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Idiopathic Intracranial Hypertension

THE CASE

A 22 year-old female with a medical history of migraines and obesity who presents to the Emergency Department with a headache. Her headache was gradual in onset, but has progressively worsened and has not been relieved with NSAIDs. She describes the headache as dull and pounding with photophobia and phonophobia. She also notes associated nausea but no vomiting, and no associated neurologic complaints. She does note that she thinks during a previous ED visit at an outside hospital she was told she may have “high pressure in her head” but she does not remember the details and is not on any medication for it. A bedside ocular ultrasound was performed and the following images were obtained:

Figure 1. Transverse view of right eye

Figure 1. Transverse view of right eye

Figure 2. Transverse view of left eye

Figure 2. Transverse view of left eye

DIAGNOSIS

An LP was performed and the opening pressure was mildly elevated at 33 cm H2O that decreased to 18 cm H2O with removal of 20 cc of fluid. The remainder of labs and imaging were normal. The patient was diagnosed with Idiopathic Intracranial Hypertension and started on Diamox with outpatient neurology and ophthalmology follow-up. On follow-up she reports resolution of headaches.

DISCUSSION

The ultrasound images were obtained using the 7.5 MHz high frequency linear probe. The ophthalmic setting was used given its lower thermal index, thus decreasing the risk of injury to the eye from heat exposure. For patient comfort, a non-adhesive sterile dressing was placed over eye prior to application of a copious amount of ultrasound gel. The ultrasound probe was placed lightly over the gel in a transverse orientation with probe marker to the patient’s right and with careful attention not to exert pressure on the globe. The probe was angled superiorly and inferiorly slowly until the optic nerve came into view as a black stripe extending posteriorly from the rear of the globe. The nerve sheath diameter was then measured 3 mm posterior to the optic disc. For a more accurate value, an average of 2-3 measurements can be taken.

The relationship between intracranial pressure and optic nerve sheath diameter has been well established. In general, an optic nerve sheath diameter of >5.0 mm is considered abnormal, however there remains some controversy about the exact diameter of the optic nerve sheath that best predicts elevated intracranial pressure. For example, one prospective blinded observational study by Kimberly et al. in 2008 found that an optic nerve sheath diameter >5.0 mm correlated with an elevated intracranial pressure with a sensitivity of 100% and a specificity of 63%. Another 2013 study by Amini et al measured the optic nerve sheath diameter of 50 atraumatic patients undergoing lumbar puncture and found that an optic nerve sheath diameter greater then 5.5 mm correlated with an elevated ICP (>30 mm Hg) with a sensitivity and specificity of 100%. Finally, a third study by Qayyum found a sensitivity of 100% and specificity of 75% for a cutoff of 5.0 mm.

In general, measurement of optic nerve sheath diameter appears to be a useful adjunct for detection of elevated intracranial pressure due to the fact that it is non-invasive, easily performed at bedside, and has good sensitivity for detecting increased intracranial pressure. Though a normal optic nerve sheath diameter does not exclude a life-threatening intracranial process, an elevated optic nerve sheath diameter can further support a diagnosis of elevated intracranial pressure when in the right clinical context.

Faculty Reviewer: Dr. Kristin Dwyer

Additional resources

  1. Blaivas, M. , Theodoro, D. and Sierzenski, P. R. (2003), Elevated Intracranial Pressure Detected by Bedside Emergency Ultrasonography of the Optic Nerve Sheath. Academic Emergency Medicine, 10: 376-381.

  2. Dubourg J, Javouhey E, Geeraerts T, Messerer M, Kassai B. Ultrasonography of optic nerve sheath diameter for detection of raised intracranial pressure: a systematic review and meta-analysis. Intensive Care Med. 2011 Jul;37(7):1059-68.

  3. Irazuzta JE, Brown ME, Akhtar J. Bedside Optic Nerve Sheath Diameter Assessment in the Identification of Increased Intracranial Pressure in Suspected Idiopathic Intracranial Hypertension. Pediatr Neurol. 2015 Aug 28.

  4. Qayyum H, Ramlakhan S. Can ocular ultrasound predict intracranial hypertension? A pilot diagnostic accuracy evaluation in a UK emergency department. Eur J Emerg Med. 2013;20(2):91–97.

  5. Shevlin C. Optic Nerve Sheath Ultrasound for the Bedside Diagnosis of Intracranial Hypertension: Pitfalls and Potential. Critical Care Horizons 2015; 1: 22-30.

  6. Tayal VS, Neulander M, Norton HJ, et al. Emergency department sonographic measurement of optic nerve sheath diameter to detect findings of increased intracranial pressure in adult head injury patients. Ann Emerg Med. 2007 Apr;49(4):508-514.

Brown EM Whit-icisms: Rectal Prolapse

You are called to the bedside by nursing for an elderly patient with the chief complaint of “my insides fell out.” On closer examination, you discover that the patient has suffered from a rectal prolapse. You attempt manual reduction, but have little success. Now what? Check out the latest video by Dr. Whit Fisher to learn what to do.

