Archive | May, 2016

insulin memory aid: Can I tell from the name if its short or longer acting?

30 May

nice memory tool pulled from an April emdocs post:

 

INSULINs:

rapid acting: LOGs (e.g. NovoLog, HumaLog)

short to intermediate acting: LINs

  • Lin R – Short acting (NovoLin R, HumuLin R)
  • Lin N – Intermediate acting (NovoLin N, HumuLin N)

long acting: other stuff (e.g. Lantus, Levemir)

 

There you go. Check out the original post, which has a nice chart on the pharmacokinetics, as well as this handy visual aid, too.

screen-shot-2015-08-16-at-10-53-37-am

 

References: http://www.emdocs.net/core-em-pharmacology-of-insulins/

Cranial Nerve VI Palsy

23 May

Submitted by Christina Brown, M.D.

Definition 

  • Abducens nerve, CN VI
  • a somatic, efferent (motor) nerve that controls a single muscle; lateral rectus. 
  • sixth cranial nerve has the longest subarachnoid course of all the cranial nerves. 
  • sixth nerve nucleus is located in the pons, just ventral to the floor of the fourth ventricle and just lateral to the medial longitudinal fasciculus (MLF) [5].

RBO revisada JAN-FEV-13-en.pmd

Epidemiology 

study of 213 patients with unilateral isolated sixth nerve palsies, non-traumatic

  • 78% experienced spontaneous recovery of their palsy,
  • 37% recovering by 8 weeks
  • 74% by 24 weeks [3].
  • Only 16% failed to recover; of this group, however, almost 40 percent had serious underlying pathology accounting for their palsy.

 

Presentation 

  • primarily c/o horizontal diplopia (double vision producing a side-by-side image with both eyes open). 
  • Patients with idiopathic sixth nerve palsy often present with the sudden onset of horizontal diplopia that is better at near and worse at a distance.
  • Patients also may present with a head-turn to maintain binocularity and to minimize diplopia. [5].  
  • A sudden onset distinguishes idiopathic sixth cranial nerve palsies from tumor or myasthenia gravis [6]. 
  • Other things to pay particular attention to when dealing with sixth nerve palsies
    • fifth nerve (reduced facial sensation, often around the upper face and cornea) pointing to a lesion in the cavernous sinus
    • papilledema, suggesting a mass lesion causing raised intracranial pressure and displacement of the brainstem and thus stretching of one or both sixth nerves.

 

DDx – Giant cell arteritis, Mass Lesion, Myasthenia Gravis, Lyme disease, syphilis, cavernous sinus lesion, Medial Orbital Wall Fracture, Horner’s Syndrome, diabetes, meningitis [1,6]

Evaluation – For idiopathic CNVI palsy, spontaneous improvement over several weeks to months is expected, and failure to improve suggests more serious intracranial pathology.

  • 1st – Onset of presentation? A sudden onset distinguishes idiopathic sixth cranial nerve palsies from tumor or myasthenia gravis.
  • 2nd – Is a single nerve involved? Involvement of other nerves, even the opposite cranial nerve (eg, bilateral sixth nerve palsy), suggests a more serious underlying pathology.
  • 3rd – Is there a medical excuse for the problem? Diabetes, myasthenia gravis, etc.  As an example, one is more likely to work up a young person with a sixth nerve palsy than an older person in his seventies.
  • 4th – Headache? The presence of severe headache of sudden onset demands an urgent evaluation for cerebral aneurysm
  • 5th – Signs of improvement over time? Almost always point to a benign process. Isolated fourth or sixth never palsies can be observed for a few weeks. More extensive work-up should be done if the palsy does not resolve or if other symptoms appear. Persistent esotropia may require a surgical procedure.

 

Management 

  • Ophthalmology C/S if bilateral nerve involvement, CNV involvement, persistent esotropia.
  • Neuroimaging if high clinical suspicion for mass lesion, cerebral aneurysm.
  • If elevated ESR, CRP pointing toward temporal arteritis, start high dose steroids.

 

References: 

  1. http://www.uptodate.com/contents/overview-of-diplopia?source=search_result&search=sixth+nerve+palsy&selectedTitle=1~50#H23
  2. Patel SV, Holmes JM, Hodge DO, Burke JP. Diabetes and hypertension in isolated sixth nerve palsy: a population-based study. Ophthalmology 2005; 112:760.
  3. King AJ, Stacey E, Stephenson G, Trimble RB. Spontaneous recovery rates for unilateral sixth nerve palsies. Eye (Lond) 1995; 9 ( Pt 4):476.
  4. Gutman I, Levartovski S, Goldhammer Y, et al. Sixth nerve palsy and unilateral Horner’s syndrome. Ophthalmology 1986; 93:913.
  5. http://emedicine.medscape.com/article/1198383-overview
  6. Kline LB, Glaser JS. Bilateral abducens nerve palsies from clivus chordoma. Ann Ophthalmol 1981; 13:705.
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visual aid: facial nerve blocks

16 May

some very nice nerve landmark photos via a recent EM Docs post:

nerve lineup

the key takeaway here is that you can draw a line vertically through the middle of the eye, and that’s your rough horizontal landmark to aim your needle for a nerve block.

Check out the site, which has a few other useful photos and tips, including this one for the auricular block:

screen-shot-2016-04-24-at-7-06-39-pm-546x1024

 

There you go.

 

References: emdocs post

Pneumocephalus

9 May

submitted by Christina Brown, M.D.

Definition – Air in the cranial vault.  

Mechanically speaking, intracranial air becomes trapped and expands due to a ball valve effect resulting in mass effect, can result in headache and signs and symptoms of increased ICP [5].  

Usually associated with neurosurgery, barotrauma, basilar skull fractures, sinus fractures, nasopharyngeal tumor invasion and meningitis [1, 2].

Presentation

  • Headache and altered consciousness are the most common symptoms [3].
  • Tension pneumocephalus = neurosurgical emergency

Imaging

  • X-rays can diagnose pneumocephalus, but CT scan is the modality of choice.
  • Classical CT sign of tension pneumocephalus = “Mount Fuji sign”: the massive accumulation of air that separates and compresses both frontal lobes and mimics the large volcano in Japan.  

 

Management

Conservative 

  • Neurosurgery C/S. In the vast majority, post-operative pneumocephalus is an expected finding in essentially all post-craniotomy patients.  Most cases of pneumocephalus resolve spontaneously, and conservative management should be provided.  
  • Non-operative management involves oxygen therapy, keeping the head of the bed elevated, prophylactic antimicrobial therapy (especially in post-traumatic cases), analgesia, frequent neurologic checks and repeated CT scans. 

 

Operative – In cases of tension pneumocephalus, a burr hole may need to be performed to relieve pressure. 

 

References

  1. Yildiz A, Duce MN, Ozer C, et al. Disseminated pneumocephalus secondary to an unusual facial trauma. Eur J Radiol. 2002;42:65–68. doi: 10.1016/S0720-048X(01)00383-7. 
  2. Jenson MB, Adams HP. Pneumocephalus after air travel. Neurology. 2004;63:400–401.
  3. Kapoor T, Shetty P. J Emerg Med. 2008;35:453–454. doi: 10.1016/j.jemermed.2007.03.046. 
  4. Satapathy GC, Dash HH. Tension pneumocephalus after neurosurgery in the supine position. Br J Anaesth. 2000;84:115–117. 
  5. Satapathy GC, Dash HH. Tension pneumocephalus after neurosurgery in the supine position. Br J Anaesth. 2000;84 (1): 115-7. Br J Anaesth (abstract)
  6. pictures