Pattern recognition Flashcards
What are the features of an upper motor neuron pattern?
Increased tone, brisk reflexes, pyramidal/corticospinal pattern of weakness i.e. weak extensors in the arms, weak flexors in the legs
What are the features of a lower motor neuron pattern?
Wasting, fasciculation, decreased tone, decreased or absent reflexes, flexor plantars/Babinski sign
What are the features of muscle disease?
Wasting (usually proximal), decreased tone, decreased or absent tendon reflexes
What are the features of neuromuscular junction injury?
- Fatiguable weakness, normal or decreased tone, normal tendon reflexes
- No sensory symptoms
What are the features of functional weakness?
No wasting, normal tone, normal reflexes, erratic power, non-anatomical loss
What can cause UMN lesions?
- Acute stroke syndrome, space occupying lesions and spinal cord problems
- Can usually be determined by body segments involved and accompanying signs e.g, hemispheric - contralateral pyramidal weakness in face, arm and leg
What can cause LMN lesions in the anterior horn cells?
Occurs with motor neuron disease, spinal muscular atrophy, lead poisoning, poliomyelitis
What can cause LMN lesions in the peripheral nerves and how does this present?
- Symmetrical polyneuropathy with weakness and sensory symptoms - frequent complication of diabetes. Other causes include alcohol or metabolic insults as well as heritable disorders
- Mononeuropathy as a result of nerve compression (carpal or tarsal tunnel syndrome, ulnar neuropathy, radial neuropathy) or mononeuritis multiplex which occurs in the context of diabetes or vasculitis
What can cause neuromuscular junction injury and how does it present?
- Presents with purely fatiguable motor symptoms
- Occurs in acetylcholine receptor antibody mediated myasthenia gravis, inhibition of acetylcholinesterase by organophosphate poisoning, or interference with presynaptic calcium channel function in Lambert-Eaton paraneoplastic syndrome
What can cause muscle disorders and how do they present?
- Often symmetrical, often proximal, very wide differential diagnosis
- Inflammatory e.g. polymyositis, vasculitis
- Endocrine e.g. hypothyroidism, Cushing’s
- Drugs and toxins e.g. alcohol, cocaine, steroids
- Infections e.g. HIV, pyomyositis, toxoplasmosis
- Rhabdomyolisis
What nerve and nerve root supplies the deltoid muscle? What movement does the deltoid muscle control?
Axillary nerve, C5 nerve root, controls shoulder abduction
What nerve and nerve root supplies the triceps muscle? What movement does the triceps muscle control?
Radial nerve, C7, controls elbow extension
What nerve and nerve root supplies the iliopsoas muscle? What movement does the iliopsoas muscle control?
Femoral nerve, L1, 2, controls hip flexion
What nerve and nerve root supplies the hamstring muscles? What movement do the hamstring muscles control?
Sciatic, S1, controls knee flexion
What nerve and nerve root supplies the peroneal muscles? What movement do the peroneal muscles control?
Common peroneal and sciatic, L4, 5, controls ankle dorsiflexion
What nerve and nerve root supplies the extensor hallucis longus muscle? What movement does the extensor hallucis longus muscle control?
Common peroneal, L5, controls great toe dorsiflexion
What nerve roots innervate the ankle reflex?
S1, 2
What nerve roots innervate the knee reflex?
L3, 4
What nerve roots innervate the biceps reflex?
C5, 6
What nerve roots innervate the triceps reflex?
C7, 8
What does a stocking (and later glove) distribution of sensory loss suggest?
Length dependent neuropathy
What does a sensory level pattern of sensory loss suggest?
Spinal cord lesion
What does a hemianaesthesia suggest?
Contralateral cerebral lesion, or with no other signs a non-organic disorder
What does dissociated sensory loss suggest?
Loss with lost spinothalamic (pain/temperature) but preserved dorsal column (fine touch, vibration, proprioception) suggests hemicord damage (Brown-Sequard syndrome, syringomyelia, anterior spinal artery syndrome)
What are cerebellar signs?
- Cerebellar 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
- Dysdiadochokinesis
- Nystagmus and dysarthria are additional features of cerebellar disorders
- DANISH - dysdiadochokinesis, ataxia, nystagmus, intention tremor, speech problems, hypotonia
What are extrapyramidal symptoms/Parkinsonism?
- 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 does the frontal lobe control?
Generates novel strategies and has executive functions. It enables self-criticism and trying again. The prefrontal cortex connects extensively to other association cortices, basal ganglia, limbic system, thalamus and hippocampus
What are some signs associated with frontal lobe dysfunction?
Personality dysfunction, paraparesis, paratonia, grasp reflex, seizures, incontinence, visual field defects, expressive dysphasia (Broca’s area), anosmia (olfactory pathway)
What are some signs associated with temporal lobe dysfunction?
Memory dysfunction, agnosia, receptive dysphasia (Wernicke, dominant hemisphere), visual field defects (superior quadrantopia), auditory dysfunction, limbic dysfunction, temporal lobe epilepsy
What are some signs associated with parietal lobe dysfunction?
Visual field defect (inferior quadrantopia) sensory dysfunction, Gerstmann’s syndrome (Dysgraphia, left-right disorientation, finger agnosia, acalculia), dyspraxia, inattention, denial
What is used to treat Parkinson’s disease?
Levodopa - crosses the BBB while dopamine does not, levodopa is then converted into dopamine in the brain
What drug is often used concomitantly with levodopa when managing PD?
COMT inhibitors - levodopa can be broken down by catechol-O-methyltransferase (COMT) so COMT inhibitors such as entacapone are often used
What are the cardinal features of PD?
- Resting tremor, rigidity, bradykinesia and postural instability
- PD is usually asymmetrical
- Postural instability leading to falls occurs relatively late in the clinical course of PD
What are the cardinal features of multiple sclerosis (MS)?
- Visual compromise, stiffness and weakness
- MS can have lesions on MRI without clinical compromise directly related to those lesions
- Oligoclonal bands in the CSF are also found in other conditions
- The symptoms of MS can worsen with fever
Describe the clinical presentation of motor neuron disease
- Progressive muscular atrophy accounts for 10% although most eventually develop UMN signs
- Primary lateral sclerosis is a pure upper motor syndrome
- Usually it is a mix of UMN and LMN abnormalities in the absence of sensory disturbances
- Cognitive impairment may be part of the presentation
- Ask about cramps, fasciculations, foot drop, family history and behavioural changes
- Frontotemporal dementia
How is imaging used to investigate stroke?
- MRI T1/2 and FLAIR images to identify old lesions and lesions of non-vascular origin
- Diffusion weighted images to identify new ischaemic lesions
- T2 to identify bleeds and microbleeds
- Perfusion weighted images may be useful to identify brain areas at risk of ischaemia
- CT brain - hyperintensities
What are the clinical features of 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
- At least 2 of the 3 areas (face, arm, leg) should be involved in its entity
What are the clinical features of posterior circulation syndrome?
Cranial nerve palsy, unilateral or bilateral motor or sensory deficit, disorder of conjugate eye movements, cerebellar dysfunction, homonymous hemianopia, cortical blindness
What are the clinical features of total anterior circulation syndrome?
Hemiplegia and homonymous hemianopia contralateral to the lesion and either aphasia or visuospatial disturbances +/- sensory deficit contralateral to the lesion
What are the clinical features of 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 syndrome
