DIT review - Neurology 4 Flashcards
What is status epilepticus
Continous or recurring seizure that may result in brain injury; defined as > 5 min
Meissner corpuscle (type, location, effect)
♣ Rapidly adapting, superficial
♣ Dynamic, fine/light touch
♣ On hairless skin
Pacinian corpuscle (type, location, effect)
♣ Rapidly adapting, deep
♣ Vibration, pressure
♣ Deep skin layers, ligaments, joints
Merkel disc ((type, location, effect)
♣ Slowly adapting, superficial
♣ Deep static touch
♣ Fingertips, superficial skin
Ruffini corpuscle (type, location, effect)
♣ Slowly adapting, deep
♣ Pressure, slippage of objects along surface of skin
♣ Fingertips, joints, soles of feet
Flow of input through the cerebellum
Inputs (mossy fiber and climbing fibers) - cerebellar cortex - axons of purkinje fibers (always inhibitory signal) - deep nuclei of cerebellum - output targets (usually superior cerebellar peduncle - contralateral ventral lateral nucleus of the lateral thalamaus)
What are the deep nuclei of the cerebellum
- Lateral to medial - Don’t Eat Greasy Foods
- Dentate
- Emboliform
- Emboliform + Globose = Interposed
- Globose
- Fastigial
Functional units of the cerebellum and their corresponding deep nuclei
- Vestibulocerebellum
- Vermis + flocculonodular (most medial)
- Fastigial deep nucleus
- Spinocerebellum
- Vermis + paravermis
- Interposed deep nucleus
- Cerebrocerebellum
- Lateral hemisphere
- Dentate deep nucleus
What are the most common causes of essential, intention, and resting tremor?
Essential (with rest and movement) - genetic
Intention - cerebellar dysfunction
Resting - Parkinson’s
Describe the different between Ia and Ib afferent muscle fibers
Ia - afferent fiber from intrafusal fiber
Synapse directly on and activate alpha motor neurons in order to stimulate the extrafusal muscle corresponding to the intrafusal fiber (e.g. opposes the stretch sensed by intrafusal fiber)
Ib - afferent fiber from golgi tendon organ
Synapses on inhibitory interneuron in spinal cord - interneuron synapses on alpha motor neuron and inhibit them - leading to relaxation of extrafusal fiber
What is the presentation and cause of hemiballismus
- Sudden, wild flailing of half of body (1 arm +/- ipsilateral leg)
- Seen in lesion of contralateral subthalamic nucleus
Define athetosis and it’s cause
Slow, writhing movements, especially seen in the fingers
Due to lesion of basal ganglia (Huntington’s)
Define chorea and its cause
Sudden, jerky, purposeless movements
Seen in lesion of basal ganglia (e.g. Huntington’s)
Define dystonia
Sustained, involuntary muscle contractions
Define akathisia and its cause
- Dancing in place (voluntary) / Restlessness
- Compulsion to move
- Seen with neuroleptic use or in Parkinson’s
What disease presents with Lewy bodies and what make up Lewy bodies?
Intracellular eosinophillic inclusions of alpha-synuclein within neurons
Seen in Parkinsons and Lewy body dementia

What disease is MTPP exposure associated with?
Parkinsons
- MTPP converted to MPP via COMT
- MPP destroy dopaminergic neurons
Describe characteristic features of Parkinsons
- Due to loss of dopaminergic neurons
- Depigmentation of substantia nigra
- Lewy bodies (eosinophilic inclusions of alpha-synuclein) within neurons
- TRAPS
- Tremor (resting)
- Rigidity (cogwheel)
- Akinesia (or bradykinesia)
- Postural instability
- Staggering gait
Describe characteristic features of Huntington’s
THINK: C’s
CAG trinucleotide repeat
On chromosome 4
Occurs in 40s
Chorea
Cognitive decline (dementia)
Caudate atrophy (and putamen)
Increased DA, decreased GABA, decreased ACh
Identify the location of the following in the spinal cord:
Dorsal column
Spinothalamic tract
Corticospinal tract (lateral and anterior)

Describe the pathway of the dorsal column/medial lemniscus
- First order neurons (dorsal column) have cell bodies in dorsal root ganglion or cranial nerve ganglion and ascend ipsilaterally to the nucleus gracilis (lower body) or nucleus cuneatus (upper body) in the medulla
- In the medulla they synapse on second order neurons which then cross the midline
- Second order neurons (now called the medial lemniscus) ascend to the contralateral thalamus (VPL) where they synapse on 3rd order which ascend to the somatosensory cortex and synapse on 4th order

Describe pathways of spinothalamic tract
- Processes pain, temperature, and light touch (crude touch?)
- First order neurons have cell bodies in dorsal horn (of gray matter) and synapse on thermoreceptors and nociceptors in the skin
- First order nerves synapse on second order in the dorsal horn of the spinal cord, where the second order cross the midline at the anterior white commissure and ascend to the contralateral thalamus (VPL) when second order synapse on third order which ascend to somatosensory cortex and synapse on fourth order

Describe pathway of corticospinal tract
- UMN from motor cortex descend to pyramid in the medulla
- Axons cross to contralateral side in the caudal medulla and descend via lateral cortico-spinal tract
- Enter the spinal cord at lateral white column and travel to the anterior grey horn
- Synapse to LMN (alpha motor neuron) which then exits via ventral spinal root to innervate muscle

What part of the spinal cord is damaged in poliomyelitis
Anterior motor horn - LMN lesion with asymmetric weakness


