Nerve diseases Flashcards
What is peripheral neuropathy + name types of peripheral neuropathy
Damage of peripheral nerves
Can affect one nerve (mononeuropathy), two or more nerves in different areas (multiple mononeuropathy) or many nerves (polyneuropathy)
Causes of peripheral neuropathy (8)
Heriditary Diabetes Alcoholism Infectious diseases - lyme, HIV Certain medications - esp chemo Tumour compression Paraneoplastic - body's immune response as a result of the cancer Autoimmune diseases - Guillain barre syndrome, chronic inflammatory demyelinating polyneuropathy
Pathophysiology of Guillain barre syndrome (acute inflammatory demyelinating polyneuropathy)
-proposed mechanism
Acute inflammatory demyelinating polyneuropathy (i.e. a peripheral neuropathy affecting many nerves)
Thought to maybe be an AUTOIMMUNE ATTACK OF MYELIN sheath of peripheral sensory and motor nerves –> decreased propagation of electrical impulses –> motor weakness/flaccid paralysis
When immune reaction stops, repair and remyelination promptly begin, which correlate with a quick recovery from the flaccid paralysis
Risk factor of Guillain barre syndrome
Preceding viral/bacterial infection, esp gastroenteritis or URTI
Clinical features of Guillain barre syndrome
- which symptoms are seen first
- sensory (1)
- motor (8)
(hint: bilateral, FLACCID, ascending weakness of limbs peaking in <4 weeks)
Paraesthesia - PRECEDES WEAKNESS
Back and leg pain - PRECEDES WEAKNESS
Muscle weakness
- usually hands/feet first BEFORE spreading to arms/legs
- facial weakness
- oropharyngeal weakness –> dysphagia
- extraocular muscle weakness –> diplopia
- ptosis
- dysarthria
- dyspnoea/resp distress
Absent reflexes/hyporeflexia
FLACCID PARALYSIS (late symptom)
Investigations of Guillain barre syndrome + their findings (2)
Nerve conduction studies - shows slowing of conduction velocities
LP - shows increased CSF protein but NORMAL CELL COUNT
Where do symptoms of peripheral neuropathies usually start
Distally in feet and hands and spread up legs/arms
UMN lesion signs (4) + 2 not seen
Weakness NO WASTING Increased tone (spasticity) Brisk/exaggerated reflexes NO FASICULATIONS Babinski +ve (extensor plantar)
LMN lesion signs (6)
Weakness Wasting Decreased tone (flaccidity) Decreased reflexes Fasciculations Babinski -ve (flexor plantar)
Symptoms (3) /signs (10) of motor neurone disease (amyotrophic lateral sclerosis)
BOTH UMN (4) + LMN SIGNS (6)
Symptoms:
Dyspnoea
Dysphagia
Dysarthria
Motor neurone disease is a disorder of what horn
Anterior (Ventral) horn
Muscle weakness usually begins in the (1) in motor neurone disease but sometimes may begin in other places - name these (2)
Limb weakness
May also begin in bulbar muscles (Swallowing + speech) or resp muscles
What initial presentation of motor neurone disease is more aggressive - limb weakness or bulbar weakness
Bulbar weakness
Investigations/diagnosis (2) of motor neurone disease
Clinical diagnosis is 1st line - a thorough history and examination
Electromyography (EMG) - shows diffuse, ongoing, chronic denervation
Treatment of motor neurone disease
- supportive
- medical
Supportive/palliative care
- mechanical ventilation
- physio
- speech and language therapy
- feeding tube
Riluzole - prolongs survival as it’s a glutamate antagonist (degeneration in ALS is caused by excitatory glutamate neurotransmitter so if you block that then can slow degeneration)
How does riluzole help in motor neurone disease
prolongs survival as it’s a glutamate antagonist (degeneration in ALS is caused by excitatory glutamate neurotransmitter so if you block that then can slow degeneration)
What type of lesion is a nerve root disease (Radiculopathy)
LMN lesion
Motor (6) /sensory (1) /autonomic (2) signs of nerve root disease (think what lesion nerve root means)
LMN signs (6) -Myotomal wasting + weakness of the nerve root damaged
Sensory signs:
-dermatomal sensory loss (Area of skin innervated by that nerve loses sensation)
Autonomic signs:
-may get bladder/bowel dysfunction
Investigation of nerve diseases (e.g. radiculopathies, peripheral nerve lesion, peripheral neuropathies) (5)
LP + CSF analysis Nerve conduction studies Nerve biopsy Routine bloods Genetic analysis
Individual peripheral nerve lesion causes (2)
Lesion is either:
- compressive neuropathy
- Vasculitic neuropathy (blood supply to the peripheral nerve damaged)
Signs of individual peripheral nerve lesion (3)
Wasting
Weakness
of innervated muscle
Specific sensory loss
What is generalised peripheral neuropathy
Damage to peripheral nerves affecting motor and sensory and maybe autonomic function
Most common cause of chronic peripheral neuropathy
Diabetes
Symptoms/signs of peripheral neuropathies (think Guillain barre)
- sensory (4)
- motor (3)
- autonomic (4)
Sensory: Paraesthesia Numbness Burning/stabbing pain Sensory ataxia - loss of balance and co-ordination when eyes closed
Motor:
muscle weakness, especially in feet
Muscle fasiculations
Muscle wasting
Autonomic (DEPENDS ON WHERE THE AUTONOMIC FIBRES THAT ARE DAMAGED SUPPLY): Nausea/vomiting Constipation or diarrhoea Urinary retention Bowel incontinence
Define radiculopathy
DISEASE OF SPINAL NERVE ROOTS
= compression of nerve roots leading to DERMATOMAL + MYOTOMAL DEFICITS
Symptoms/signs of a nerve root lesion, e.g. L4 nerve root lesion (4) [think LMN signs)
Pain down ipsilateral leg
Numbness in L4 dermatome
Weakness in ankle dorsiflexion
Reduced knee jerk
Cauda equina syndrome is a disease of which nerve roots
L2-Cc1
Symptoms/signs of caudal equina syndrome (think clinical triad)
Bilateral sciatica – pain down both legs
Saddle anaesthesia – numbness around bottom
Urinary dysfunction
Investigation of cauda equina syndrome
MRI
Treatment of cauda equina syndrome
Emergency lumbar discectomy
What is more affected - sensory or motor function - in diabetic retinopathy
Sensory
Symptoms/signs seen in Guillain barre not seen in myasthenia gravis (3)
Absent reflexes/hyporeflexia
Sensory loss/paraesthesia
Muscle wasting
Signs seen in myasthenia gravis that are not seen in motor neurone disease (4)
Ptosis
Diplopia
Opthalmoplegia - paralysis of extraocular muscles
Muscle fatiguability throughout the day
