Recent study links marijuana use to structural brain changes

 

 

Post  prepared by Amanda Baker, Drexel University College of Medicine Class of 2014

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A study recently published in the Journal of Neuroscience by Harvard researchers have linked casual marijuana use to structural changes in distinct areas of the brain.

These areas, the nucleus accumbens and amygdala, and are largely involved in recognition of reward, motivation, fear, and memory.  In this study, the brain scans of 20 young adult casual marijuana users were compared to those of 20 young adult non-users.

While the results clearly demonstrated significant structural differences between the two groups, the structural changes have not been correlated with consequences in mental or physical functioning.  In other words, researchers aren’t entirely sure of the impact of these brain changes.

 

Casual marijuana use may damage your brain

The debate regarding the use of marijuana medically and recreationally is ongoing in the United States.

Although the Drug Enforcement Administration(DEA) categorizes this drug as Schedule I, “with currently no accepted medical use and a high potential for abuse”, many argue that there is, in fact, much benefit to medical marijuana, especially in comparison to other sedating pain medications.

This is reflected in 21 state laws which have legalized medical marijuana to varying degrees.

Last summer, Dr. Sanjay Gupta completed a documentary “Weed” highlighting the benefit of medical marijuana:

However, some states such as Washington and Colorado, have gone one step further by legalizing marijuana for both recreational and medical use.

Given the ongoing research on the effects of marijuana, perhaps this new study will call into question continued legalization of the most widely used recreational drug in America.

 

Click here to find out more.

 

Memory misplaced

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Post written by Dr. Farida A. Malik , PGY3 Medical Resident, Monmouth Medical Center

Case Summary

This 69 year old lady had a remote history of breast cancer, hypertension and hypothyroidism.  She was brought to the Emergency Room by her husband because of abrupt onset confusion after waking up that morning. She was disoriented and was noted to ask the same questions over and over again. She had no difficulty walking, talking or dressing herself. She denied having headache or visual problems. There was no history of head trauma, seizures or any prior similar episodes.

When she was seen in the in the ER she knew her name and recognized her husband.  She was able to follow simple commands.  She had no recollection of events since morning or the day before. She repeatedly asked how she got to the hospital, despite being told several times that her husband brought her. Neurological examination otherwise was unremarkable.

CT scan of head, MRI of the brain and EEG were all normal.

She was diagnosed with TRANSIENT GLOBAL AMNESIA.

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The family was reassured about the benign nature of the condition and she was discharged home the next day still with memory lag.

Discussion

Transient global amnesia (TGA) is a clinical syndrome of reversible anterograde amnesia accompanied by repetitive questioning that occurs in middle-aged and elderly individuals.

The incidence of TGA is 5.2 to 10 per 100,000 per year overall, but 23.5 to 32 per 100,000 per year in adults aged 50 and over.

During a TGA episode recall of recent events simply vanishes. One may also draw a blank when asked to remember things that happened a day, a month or even a year ago.  Unlike “soap opera amnesia” (Jason Bourne) affected patients do remember who they are and recognize the people they know well.  But that doesn’t make their memory loss less any less disturbing.

Fortunately, episodes are usually short-lived, recover spontaneously, and are unlikely to recur.

The precise cause of TGA is unknown.  Atherosclerotic risk factors (eg. hypertension, diabetes, hypercholesterolemia) are not associated with TGA.
However there may be a link between TGA and history of migraines.

The primary site of neurologic functional disturbance is the medial temporal lobe and hippocampus.
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The pathogenesis of this transient disruption is unknown. Current theories include arterial ischemia, venous congestion, and migraine, but no theory explains all of the clinical features.

The diagnosis is made by the following signs and symptoms:

  • Sudden onset of memory loss, verified by a witness
  • Retention of personal identity despite memory loss
  • Normal cognition, such as the ability to recognize and name familiar objects and follow simple directions
  • Absence of signs indicating damage to a particular area of the brain, such as limb paralysis, involuntary movement or impaired word recognition
  • Duration of no more than 24 hours
  • Gradual return of memory
  • No evidence of seizures during the period of amnesia
  • No history of active epilepsy or recent head injury

Some common triggers identified are:

  • Sudden immersion in cold or hot water
  • Strenuous physical activity
  • Sexual intercourse
  • Medical procedures, such as angiography or endoscopy
  • Mild head trauma
  • Acute emotional distress, as might be provoked by bad news, conflict or overwork

There are no confirmatory diagnostic tests. The initial evaluation and management of patients with TGA focuses on excluding other diagnoses and should include the following:

  • If the patient is symptomatic on presentation, the patient should be observed in the hospital until the amnesia resolves.
  • Diagnostic testing includes oxygenation status, serum electrolytes, glucose, and a toxicology screen.

