Clinical Signs Neurology Flashcards
How does cavernous sinus syndrome cause abducens nerve palsy?
Cavernous segment of the abducens nerve is located adjacent to the cavernous carotid artery, and is prone to compression by aneurysmal dilation of the vessel.
What is anosmia?
Anosmia is absence of the sense of smell.
What is hyposmia?
Decreased ability to recognise smells
What are main causes of anosmia?
- Upper respiratory tract infection (URTI)
- Chronic allergic or vasomotor rhinitis
- Trauma
- Cigarette smoking
- Normal ageing
- Alzheimer’s disease
- Meningioma
What are causes of an ataxic gait?
- Intoxication – alcohol
- Drug toxicity – lithium, phenytoin, benzodiazepine
- Cerebellar infarction
- Vertebral artery dissection
- Cerebellar mass lesion – tumour, abscess, AVM
- Multiple sclerosis
- HSV cerebellitis
- Hereditary cerebellar degeneration (Freidreich’s ataxia)
- Paraneoplastic cerebellar degeneration
What cerebellar structures are involved in someone who has truncal ataxia, diequilibrium and body sway?
Midline cerebellar structures
- Vermis
- Flocculonodular lobes
- Intermediate lobe
What might a lesion in the flocconodular lobe cause in terms of clinical signs?
- Multidirectional truncal instability
- Disequilibrium
- Severe impairment of trunk coordination
What are features of lateral cerebellar hemisphere dysfunction?
Ipsilateral abnormalities in:
- Coordinated leg movements
- Step timing, length and direction - typically slow and careful, and instability is accentuated during heel-to-toe walking.
Associated features
- Dysmetria
- Dysdiadochokinesis
- Intention tremor
What is dysmetria?
Dysmetria is a disturbance of the rate, range and force of movement of the extended limb as it approaches a target. Dysmetria is elicited during the finger-to-nose and heel-to-shin tests
What is dysmetria a sign of?
Dysmetria is a cerebellar sign
What causes dysmetria?
Lesions of the intermediate and lateral cerebellar hemispheres may cause slow, uncoordinated and clumsy movements of the ipsilateral distal extremity during attempted target localisation tasks. Delays in motor initiation and movement termination, and abnormalities of movement force and acceleration, contribute to dysmetria
What are causes of muscle atrophy?
- Muscle disuse – fracture, arthritis, prolonged immobility
- Lower motor neuron (LMN) disorders - Peripheral neuropathy, Radiculopathy, Motor neuron disease
- Peripheral vascular disease
- Poliomyelitis
How do lower motor neuron lesions cause muscle atrophy?
Loss of lower motor neuron input at the neuromuscular junction causes breakdown of actin and myosin, resulting in a decrease in cell size and involution of myofibrils
What is a positive babinski’s response?
The Babinski response, or upgoing plantar response, is an abnormal cutaneous reflex of the foot associated with upper motor neuron dysfunction. In a positive Babinski response, scratching the lateral plantar surface of the foot causes contraction of the extensor hallucis longus muscle and extension of the great toe.
What are causes of a positive babinski’s response?
Upper motor neuron lesions
- Cerebral infarction
- Cerebral haemorrhage
- Spinal cord injury
- Lacunar infarction, posterior limb internal capsule
- Multiple sclerosis
- SOL
What is thought to be the mechanism behind the development of the babinski response?
Before 1 or 2 years of age, a stimulus applied to the lower extremities, such as pressure or stroking of the plantar aspect of the foot, causes involuntary ankle dorsiflexion and great toe extension. The response is a primitive reflex that disappears later in life. After 1 or 2 years of age, normal development of the central nervous system extinguishes this response.
In a positive Babinski response, upper motor neuron dysfunction disrupts the normal plantar cutaneous reflex and the primitive response re-emerges. It may take hours or days for these signs to emerge, as it is often absent in acute/hyperacute setting
What are causes of bradykinesia?
- Parkinson’s disease
- Dopamine antagonists – haloperidol, metoclopramide
- Diffuse white matter disease – lacunar infarction(s)
- Multisystem atrophy
- Progressive supranuclear palsy
- Corticobasilar degeneration
What is Broca’s aphasia?
Expressive aphasia, is a disorder of speech fluency (i.e. word production). Comprehension is less affected. Patients demonstrate speech that is laboured and short, lacks normal intonation, and is grammatically simple and monotonous.
Typically, phrase length is decreased and the number of nouns is out of proportion to the use of prepositions and articles
What is the mechanism behind broca’s aphasia?
Broca’s aphasia is typically caused by a lesion in the posterior inferior frontal gyrus of the dominant hemisphere.
Which artery is most commonly implicated in someone with Broca aphasia due to a stroke?
Most commonly branches of the superior division of the middle cerebral artery (MCA)
What speech abnormalities are seen in broca’s aphasia?
- Nonfluent, mute or telegraphic spontaneous speech
- Dysarthria
- Impaired name recall
- Impaired writing and reading
What associated features can be present with Broca’s aphasia, and why can they be present?
