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Comments ...

 +0  (nbme18#10)

Renal damage from PKD can ultimately cause chronic renal insufficiency. This impairs the ability of the kidney to excrete phosphorus and reabsorb HCO3. Elevated phosphate levels in the blood triggers release of FGF-23 from bone, which lowers vitamin D production and decreases calcium absorption in the intestine. The resulting hypocalcemia and hyperphosphatemia will lead to an increase in the secretion of PTH.

 +0  (nbme18#36)

The patient has malignant hyperthermia, an adverse event associated with some anesthesia drugs (ie succinylcholine). The DOC for treating malignant hyperthermia is Dantrolene, which antagonizes the ryanodine receptor and results in decreased intracellular calcium.

 +4  (nbme23#37)

The posterior columns (Fasciculus cuneatus/Fasciculus gracilis) carry information to the brain regarding proprioception, vibration, discriminative touch and pressure. Physical exam findings suggest a lesion here (the spinothalamic tract carries pinprick/pain and temperature, and these were normal). Since the patient has abnormal findings in the lower extremities, and normal findings in the upper extremities, the answer is Fasciculus gracilis. This is because information from body areas below the level of T6 is carried by gracilis and information from body areas above the level of T6 is carried by cuneatus.

kai  kick Goals (gracilis) with your feet Cook and eat (cuneatus) with your hands
temmy  i remember gracilis is for legs by saying i have graciously long legs and they are inside while arms can spread out to remember their orientation on the spinal cord
jess123  I remember it as gracilis = grass so feet haha
link981  Just to add found on page 492 on FA 2018.
charcot_bouchard  Hey Temmy, I can spread my legs too :)
maxillarythirdmolar  I can't feel GRACIE's ~fine touch~ as she ~vibrates~ my balls.
cat5280  Could someone please explain why you were able to eliminate the spinocerebellar tracts?
drzed  Lmao I remember gracilis because of the gracilis muscle in the legs!
alexxxx30  cat5280...so spinocerebellar tract does 4 things to know 1. proprioception in the Romberg test 2. intention tremor if damaged 3. shin to knee test 4. dysdiadochokinesia (being able to rapidly pronate/supinate the upper extremity) yes the patient has proprioception issues, but the other symptom of vibration loss points us more to a fasciculus gracilis issue. If the patient had presented with proprioception and and intention tremor then we would think spinocerebellar
alexxxx30  adding to my comment^ I would commit these 4 things to memory as I have gotten several questions concerning this topic (there were 2 questions on this exam where spinocerebellar tracts are involved). Memorize them and it might get you 1-2 extra points!

Subcomments ...

Why is it 99% and not 95%? It asked for onset of disease at less than 9 years of age. I'm clearly missing something here

cbrodo  @fulminant_life because the mean age is 3.8 with a standard deviation of 1.8. An age of onset of 9 years is nearly 3 standard deviations above the mean. Therefore, since we know +/- 2 SD covers 95% of the bell curve, it must be higher than that. The only option higher than 95% is 99%. +8  
charcot_bouchard  Yes 9.2 was the upper limit for 99% CI. I picked 95 first because i thought 2.5% would be out of this range. But changed ans because it should be less than 2.5% because 9.2 is so close to 9. Also they are asking CLOSEST to which of the following? +  

submitted by sakbarh(6),

She has many cardiovascular risk factors and likely suffered a stroke of the basilar artery causing locked in syndrome. According to FA this can cause a lesion at the pons, medullar, or lower midbrain -- however anatomically the basilar artery runs right on top of the pons so proximity most likely makes it the right answer.

mousie  The Boards and Beyond video of SC strokes was really helpful at explaining this if you are a video kind of person! +  
yotsubato  What pushed me away from pons was "dysarthric speech" which implied she still could speak to some degree.... which made me pick medulla. +3  
mimi21  I think FA may be misleading. Primarily it will effect the Pons because that is where the majority of the Basilar Artery is located. and I guess it could effect the other locations? but everywhere I have looked Locked-in syndrome is an issue with the Pons. But someone please continue to clarify, cause I was a bit tripped up at first with this question +  
cbrodo  Although FA says it can be pons, medulla, or lower midbrain, "locked-in" syndrome generally arises from BL pons lesions. Another way you can rule out medulla and midbrain in this question is the ocular movement findings. Since the patient has impaired horizontal gaze BL, you can conclude that the Abducens nuclei are involved on both sides. The abducens nuclei are located in the pons. +15  
gh889  USMLE secrets also states that it is most commonly in the pons Bates states that locked-in syndrome preserves consciousness but these patients have limited speaking ability +