles involved in finger extension and index finger abduction?
Finger extension = extensor digitorum, posterior interosseous nerve, C7 nerve root
Index finger abduction = first dorsal interosseous, ulnar nerve, T1 nerve root
What muscles and nerves are involved in hip and knee flexion?
Hip flexion = iliopsoas muscle, femoral nerve, L1-2 nerve roots
Knee flexion = hamstring muscle, sciatic nerve, S1 nerve root
What muscles and nerves are involved in ankle dorsiflexion?
Peroneal muscle = innervated by common peroneal and sciatic nerves, L4-5 nerve roots
What are the roots of the deep tendon reflexes?
Ankle = S1-2 Knee = L3-4 Biceps = C5-6 Triceps = C7-8
What are some patterns of sensory loss?
Stocking = implies length dependent neuropathy
Dermatomal = mononeuropathy, radicular/plexus lesion
Sensory level = implies spinal cord lesion
What does hemianaesthesia suggest?
Contralateral cerebral lesion or a non-organic disorder if there is an absence of other signs
What symptoms are suggestive of hemicord damage?
Dissociated sensory loss with lost spinothalamic but preserved dorsal column
What are the signs of cerebellar dysfunction?
Broad based and unsteady gait
Intention tremor, ataxia, nystagmus, dysarthria
Dysdiadochokinesis = clumsy fast alternating movements
How is an intention tremor or ataxia assessed?
Arms = finger-nose test
Legs = knee-heel test
Tremor gets worse nearer to target
What are the characteristic features of extrapyramidal symptoms (Parkinsonism)?
Bradykinesia, rigidity, resting tremor and impaired gait/posture
What are some additional extrapyramidal symptoms?
Hypomimia and hypophonia
Reduced arm swing, stooped posture, small steps, festination, turning en bloc and impaired postural reflexes
How can symptom distribution be used to differentiate between different causes of Parkinsonism?
Asymmetry = Parkinson's disease Symmetry = drug induced or atypical Parkinson's
What is the function of the frontal lobe?
Generates novel strategies and executive functions
What are some features of the orbitofrontal cortex?
Responds to primitive stimuli
Damage causes disinhibition
What is the function of the dorsolateral prefrontal cortex?
Responds to external stimuli
What are the cingulate gyrus and dorsomedial frontal lobe responsible for?
Motivation = damage causes lack of will or even akinetic mutism
What are some signs of frontal lobe dysfunction?
Personality dysfunction, paraparesis, paratonia, magnetic gait, cortical hand, seizures, incontinence, visual field defects, expressive dysphasia, anosmia
What are some signs of temporal lobe dysfunction?
Memory dysfunction = especially episodic memory
Agnosia and temporal lobe epilepsy
Congruous upper homonymous quadrantanopia
Auditory and limbic dysfunction
Receptive aphasia
What are some signs of parietal lobe dysfunction?
Congruous lower homonymous quadrantanopia
Sensory dysfunction, dyspraxia, inattention and denial
Gerstmann’s syndrome
What is Gerstmann’s syndrome?
Disease of the dominant angular gyrus = dysgraphia, left-right disorientation, finger agnosia, acalculia
What is the treatment of Parkinson’s disease?
Levodopa or dopamine agonists
MAO-B inhibitors may be used as add on or alone
Anticholinergics have severe side effects
Amantadine may help resting tremor
What are the symptoms of Parkinson’s disease?
Asymmetrical = resting tremor, rigidity, bradykinesia, postural instability
What does postural instability lead to in Parkinson’s disease?
Falls = usually late in disease course
What would be a strong indicator that a patient doesn’t have idiopathic Parkinson’s disease?
Failure to respond to large doses of levodopa
What is a common side effect of levodopa?
Dyskinesia
What are some features of multiple sclerosis?
Symptoms = visual compromise, stiffness, weakness
Symptoms may worsen after fever or high temperature
May have lesions on MRI without clinical compromise directly related to those lesions
What are some features that would indicate a patient has had an ischaemic stroke?
Sudden onset, focal signs and symptoms usually in keeping with a vascular territory, usually negative symptoms (ie loss of function)
How common is intracerebral haemorrhage as a cause of stroke?
Account for 10% of all strokes
What imaging can be used to identify strokes?
MRI T1/2 and FLAIR = old lesions, non-vascular lesions
T2 = bleeds and microbleeds
Time of flight sequences and diffusion weighted image
CT
What are diffusion weighted images used to identify?
New ischaemic lesions (hyperintensities) and a decrease in signal on apparent diffusion coefficient of water
What do time of flight sequences identify?
Occlusions of extra and intracranial arteries
What may a CT show in a patient with an ischaemic stroke?
Hyperintensities = bleeds
Subtle ischaemic signs in acute phase of stroke = loss of lentiform nucleus limit, poor white matter differentiation, loss of insular ribbon
What are some features of lacunar strokes?
No visual field defect or higher cortical/brainstem issue
Pure motor hemiparesis, pure sensory unilateral deficit, sensorimotor/ataxic hemiparesis
At least two of face, arm or leg involved
What is needed to diagnose a posterior circulation stroke?
Any 1 of = cranial nerve palsy, cerebellar dysfunction, unilateral or bilateral motor/sensory deficit, disorder of conjugate eye movements, homonymous hemianopia or cortical blindness
What are the symptoms of a total anterior circulation stroke?
Hemiplegia and homonymous hemianopia contralateral to lesion
Either aphasia or visuospatial disturbances
May also have sensory deficit contralateral to lesion
What is needed to diagnose a partial anterior circulation stroke?
One or more of = unilateral motor or sensory deficit, aphasia, visuospatial neglect (with or without homonymous hemianopia)
How can you differentiate between a partial anterior circulation stroke and a lacunar stroke?
Motor or sensory deficits may be more extreme in a lacunar stroke
