Where's the lesion?

Question 1

What spinal tracts does polio damage? What kind of paralysis does this cause?

Answer 1

Anterior horns, causes LMN lesions leading to flaccid paralysis

Question 2

What findings are seen in syringomyelia?

Answer 2

A cape-like, bilateral loss of pain and temp in upper extremities - results from a syrinx (CSF-filled cavity in the spinal cord) that expands and damages the anterior white commissure. Seen in 35% of Chiari malformations

Question 3

What conditions can lead to facial nerve palsy?

Answer 3

AIDS, Lyme disease, Sarcoidosis, Tumors, and Diabetes

ALexander Bell with STD

Question 4

What is a “blown pupil” suggestive of?

Answer 4

Impending ipsilateral brainstem compression

Question 5

Where relatively in the brainstem is the dysfunction for decorticate vs decerebrate posturing?

Answer 5

Decorticate posturing indicates slightly more superior brainstem dysfunction (decerebrate slightly more inferior)

Question 6

What are the likely causes of decreased consciousness in a patient with focal findings vs no focal findings?

Answer 6

Focal - structural causes (e.g. stroke, hemorrhage, tumor, abscess)
Focal signs absent - diffuse causes (e.g. metabolic, toxic, infectious, hypoxia)

Question 7

Where’s the lesion that causes locked in syndrome?

Answer 7

Basilar artery infarction - leads to damage to the pons

Question 8

What is damaged if there is a relative afferent pupillary defect?

Answer 8

Damage to the optic nerve of the eye that remains relatively dilated when light is shined in that eye. The affected eye will constrict consensually when light is shown into the “good” eye

Question 9

How do hydroxyamphetamine eye drops help distinguish a preganglionic (1st and 2nd order) lesion from a postganglionic (3rd order) lesion in sympathetic fibers (Horner syndrome)?

Answer 9

The pupil will fail to dilate if it’s a 3rd order lesion but will dilate if it’s preganglionic

Question 10

What does ptosis, dilated pupil (mydriasis) and ophthalmoplegia indicate (eye down and out)?

Answer 10

III nerve palsy

Note that CN III’s nucleus is in the midbrain

Question 11

How do CN III nerve palsy’s present differently when compression vs diabetes is the cause?

Answer 11

The parasympathetic fibers run on the outside and motor fibers on the inside of the nerve so compression causes ptosis and mydriasis initially followed by motor problems (eye down and out). DM affects the blood vessels within the nerve primarily damaging motor functions

Question 12

What does upbeating nystagmus indicate?

Answer 12

A lesion of the anterior cerebellar vermis and lower brainstem. Can also occur with drug intoxication and Wernicke’s encephalopathy

Question 13

What does downbeating nystagmus indicate?

Answer 13

Disorders of craniocervical junction (Chiari malformation). spinocerebellar degeneration, MS, familial periodic ataxia, and drug intoxication

Question 14

In vestibular nystagmus, what direction is the fast phase?

Answer 14

Away from the lesion

Question 15

What lesion is responsible for conjugate gaze deviation?

Answer 15

The frontal eye field in the frontal lobe, eyes deviate towards the side with the lesion

Question 16

What motor symptoms do lesions to the base of the pons cause?

Answer 16

Weakness of the ipsilateral face and contralateral arm and leg (“crossed signs”), because descending motor fibers to the face have already crossed at that level but not the body

Question 17

What neurons are damaged in spastic vs atonic bladder?

Answer 17

UMN in spastic (e.g. frontal lobe, pons, suprasacral spinal cord) - causes urge incontinence; LMN in atonic bladder (e.g. conus mdullaris, cauda equina, sacral plexus, peripheral nerve) - causes overflow incontinence

Question 18

Damage to where causes ballism or hemiballismus?

Answer 18

Contralateral lesion of the caudate, putamen, or subthalamic nucleus. Stroke is the most common cause, although hyperglycemia may also be a cause

Question 19

What artery supplies the anterior horns, the STT, and the corticospinal tracts of the spinal cord?

Answer 19

The Anterior spinal artery (cephalad portion from the vertebral arteries and caudally from the aorta via the artery of Adamkiewicz). Anterior spinal artery syndrome is due to a stroke affected motor and pain and temp function below the lesion (posterior column function is usually spared)

Question 20

What is Meralgia paresthetica?

Answer 20

Caused by entrapment of the lateral femoral cutaneous nerve near the inguinal ligament. Causes burning sensation and variable loss of sensation over the anterolateral thigh

Question 21

What are features of peroneal neuropathy?

Answer 21

Due to entrapment of the peroneal nerve between the neck of the fibula and the insertion of the peroneus longus muscle. Presents with foot drop with minimal sensory complaints

Question 22

A lesion of what part the brain can cause apraxia (inability to perform a learned motor task)?

Answer 22

The dominant frontal or parietal lobe

Question 23

What does sudden onset of hypophonia (soft speech suggest)?

Answer 23

Subcortical (usually thalamic) lesion

Question 24

Disease in what part the brain leads to intention/kinetic tremors?

Answer 24

Cerebellum

Question 25

Damage to what nerve leads to clawhand/benediction sign (impaired extension of digits 4 and 5)?

Answer 25

Ulnar nerve (due to weakness in the lumbricals causing malpositioning of the extensor sheaths

Question 26

What ocular nerve is most likely to be damaged with facial trauma?

Answer 26

CN IV because it extends farthest into the orbit

Question 27

What area of the CNS is damaged with ocular bobbing (rapid downward deviation of eyes followed by slower conjugate gaze back up)?

Answer 27

Pontine damage

Question 28

Damage to the STT causes loss of pain and temp sensation at what level relative to the lesion?

Answer 28

1-2 segments below the lesion because second order neurons ascend 1-2 levels before crossing the anterior white commissure