Tag Archives: neurology

SEIZURE PEARLS

17 Jul

submitted by Amit Kumar, M.D.

Generalized seizure

-Large parts of bilateral cerebral hemispheres involved
-LOC for the most-part. Post-ictal state (headache, drowsiness) common.
-Examples: Tonic-clonic (grand mal), absence (petit mal), myoclonic, tonic, atonic

Partial seizure

-Simple partial: limited to focal area in single cerebral hemisphere. Usually no post-ictal period.
-Complex partial: simple partial + LOC. Generally associated with an aura (smell, taste, visual hallucination, emotion). Post-ictal period common.

Status epilepticus

-Continuous seizure lasting over 5 mins/more than two discrete seizures without interval recovery

EtOh-withdrawal seizure

-Typically generalized, may begin within 6h of cessation/decreased consumption
-“Kindling phenomenon”: risk and severity of seizure increases (and threshold decreases) with each withdrawal episode

Febrile seizure

-Seizure in child (~3 mo-6y) with associated fever (>38C), without evidence of intracranial infection or other defined cause
-Types: Simple: Generalized, last <15 mins, don’t recur in 24h period; Complex: Focal, last >15 mins, recur in 24h period
-Subsequent epilepsy risk: simple (1-2%, only slightly above general population), complex (~5-10%)

Management

-ABCs, airway, O2, monitor
-If intubating: benzo for induction and short-acting paralytic (succ) to not mask ongoing seizures. Post-intubation sedation: benzo/propofol gtt
-Labs (check for electrolyte disarray, anemia), infectious workup, home anticonvulsant levels, neuroimaging prn
-Check POCG (dextrose for hypoglycemia), probe on abdomen (Mg for eclampsia), check drug-list (Vit B6 for INH toxicity)

Treatment

-Benzodiazepines (enhance GABA-mediated neuronal inhibition): lorazepam (Ativan), diazepam (Valium), midazolam (Versed)
-Phenytoin (reduces repetitive firing of action potentials via Na-channels). Administer IV/PO (rare)
-Fosphenytoin. Administer IV/IM
-Phenobarbital (enhances GABA)
-Valproic acid (increases GABA)

Seizure abortive meds

References

-Nelson KB, Ellenberg JH. Predictors of epilepsy in children who have experienced febrile seizures. N Engl J Med 1976; 295:1029.
-Rosen, Peter, John A. Marx, Ron M. Walls, and Robert S. Hockberger. Rosens emergency medicine: concepts and clinical practice. 8th ed. Vol. 2. Philadelphia: Elsevier Saunders, 2014. (& photo)
-Schaider, J. & Barkin, R. & Hayden, S. & Wolfe, R. & Barkin, A. & Shayne, P. & Rosen, P. (2011). SEIZURE, ADULT. ROSEN & BARKIN’S 5-MINUTE EMERGENCY MEDICINE CONSULT. Retrieved February 13, 2017 from http://www.r2library.com/Resource/Title/1608316300/ch0019s14706

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visual aid: dense MCA sign

6 Mar

was reminded of the useful dense MCA sign by this article in December’s JEM (good pictures, though the article was written by radiologists with variably subtle CT findings):

denseMCA

QUICK HITS:

increased attenuation of [a segment of] the middle cerebral artery 

can give an MCA dot sign when the vessel is seen end-on.

usually seen in 90 min of the event

for more visual aids, check out radiopaedia.org, which has a video link + several cases you can scroll through like a real CT scan.

quick imaging overview with pictures over here as well.

 

References: JEM article; radiopaedia.org + picture; radiology assistant + picture

 

Pilocytic Astrocytoma

6 Sep

RAGING HYPOTHETICAL:

Your next patient is a 7 year old boy presenting with headache. Mom tells you he has been “dealing with headaches all summer”, but things got worse a few days ago when he started having nausea, vomiting, and fatigue.

On your exam, the patient’s vital signs are stable. He is sitting in mom’s lap, irritable, and uncooperative with the exam.