Intranasal Medications

CASE

A 7 year-old girl presents after falling off a jungle gym.  She has a visible deformity of the left humerus and wrist.  She won’t let the nurse get close enough for a blow-dart, let alone an IV, and your attending slaps the IO kit out of your hands as you desperately try to boost your procedure numbers.  She needs pain relief.  Now what?

BACKGROUND

Intranasal (IN) administration of medications enables rapid systemic delivery, avoids first-pass metabolism, and negates the pain associated with IV access.  Delivery is quick and can be accomplished with minimal training.[1]

The rate limiting factor for IN administration is the area of available nasal mucosa, i.e. your absorptive surface.  Typically, IN administration is limited to volumes less than 1 mL per nostril, perhaps less with the presence of intranasal blood or mucous, necessitating a higher concentration to achieve the desired effect.

The most effective method of IN administration is an atomizer (Figure 1).  Crushing medications or using a syringe as a dropper results in incomplete distribution across the nasal mucosa, imprecise delivery, and unpredictable bloods levels.  Atomizers achieve better delivery, less drug loss to the oropharynx, and greater clinical efficacy.[1]

Figure 1: LMA MAD NASAL atomizer attached to 3 mL syringe

Figure 1: LMA MAD NASAL atomizer attached to 3 mL syringe

IN administration carries a low risk of adverse effects and beyond the time saved via ease of IN administration, the cost is comparable to IV delivery, usually under $10.00 per dose.

INDICATIONS

There has been a push in recent years to develop IN formulations of marketed products, including drugs for migraine management, smoking cessation, and even hormone replacement therapy.[2]  The full breadth of indications for the current IN drug pipeline is beyond the scope of this post, in which we will focus on the indications for which IN medications are used in emergency or pre-hospital settings.

Pain.  Acute pain is a common problem in pediatric medicine, and multiple studies have proven IN administration of opioids to be as effective as the IV route without the need to establish access, and faster onset than IM delivery.  The ease of administration has also made it popular with first responders and practitioners in austere environments.  At Hasbro Children’s Hospital, we commonly use fentanyl.  Dose at 1.5 - 2.0 mcg/kg, allow 10-15 minutes for full effect, and consider co-administration of an oral medication or bridge to IV for longer-term analgesia.[1]

Anxiolysis.  There are numerous reasons children need to stay still during treatments, such as procedures, imaging, or dressing changes.  Midazolam is the most commonly used and well-studied IN anxiolytic, although other options include ketamine and dexmedotomidine.  Although IN midazolam is associated with a transient burning sensation (due to a preservative) in the nares during administration, studies have shown monotherapy provides satisfactory anxiolysis, with minimal risk of adverse events.  Dose at 0.3 - 0.5 mg/kg and allow 5-7 minutes for the medication to take effect.

Seizure.  Because the well-vascularized nasal mucosa is brain-adjacent, IN administration can quickly achieve therapeutic levels in CSF.  In cases without IV access, IN midazolam was found to have a more rapid onset of action than rectal diazepam for better seizure control, and decreased need for intubation and hospital admission.[1]

Overdose.  The opioid epidemic is a national emergency, and with the rise in deaths has come a push for first responders to use naloxone in cases of suspected overdose.  Kits come in 2 and 4 mg doses, and include an ampule of naloxone and an atomizer.

Figure 2: Naloxone IN kit

Figure 2: Naloxone IN kit

ADMINISTRATION TECHNIQUE

Approach from the side.  Even without needles, children will react to seeing a syringe with a lot of anxiety.  Approaching from the side will minimize this, allow you to get in a better position, and achieve better drug delivery.

Use both nostrils.  If you only use one nostril, you’re missing out on an entire half of the nasal mucosa!  Instead of spraying the entire volume into your favorite nares, spread the dose equally between right and left.

Direct the spray.  When you introduce the atomizer, point the tip laterally towards the tip of the ear.  This will afford you better coverage of the turbinates and mucosa.

Use the right concentration.  Using a higher concentration of medication allows you to use less volume, and since absorption is limited by volume when it comes to IN delivery, less drug will be lost.[3] 

SUMMARY 

IN administration of medications is a safe and effective way to manage a number of conditions in situations where other means of drug delivery are inefficient, ineffective, or not available.  As for the patient from our introductory case, she received 25 mcg of IN fentanyl with great improvement in her pain, got x-rays that confirmed a displaced fracture, and tolerated reduction of her wrist with procedural sedation.

Faculty Reviewer: Dr. Chris Merritt

references 

  1. Wolfe TR, Braude DA. Intranasal Medication Delivery for Children: A Brief Review and Update. Pediatrics. 2010; 126: 532-537.

  2. Fortuna A, Alves G, Serralheiro A, Sousa J, Falcao A. Intranasal delivery of systemic-acting drugs: small-molecules and biomacromolecules. Eur J Pharm Biopharm. 2014; 88(1): 8-27.

  3. Using the MAD Nasal Intranasal Mucosal Atomization Device. Teleflex Medical Europe Ltd. Ireland. www.lmaco.com/products. Accessed August 24, 2017.