Associated contralateral motor and sensory findings are more commonly associated with Broca’s aphasia, due to the proximity of the motor cortex to the vascular distribution of the superior division of the middle cerebral artery
What is Brown-Sequard syndrome?
Rare clinical syndrome caused by spinal cord hemisection and is characterised by:
-
Ipsilateral
- Below lesion - Weakness, Loss of light touch, vibration, proprioception and sensation below the lesion
- Level of lesion narrow band of ipsilateral complete sensory loss
-
Contralateral
- Below lesion - Loss of temperature and pain sensation
In brown-sequard syndrome, which spinal column tract is implicated in features of ipsilateral weakness and UMN signs?
Corticospinal tract lesion
In brown-sequard syndrome, which spinal column tract is implicated in features of ipsilateral loss of touch, vibration, proprioception below the lesion?
Dorsal column lesion
In brown-sequard syndrome, which spinal column tract is implicated in features of contralateral loss of pain and temperature below the level of the lesion?
Spinothalamic tract lesion
Why do those with Brown-Sequard syndrome develop contralateral loss of temp and pain sensation?
Lesion is above decussation at each spinal level, thus deficits are contralateral below the lesion
What can cause Brown-Sequard Syndrome?
- Penetrating trauma
- Multiple sclerosis
- Mass lesion – tumour, abscess, AVM
What is cavernous sinus syndrome?
Clinical syndrome of multiple cranial nerve abnormalities affecting the contents of the cavernous sinus
- Oculomotor nerve (CNIII)
- Trochlear nerve (CNIV)
- Ophthalmic division of the trigeminal nerve (CNV V1),
- Maxillary division of the trigeminal nerve (CNV V2)
- Abducens nerve (CNVI)
- Sympathetic fibres
What are causes of cavernous sinus syndrome?
- Septic thrombosis
- Aseptic thrombosis
- Cavernous carotid artery aneurysm
- Mucormycosis
- Pituitary apoplexy
- Cavernous – carotid sinus fistula
What is the most common cause of cavernous sinus syndrome?
Septic thrombosis
What nerve in the cavernous sinus is first affected in cavernous carotid artery aneurysm?
Abducens - due to its close proximity to the cavernous segment of the internal carotid artery
What is clasp-knife rigidity?
Brisk relaxation of hypertonic muscle groups during tone assessment. The name arises from the similarity of the phenomenon to opening and closing the blade of a pocket knife due to the action of the spring.
What are causes of clasp-knife rigidity?
UMN lesions
- Cerebral infarction
- Cerebral haemorrhage
- Cerebral palsy
- Multiple sclerosis
- Myelopathy
- Mass lesion – tumour, abscess, AVM
What is clonus?
A rhythmic, sustained muscular contraction initiated with a brisk stretching force in a muscle group. Clonus is most commonly elicited in the ankle by abrupt passive dorsiflexion. It can also be assessed in other locations, such as the quadriceps, finger flexors, jaw and other muscle groups
What are causes of clonus?
UMN lesions
- Cerebral infarction
- Cerebral haemorrhage
- Lacunar infarction, posterior limb internal capsule
- Multiple sclerosis
- Spinal cord injury
- Mass lesion – tumour, abscess, AVM
- Serotonin syndrome
What is thought to be the mechanism behind clonus?
Essentially it is a result of pronounced hyperreflexia. Clonus is caused by a self-sustaining, oscillating, monosynaptic stretch reflex.
What is the corneal reflex?
When the cornea is stimulated with a wisp of cotton, there is a reflexive blinking response in both eyes (a normal response)
What is dysarthria?
A disorder of speech articulation. Comprehension and speech content are not affected. There are several types of dysarthria that vary in the rate, volume, rhythm and sound of the patient’s speech
What are causes of dysarthria?
- Intoxication (e.g. alcohol, benzodiazepine)
- Drug toxicity (e.g. lithium, phenytoin)
- Cerebellar infarction
- Vertebral artery dissection
- Cerebellar mass lesion – tumour, abscess, AVM
- Multiple sclerosis
- HSV cerebellitis
- Hereditary cerebellar degeneration (Freidreich’s ataxia)
- Paraneoplastic cerebellar degeneration
What is flaccid dysarthria?
Speech sounds slurred/nasal
What is spastic dysarthria?
Speech sounding as if patient is trying to squeeze words out of pursed mouth
What is ataxic dysarthria?
Speech is uncordinated - range, timing, direction innacurate, rate is slow and may be explosive
What is Hypokinetic dysarthria?
Speech may sound monotonous or slow-paced
What is hyperkinetic dysarthria?
Involuntary disruption in sounds +/- movements
What might cause an ataxic dysarthria?
Cerebellar dysfunction
What can cause spastic dysathria?
UMN lesions
What is dysdiadochokinesia?
https://www.youtube.com/watch?v=2EZqnmxWyAY
Dysdiadochokinesis is difficulty in performing rapid alternating movements. The patient’s movements may be slow and/or clumsy.
What are causes of dysdiadochokinesia?