During the neuro exam, you notice his unsteady gait and dysmetria isolated to the left.

A head CT shows the following:

 A large cystic left cerebellar mass with a solid nodule, a typical imaging appearance of a pilocytic astrocytoma. 

 

Now, when you share this with mom and dad, first they are shocked and upset, followed by a barrage of questions. What can you tell them to expect?

 

Pilocytic astrocytomas are well-circumscribed, slow-growing tumors representing 20% of all childhood brain tumors.

 

The clinical manifestations depend on the location of the tumor, but may include visual deficits if the optic pathways are involved, obstructive hydrocephalus, ataxia, and a focal neurological exam.

 

The history of illness is typically long since these tumors are slow-growing.

 

The main therapy is surgical resection, which is curative if the entire tumor is removed. Radiation and chemotherapy are typically not required unless the tumor is progressive or unresectable (think brainstem, spinal cord, hypothalamus).

 

The prognosis is excellent, with the 5-year recurrence-free survival of greater than 90% after total resection. Malignant transformation in children is rare.

 

The bottom line:

pilocytic astrocytomas typically favor a good prognosis depending on tumor location, extent of tumor resection, side effects of surgery, chemotherapy and radiation.

 

Submitted by K Estes:

 

Source: Daroff: Bradley’s Neurology in Clinical Practice, 6th ed.; picture

 

 

Myasthenia gravis (quick review)

14 Mar

rare autoimmune disorder

antibodies form against acetylcholine (ACh) receptors 

 

common presentations (though it can produce weakness in any muscle group):

  • ocular symptoms (eg, ptosis, diplopia) occur in 50 percent
  • bulbar symptoms (eg, dysarthria, dysphagia, fatigable chewing) – 15 percent
  • isolated limb weakness occurs – 5 percent
  • Myasthenic crisis – occurs when respiratory and/or bulbar muscle weakness produces acute respiratory distress.

 

Edrophonium chloride (Tensilon test)

  • acetylcholinesterase inhibitor
    • prolongs the presence of acetylcholine in the neuromuscular junction
    • immediate increase in muscle strength
  • rapid onset (30 to 45 seconds)
  • short duration (5 to 10 minutes)
  • not without risk:
    • patients frequently develop increased salivation, mild GI cramping
    • symptomatic bradycardia or bronchospasm can occur.
    • Atropine (0.4 to 0.6 mg) should be ready before edrophonium is given (just in case)
    • relative contraindications: advanced age, cardiac disease, bronchial asthma
  • A positive test is not specific for myasthenia. can also occur in other neurological conditions.

 

Elective intubation should be considered if:

  • Vital Capacity less than 20 mL/kg
  • MIF (maximum inspiratory flow) is worse than -30 cmH20.

 

RSI Tip:

  • depolarizing paralytic agents (eg, succinylcholine) are less predictable in myasthenia gravis.
  • relative lack of ACh receptors makes these patients relatively resistant to succinylcholine
  • higher doses must be used to induce paralysis.
  • Once paralysis is achieved, it may be prolonged.
  • nondepolarizing agent (ie, rocuronium, vecuronium) is preferred

 

Submitted by H. Reed-Day.

 

References: uptodate.com; emedicine article; picture

 

References:

want less post-LP headaches? re-insert the stylet

20 Dec

Best evidence topic report by Deibel et al. basically found one article worth its snuff:

Strupp et al:

  • 600 neurology patients getting LPs (21 gauge needle)
    • 300 to stylet replacement before needle removal
    • 300 not reinserted
  • followed-up for post-LP headache within 7 days
  • 49/300 (16%) post-LP headache when stylet NOT re-inserted
  • 15/300 (5%) when stylet reinserted.
  • Post-lumbar puncture syndrome was also less severe (2.8 v 4.5 scale of 10) if stylet reinserted

 

BOTTOM LINE:

Replacing the stylet before removal of the spinal needle may help decrease the incidence of post-lumbar puncture headaches

 

References: best evidence report; original article; picture