12/ Let’s return to one of the questions from the lead tweet.
Why do some people get brain freeze but not everyone?
While the answer isn’t entirely clear, it may have to do w/ predisposition to headaches in general, particularly migraines.
13/ In an observational study in adolescents, 55% of those with a history of migraines experienced brain freeze, versus only 39% of those without migraines.
15/ This apparent link b/w migraines and brain freeze actually makes physiologic sense.
Although migraines likely result from cortical spreading depressions and brain freeze from cerebral vasodilation, both involve trigeminal nerve system activation.
18/ Thankfully, brain freeze is transient and typically resolves within seconds to minutes.
Pressing your tongue to the roof of the mouth - which warms the mucosa and decreases stimulation of the trigeminal nerve/SPG - can help it resolve a bit faster.
19/ 🔑 Brain freeze results from cold-induced trigeminal and sphenopalatine ganglion stimulation
🔑 This induces cerebral vasodilation, which seems to be the source of headache
🔑 Predisposition to headaches (eg migraines) may account for why only some people get brain freeze
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Population studies have estimated that about 25-50% of the population experiences this phenomenon, though the prevalence seems to be much lower in Japanese cohorts.
1/ Why can multiple sclerosis symptoms worsen with heat exposure, something known as the Uhthoff phenomenon?
This question is especially relevant in the era of record-breaking heat waves and climate change.
#tweetorial #medtwitter
2/ In 1890, Wilhelm Uhthoff noted multiple sclerosis (MS) patients having a “marked deterioration of visual acuity during exercise" or after a hot bath, which ⬆️ body temperature.
1 patient lost vision just by walking vigorously in Uhthoff's clinic.
3/ The Uhthoff phenomenon is now recognized as exceedingly common in MS.
Up to 80% of patients experience ⬆️ neurological symptoms w/ even small body temp increases. These can include diminished physical (eg gait) and cognitive (eg mental fog) function.
1/THREAD
Has it ever occurred to you that Graves' disease presents a conundrum?
Graves' involves an autoimmune antibody that ACTIVATES a receptor, which is relatively unique in the landscape of human disease.
Let's unpack this fascinating mechanism.
#medtwitter #tweetorial
2/ Graves’ disease was first described by English physician Caleb Parry in 1786, when he noted an association between thyroid enlargement, tachyarrythmias, and exopthalmos in 8 patients.
Parry’s son posthumously published his description in 1825.