- Alcohol intoxication
- Drug toxicity – lithium, phenytoin, benzodiazepine
- Cerebellar infarction
- Vertebral artery dissection
- Cerebellar mass lesion – tumour, abscess, AVM
- Multiple sclerosis
- HSV cerebellitis
- Hereditary cerebellar degeneration (Freidreich’s ataxia)
- Paraneoplastic cerebellar degeneration
Why does dysdiadochokinesia occur?
Intermediate and lateral hemisphere dysfunction results in delays of motor initiation and movement termination at the end of movement (i.e. dysmetria). This, combined with abnormalities of movement force and acceleration, contribute to dysdiadochokinesia
What is essential tremor?
Essential tremor is a 4–12 Hz symmetric tremor of the upper limbs, with postural (seen in the outstretched arm) and/or kinetic (during movement) components. It may also affect the jaw, tongue, and head and neck muscles, leading to a characteristic ‘nodding yes’ or ‘shaking no’ tremor.
Why might you get a abnormal efferent corneal reflex in Bell’s Palsy?
Efferent corneal reflex defect (facial nerve)
Why might you get dry irritated eye in facial nerve palsy?
- Orbicularis oculi muscle weakness results in incomplete eye closure
- Lacrimal gland dysfunction
What are fasciculations?
Fasciculations are involuntary, nonrhythmic contractions of small muscle groups caused by spontaneous firing of motor units. They appear on the surface of the muscle as fine, rapid, flickering contractions, irregular in timing and location
What are causes of fasciulations?
Lower motor neuron sign
- Benign fasciculations
- Motor neuron disease (amyotrophic lateral sclerosis)
- Radiculopathy
- Depolarising paralytic agent – succinylcholine
- Cholinergic toxicity – organophosphate toxicity
- Funnel-web spider envenomation
- Thyrotoxicosis
- Poliomyelitis
- Spinal muscular atrophy
What is thought to be the cause of fasciculations in LMN disorders?
Denervation and reinnervation of muscle fibres secondary to lower motor neuron disease causes the spontaneous excitation of individual motor units.
How does cholinergic toxicity cause fasciculations?
Due to potentiation of acetylcholine at the neuromuscular junction
What is the afferent limb of the gag reflex?
Glossopharyngeal nerve (CNIX)
What is the efferent limb of the gag reflex?
Glossopharyngeal and Vagus nerve
What is an abnormal gag reflex?
Absence of stylopharyngeus muscle and superior pharyngeal muscle constriction following stimulation of the posterior tongue and/or oropharynx. Absence of the gag reflex can be unilateral or bilateral.
What can cause a loss of gag reflex?
- Normal variant
- Generalised CNS depression
- Glossopharyngeal nerve (CNIX) lesion
- Vagus nerve (CNX) lesion
- Lateral medullary syndrome (Wallenberg’s syndrome)
What is the glabellar tap sign?
Tapping the glabella (between the patient’s eyebrows) causes blinking, which typically ceases after several taps. Persistent blinking (i.e. more than 4 or 5 blinks) in response to glabellar tapping is abnormal (called Myerson’s sign).
What conditions can cause a positive glabellar tap sign?
- Clasically - Parkinson’s disease
- Alzheimer’s dementia
- Vascular dementia
- Frontotemporal dementia
- Lewy Body dementia
- Advanced HIV/AIDS dementia
What is global aphasia?
Global aphasia is a disturbance of speech with expressive and receptive components (i.e. a combination of Broca’s and Wernicke’s aphasia). Speech is nonfluent or nonexistent, and comprehension is impaired. Naming, repetition, reading and writing are all affected
What are causes of global aphasia?
- Cerebral infarction, MCA territory
- Cerebral haemorrhage
- Alzheimer’s disease
- Vascular dementia
- Mass lesion – tumour, abscess, AVM
- Primary progressive aphasia
What are features of global aphasia?
- All aspects of speech impaired
- Contralateral motor/sensory signs
- Contralateral hemianopia
What’s the most common cause of global aphasia?
MCA territory infarct
What is the grasp reflex?
The patient involuntarily grasps the examiner’s fingers when the examiner strokes the patient’s thenar eminence. The grasp reflex is a primitive reflex present in infancy, which normally disappears later in life
What are causes of a positive grasp reflex?
- Alzheimer’s dementia
- Vascular dementia
- Frontotemporal dementia
- Lewy body dementia (LBD)
- Advanced HIV/AIDS
Why is hand dominance important?
Hand dominance is clinically significant in the context of dominant cortical localising signs. The side of hand dominance correlates with the side of the dominant cerebral hemisphere and therefore has potential localising value.
What is hemineglect syndrome?
A disorder of conscious perception, characterised by a lack of awareness of the contralateral visual hemispace and contralateral body. The patient may be completely unaware of their own body or objects in the neglected space (i.e. anosognosia). The presence of hemineglect is typically evaluated with clock face drawing, search/cancellation and/or line bisection tests.
What is sensory neglect?
Patient ignores visual, tactile or auditory stimuli in the contralateral hemispace
What is motor neglect?
Patient performs fewer movements in the contralateral hemispace
What is conceptual neglect?
Patient’s internal representation of own body and/or external environment exhibits neglect