The need for further testing varies depending on the circumstances, such as how typical the event is for TGA, the presence of vascular risk factors, and whether the ictus was observed. Patients with recurrent or brief episodes, or activity suggesting motor automatism should be evaluated with EEG for possible epilepsy. A neuroimaging study may be performed in all patients, preferably a brain MRI with DWI, to exclude acute ischemia, head trauma, and other causes.

Treatment is not required for TGA. The condition usually does not recur, and the patient does not need to be restricted from driving unless events are recurrent.

There is no increased risk of mortality, epilepsy, or stroke following TGA as compared with age-matched controls.

Acute Back Pain, What Not To Do!

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70-80% adults have experienced acute back pain, almost 30% seek medical attention, and this problem is one of the commonest reasons for a doctors’ office visit.

Most cases are caused by sprains or tears in one of the numerous muscles or ligaments in the back triggered by twisting or lifting something heavy.

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These “soft tissue” injuries will usually improve on their own within a few weeks with anti-inflammatory medications and physical therapy.

However a recent study showed that more and more such patients are getting unnecessary imaging studies right away leading to surgeries and other invasive procedures that they don’t need.

Possible reasons cited for the necessary procedures include patient expectations and financial incentives for doctors.

flag_status_redDoctors shouldn’t immediately order an MRI or CT scan to determine the cause of back pain if a patient doesn’t have any red flags such as tingling in the legs — a sign of a nerve problem such as spinal stenosis — or a previous history of cancer.

Otherwise, imaging studies ordered for nonspecific back pain may reveal incidental disk problems, the result of aging, and not the cause of the symptoms.

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This will then often lead to unnecessary and unproven interventional pain management procedures.

Most back pain patients simply need to be told that their pain will improve with antiinflammatory medications, physical therapy, massage therapy, and/or supervised exercise programs.

However, in the words of Dr. John Mafi, one of the study’s authors, “it takes longer to sit and reassure patients that their pain will likely resolve on its own than it does to order an MRI.”

Correct clinical diagnosis of dizziness in the ER could save $$ billions

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We have already blogged about the danger of escalating health costs in the USA.

The cost of emergency room visits for severe dizziness has grown exponentially in recent years, topping $3.9 billion in 2011 and projected to reach $4.4 billion by 2015.

Investigators from Johns Hopkins estimate that half a billion a year could be saved immediately if emergency room physicians stopped the routine and excessive use of head CT scans to search for stroke in dizzy patients, and instead used simple bedside physical exams to identify the small group of patients that truly needs imaging.

Click here to find out more about the Johns Hopkins study.

Click here to find out more about the hidden dangers of unnecessary CT scans.

Once they understand how inner ear disease can cause vertigo and nystagmus, any physician can use our simple clinical scheme to distinguish inner ear problems from more serious and rarer central causes like stroke in dizzy patients.  Click here to find out how.

A ripping yarn – a tale of cervical artery dissection

Case Summary:
This 46-year-old woman was healthy except for a history of occasional migraine headaches and cigarette smoking. On the day of admission she had fallen down a short flight of steps carrying a heavy box. About 2 hrs later she complained of some neck pain.  Then later that evening developed abrupt onset left sided weakness. She arrived at the emergency room within 1.5 hrs of the onset of weakness. On examination, she was alert, but she had a right gaze deviation (she wouldn’t look to the left side) and the left side was completely paralyzed. She had a normal brain CT scan.

The stroke team was notified, and she was given intravenous thrombolytic (“clot busting”) drug therapy within 1/2 hr of her arrival at the hospital and 2 hrs since the onset of her symptoms.

Carotid ultrasound subsequently showed no flow in the right internal carotid artery, and carotid arteriography subsequently showed near occlusion of the artery from an arterial dissection (see image below, red arrow):

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What is cervical artery dissection?

Cervical artery dissection is caused by bleeding inside the wall one of the major arteries in the neck.

This process is thought to be triggered by local injury to the inside layer of the vessel wall.

Cervical artery dissections occur from blunt trauma:

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Cervical artery dissection can also occur after minor trauma, particularly in someone with a genetic predisposition:

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What diseases predispose to arterial dissection?

There are some specific syndromes such as Marfan syndrome, Pseudoxanthoma elasticum and Ehlers- Danlos syndrome type IV that are associated with a weakness in the arterial wall making an arterial dissection more likely:

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In other cases, the specific cause of arterial weakness is unknown, but there is ongoing research to try to identify genetic links.

