Lectures Flashcards
Examples of disorders affecting brainstem
Tumours
Inflammatory disorders e.g. MS
Metabolic e.g. central pontine myelonecrosis (Na+)
Trauma
Spontaneous aneurysm e.g. AVM, aneurysm
Infarction e.g. vertebral artery dissection
Infection e.g. cerebellar abscess from ear
Criteria from brainstem death
Pupils Corneal reflex Caloric vestibular reflex Cough reflex Gag reflex Respirations Response to pain
Different types of sensory fibres (large and small)
Aα and Aβ (large myelinated fibres)
Aδ and C (thin, small fibres)
Difference between Aα and Aβ (large myelinated) sensory fibres
Αα are transmitting signals regarding proprioception and Aβ about light touch, pressure and vibration.
Difference and similarity between Aδ and C fibers small, thin sensory fibres
Aδ are myelinated and C unmyelinated
Both transmit signals regarding pain
Additionally, Aδ signals are about cold sensation and C signals are about warm sensation.
What is result of demyelinating neuropathies
Myelin is destroyed
Leads to slower conduction velocities
What is difference between mononeuropathy and polyneuropathy
Mononeuropathy = problem with one nerve Polyneuropathy = problem with multiple nerves
Examples of common mononeuropathies
Carpal tunnel syndrome
Ulnar neuropathy
Peroneal neuropathy
Cranial mononeuropathies e.g. III or VII cranial nerve palsy
What nerve is compressed in carpal tunnel syndrome
Median nerve
Cause of ulnar neuropathy
Entrapment at the cubital tunnel
Cause of peroneal neuropathy
Entrapment at the fibular head
Cause of cranial neuropathies such as III or VII cranial nerve palsy
Idiopathic
Immune mediated
Ischaemic
Subtypes of large fibre neuropathies
Axonal
Demyelinating
Define peripheral neuropathy
Any disorder of the peripheral nervous system
Can be acute or chronic
Types of causes of chronic demyelinating neuropathies
Genetic
Inflammatory
What is CIDP
Chronic inflammatory demyelinating polyneuropathy (CIDP)
A rare neurological disorder in which there is inflammation of nerve roots and peripheral nerves and destruction of the fatty protective covering (myelin sheath) over the nerves
What is ataxia
Poor balance
Causes of ataxia
Sensory - loss of proprioception
OR
Cerebellar
In sensory ataxia, what makes it worse
Eyes closed or when dark
Motor symptoms of peripheral neuropathies
Muscle cramps Weakness Fasciculations - muscle twitches Atrophy High arched feet (pes cavus)
3 categories of axonal peripheral neuropathies
Symmetrical sensorimotor (or sensory neuropathies) Sensory gangliopathies (or asymmetrical sensory) Asymmetrical sensorimotor neuropathies (or mononeuritis multiplex)
What is the most common type of peripheral neuropathy
Symmetrical sensori-motor PNs
Presentation of symmetrical sensori-motor peripheral neuropathies
Initially sensory symptoms affecting the toes and fingers (Length-dependent pattern) and eventually motor symptoms again in a length dependent pattern.
Long fibres are affected first
Example of asymmetrical sensory neuropathy
Sensory gangliopathy
In sensory gangliopathy, what structure is affected
Dorsal root ganglia
Characteristics of Sensory gangliopathy (asymmetrical sensory PN)
Purely sensory and characteristically presents with patch distribution of symptoms.
Dorsal root ganglia are affected.
