Syndromes, Cases, and Vision Flashcards
(38 cards)
Hemicord Lesion/Brown-Sequard:
- IPSILATERAL DCML & Motor Loss
- CONTRALATERAL ALS (pain & temp) loss
- Zone of Lessure - sprouting above and below lesion
- EVERYTHING IPSILATERAL EXCEPT ALS**
Transverse Cord Lesion:
- Complete lesion
- Everything below the lesion does not work
- No sensory going up, No motor coming down
Central Cord: (Small))
- Affects anterior commissure (decussation site of ALS)
- Small: Bilateral suspended sensory loss pain & temp
Central Cord: (Large)
- Affects anterior commissure (decussation site of ALS)
- Large: More corticospinal involvement & DCML
- *ANAL WINK**
Posterior Cord
- Loss of DCML
- Also ⅓ of your Blood supply is found here can be affected
Anterior Cord
- Does Not affect DCML
- AFFECTS ALS bilaterally
- Hits some corticospinal tracts
- ⅔ of blood supply is here can be affected
Case 1: A 15-year-old high school wrestler was found lying supine on the mat after sustaining a hyperextension injury to his neck while drilling during practice, complaining of numbness, tingling, and a burning sensation in all 4 extremities. When the ambulance arrived, the patient was still complaining of numbness and tingling in all 4 extremities and was notably weak in motor function, especially in the upper extremities
Central Cord Syndrome
- Paralysis/Muscle weakness (especially the arms)
- Painful sensations (burning, tingling, dull ache)
Case 2: A 22 year-old snow skiing daredevil sustained an SCI while competing last weekend. He presents to your clinic with decreased ability to discriminate between hot and cold, and noticeable strength deficits throughout. His proprioception and ability to sense light touch are intact.
Anterior Cord Syndrome
- ALS and motor symptoms
- Other impaired sensations: Crude touch, Pain
Case 3: A 60 year-old male presents to your clinic with decreased pain sensation in his LLE and decreased proprioception in his RLE. If you suspect a Brown-Sequard lesion, which LE would you expect to be weak? (MVA)
Right LE
- DCML and motor pathways are affected on the same side
- ALS affected on other side
Eyes & Retina
Light enters lens & forms image on Retina (inverted/reversed)
Visual Field
Inferior VF → upper retina
Superior VF → lower retina
Right VF → left retina
Left VF → right retina
Fovea
Central Fixation Point in each eye
- Looks like a “V” (highest point of visual acuity)
- Surrounded by Macula
Optic Disk
Formed by axons leaving retina and entering optic nerve
- NO PHOTORECEPTORS
- BLIND SPOT: 15* laterally & slightly inferior to central fixation point
Outer/Back (layers of the retina)
- Contains Photoreceptors
- Rods: Good for low light, no color seen
- Cones: In fovea & macula (High resolution, COLOR)
Bipolar Cells/Middle (layers of the retina)
-Receives input from photoreceptors & sends to ganglion cell layer
Ganglion Cells/Innermost (layers of the retina)
Parasol Cells: LARGE cell bodies & diameter
-GROSS MVMT/STIMULI
-Project to MAGNO layer of lateral geniculate nucleus (LGN)
Midget Cells: SMALL cell bodies & diameter
-FINE VISUAL DETAILS & COLORS
-Project to PARVO cell layers of LGN
Optic Nerve
- Input from retinal ganglion cells axon
- Exit in Optic Canal
- Enter visual field of R. eye on R. Optic Nerve
Optic Chiasm
- Where fibers cross (medial and nasal fibers)
- If damaged: TUNNEL VISION
Optic Tract
- Each carries info from IPSILATERAL retina of each eye
- R. tract = info from L. visual field
- L. Tract = Info from R. visual field
- Damaged: Loss of vision in CONTRALATERAL FIELD
Lateral Geniculate Nucleus (LGN):
-Carries info from different eyes by same hemiretina
6 Layers
-Parvocellular Layer: receives info from midget cells
-Magnocellular Layer: receives info from parasol cells
Extrageniculate Pathways
- A small number of fibers bypass the LGN to the Superior and Pretectal Areas
- These fibers form the extrageniculate pathways
Optic Radiations
- Axons leaving LGN go to the primary visual cortex (PVC)
- These fibers pass through parietal and temporal lobes
- Lesion = Homonymous CONTRALATERAL visual field loss
- Ex: R. Optic Radiation carry info from L. side
Inferior Fibers (Meyers Loop)
- Arch forward to TEMPORAL LOBE from LGN —>INFERIOR BANK of Calcarine Fissure
- Carry info from inferior retina (superior VF)
- Damage = PIE in the SKY
Superior Fibers
- Pass under PARIETAL LOBE → SUPERIOR BANK of Calcarine Fissure
- Carry info from Sup. Retina (inferior VF)
- Damage = PIE on Floor