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What happens after a cervical artery dissection?

Symptoms can be caused from the damaged arterial wall itself (local symptoms) and some affected patients will later develop strokes.

Local symptoms include neck pain, unusual headache and/or Horner’s syndrome.

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L Horner’s syndrome (small pupil and drooping eyelid) caused by damage to the sympathetic nerve fibers in the arterial wall from carotid dissection. Click here to find out more about Horner’s syndrome and other causes of unequal pupils.

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What about stroke?

Stroke symptoms only occur in 25-30% dissections and can occur several days after the neck trauma and/or onset of local symptoms.

The arterial dissection narrows the space inside the blood vessel (the lumen), so less blood flow gets to the brain:

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A carotid artery dissection with blood clot inside the arterial wall (left) leading to narrowing of the vessel lumen and less blood flow (right).

Cervical arterial dissections can also cause stroke when pieces of blood clot break off and move with the blood flow only to block small arteries further inside the brain (cerebral thromboembolism), or if the dissection tracks across (and blocks off) an arterial branch (see below):

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How is arterial dissection diagnosed?

Magnetic resonance imaging is probably the easiest way to make the diagnosis:

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MR angiogram (left) showing tapered occlusion of the left internal carotid (white arrow) from dissection. Fat suppressed T1 weighted MR axial image through the dissected cervical artery (right) showing bright blood within it’s wall (black arrow) from dissection.

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How is it treated?

In most cases the arterial dissection ultimately heals on its own without any surgical intervention.  There has been some controversy surrounding the use of anticoagulant vs anti-platelet drugs for stroke prevention after cervical artery dissection, but most current data favors the use of the anti-platelet drug aspirin:

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Of course, for patients presenting with symptoms of acute stroke, throbolytic therapy is also an option, and can improve outcome without increased risk in stroke from dissection:

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Click here to find out more about cervical artery and dissection and stroke.

Click here to find out what to do if you think your having a stroke.

Click here to find out more the certified stroke center at Monmouth Medical Center.

Shouldn’t I have a brain MRI, doctor?

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Migraine is extremely common, with a lifetime incidence of 43% in women and 18% in men, and a median age of onset of 24-5.

The vast majority of headache patients have migraine and need a careful history & physical examination, followed by appropriate treatment, not a brain imaging study.

Studies have shown that a brain imaging study will disclose an “abnormality” in about 1% of unselected headache patients, similar (if not less) than asymptomatic test subjects.

Furthermore, there are potential complications involved with brain imaging:  Some patients are claustrophobic and require sedation, even a general anesthetic.  Many “abnormalities” are innocuous, unrelated to the headache and do not require treatment.  However, these headache patients with such  “incidentalomas”  are left with the conclusion that there is something wrong with them, and may be subjected to further unnecessary follow-up studies.  A few end  up getting unnecessary invasive tests, which actually hurt them.

However, not a day goes past without a migraine patient asking me for a brain imaging study, or for that matter a patient referred to the office worried about an “incidentaloma” identified on a brain imaging study which should never have been done in the first place.

That’s not to say brain imaging is always unnecessary in every headache patient.

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Carefully selected patients with the following “red flag” characteristics might still need a scan:

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This approach is supported by the American Academy of Neurology, whose position is that neuroimaging usually is not warranted for patients with migraine and normal neurologic examination, only for patients with atypical headache features.

Find out more about migraine and headache here.

Epilepsy surgery and functional MRI

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Epilepsy surgery is an option for patients with intractable partial onset seizures that are not controlled by oral medications.  Epilepsy monitoring is used to localize the seizure focus, often a lesion or abnormal area of brain located in the temporal lobe.  That part of the brain is then carefully removed to prevent future seizures:

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A patient with a brain abnormality in the R temporal lobe (top) undergoes brain surgery to remove that area of brain and prevent future seizures.

Epilepsy surgery is very effective and yet still underutilized for treating seizures.

Left temporal lobe resections are more risky that right-sided cases, because the left hemisphere controls language functions in most (even left handed) patients.  Surgeons have to be very careful planning seizure surgery on the left side to be sure that they do not damage brain critical for speech and language and leave the patient with aphasia.

That’s where functional magnetic resonance imaging (fMRI) comes in.  fMRI goes beyond the conventional imaging of brain structure, and can actually localize regional brain functions by detecting changes in regional blood flow in response actual or imagined activity.

fMRI is increasingly being used to evaluate candidates for epilepsy surgery by identifying important functional regions within the brain, including unpredictable patterns of functional reorganization, to prevent unexpected post-operative deficits.  Click here for a link to a paper with illustrative cases.