Relatively uncommon overall, but common as a paraneoplastic manifestation or in the context of Sjogren’s disease and gluten sensitivity
What is Sjogren’s disease
A condition that mainly affects the glands that produce saliva and tears, causing a dry mouth and/or eyes
Example of asymmetrical sensorimotor PN
Mononeuritis multiplex
Occurs in the context of vasculitis
Characteristics of asymmetrical sensorimotor PN
Multiple nerve involvement
Can randomly affect any nerve without a specific pattern
Very common but painful and occurs in the context of Vasculitis
Diagnostic approach to PN (first steps)
History
Clinical examination
Neurophysiological examination i.e. NCS/QST
Diagnostic approach to PN: Clinical examinations done
Reduced or absent tendon reflexes
Sensory deficit
Weakness - muscle atrophies
Diagnostic approach to PN: Neurophysiological examinations
Nerve conduction studies - determine type of neuropathy
How would you diagnose a demyelinating PN in nerve conduction study
Reduced conduction velocities and/or conduction block in sensory and motor nerves with minimal or no abnormalities in the SNAP and CMAPs
How would you diagnose mononeuritis multiplex PN in nerve conduction study
SNAPs and CMAPs of affected nerves are reduced
Asymmetrical
How would you diagnose SMA (Spinal Muscular Atrophy) PN in nerve conduction study
Symmetrical type of sensorimotor pn
Reduced SNAPs in beginning and eventually CMAPs
Nerve conduction study: difference between demyelinating and axonal
Demyelinating = slow conduction velocities Axonal = reduced amplitudes of the potentials
Causes of axonal PN
Associated with systemic diseases
Inflammatory – immune mediated (mainly acute)
Infectious (i.e. hepatitis, HIV, Lyme)
Ischemic (i.e. vasculitis)
Metabolic (i.e. Fabry’s, porphyria)
Hereditary (CMT, HLPP)
Toxins (pharmaceuticals, environmental toxins, B6)
Systemic diseases associated with axonal PN
Diabetes Vitamin deficiency (commonly B12) Gluten sensitivity / coeliac disease Chronic renal disease Excessive alcohol drinking Hypothyroidism Amyloidosis Connective tissue disease Paraproteinemia Paraneoplastic Critical illness polyneuropathy
What is meant by chronic idioapthic axonal polyneuropathy
Develops over at least 6 months (chronic)
No aetiology can be identified despite extensive and appropriate investigations (Idiopathic)
Axons are affected, most commonly in proportion to their length (Axonal)
Examples of immune mediated chronic demyelinating neuropathy
CIDP (chronic inflammatory demyelinating polyneuropathy)
Multifocal motor neuropathy (MMN)
Examples of genetic chronic demyelinating neuropathy
Charcot Marie Tooth disease
Hereditary sensory and autonomic neuropathies
Example of an acute polyneuropathy
Guillain Barre syndrome
What is Guillain Barre syndrome
Autoimmune disorder in which the immune system attacks healthy nerve cells in your peripheral nervous system (PNS). This leads to weakness, numbness, and tingling, and can eventually cause paralysis.
Clinical presentation of Guillain Barre syndrome
Progressive ascending limb weakness (usually symmetrical) that peaks at 4 weeks, usually lost reflexes, some paraesthesia (‘walking on rubber’). Little to no muscle wasting.
Infection (e.g. GI) may precede the disease (campylobacter)
What type of neuropathy is Guillain Barre syndrome
Demyelination and axonal degradation -> progressive ascending neuropathy
What is Miller Fisher syndrome
Variant of Guillain Barre syndrome that affects cranial nerves of the eye muscles (opthalmoplegia and ataxia)
Aetiology of Guillain Barre syndrome
Most have preceding infection, usually of respiratory and GI. Potentially antibodies to infection also attack peripheral nerves. Usually caused by campylobacter jejuni.
Can be CMV
Pathophysiology of Guillain Barre syndrome
Demyelination and axonal degeneration -> acute, ascending and progressive neuropathy
Probably antibodies from the infection succumb to molecular mimicry and attack myelination
Diagnosis of Guillain Barre syndrome
Clinical. Antibody screen. Nerve conduction studies. CSF: raised protein level with a normal white cell count. Monitor FVC for respiratory involvement
Treatment of Guillain Barre syndrome
IV immunoglobulin.
Plasma exchange possible.
Ventilate if necessary.
Complications of Guillain Barre syndrome
Life threatening respiratory failure
Lower Motor Neurone lesion (sequelae)
Treatment of neuropathy
Aim to identify any reversible cause and stop progression if possible Symptomatic treatment: Pain Cramps (Quinine) Balance (physiotherapy/walking aids)
Treatment of pain symptoms in neuropathy (medical)
Amitryptilline
Gabapentin
Pregabalin
A 72 year old patient with a 15 year history of diabetes complains of burning sensation and tingling in his both feet for 3 years. Over the last 12 months the symptoms have progressed up to the level of the knees.
On examination he has reduced tendon reflexes in the upper limbs and the knees and absent tendon reflexes in the ankles. He has reduced vibration sensation up to the knees.
What is the most likely diagnosis?
Peripheral neuropathy of axonal type (length dependent)
Diabetes Burning sensation and tingling Reduced tendon reflexes Absent tendon reflexes in the ankles Reduced vibration sensation up to the knees
A 32 year old woman with a 5 day history of progressive weakness and tingling which started from the lower limbs but now has affected the upper limbs too.
On examination she has absent tendon reflexes.
Her medical history is unremarkable, however she reports D&V about 3 weeks ago.
What is the most likely diagnosis?
Acute polyneuropathy
Guillain Barre syndrome
5 day
started from the lower limbs
absent tendon reflexes
D and V about 3 weeks ago
A 52 year old man reports patchy sensory loss and complains of poor balance, symptoms which are getting gradually worse.
Ten year earlier he was diagnosed with coeliac disease.
On examination he has mild sensory ataxia, reduced reflexes and patchy loss of pinprick and vibration sensation.
What is the most likely diagnosis?
Sensory ganglionopathy
Patchy sensory loss
Poor balance
Coeliac disease
