Anesthetic Management of Patients With Idiopathic Intracranial Hypertension

Author: David Ermak, DO

Anesthesiology News

A 28-year-old woman, with a body mass index of 38 kg/m², presents to the emergency department with a severe headache; she had delivered a healthy newborn 2 days earlier. The headache is exacerbated in the upright position and significantly improved in the recumbent position; the pain radiates to her neck and shoulders. She had a documented accidental dural puncture during epidural catheter placement for labor analgesia. She was diagnosed with idiopathic intracranial hypertension (IIH) 3 years ago when she presented with headaches, blurred vision, and pulsatile tinnitus. The diagnosis was confirmed with lumbar puncture showing an opening cerebrospinal fluid (CSF) pressure of 480 mm H₂O. She was treated with acetazolamide, which was stopped during the pregnancy, and several therapeutic lumbar punctures for CSF drainage.

Introduction

IIH, previously known as pseudotumor cerebri, or benign intracranial hypertension, is a condition of unknown etiology characterized by increased intracranial pressure (ICP) affecting mostly obese women of childbearing age.¹ The incidence is 1:100,000 in the general population; there is an 8:1 female-to-male ratio.² Durcan et al reported a much higher incidence of 19.3:100,000 in women aged 20-44 years weighing 20% or more over their ideal body weight.²

Clinical Signs and Diagnosis

Headache is the most common sign of IIH, occurring in 90% of cases. It is worse in the morning and exacerbated by the Valsalva maneuver. Other symptoms are neck pain, back pain, nausea and vomiting, pulsatile tinnitus, transient episodes of visual loss (visual obscurations), dizziness, photophobia, diplopia (due to cranial nerve VI palsy), etc.^1,3

The diagnosis is made by exclusion, after ruling out other causes for increased ICP. Diagnostic criteria include papilledema, an opening CSF greater than 250 mm H₂O at lumbar puncture performed in the lateral decubitus position, a normal CSF composition, and negative neuroimaging.^4,5 Severe complications such as permanent visual loss rarely occur in untreated patients.⁴ Rosenfeld et al reported four patients presenting with a spontaneous CSF leak manifested by rhinorrhea and otorrhea.⁶

Symptoms may worsen during pregnancy; however, the obstetric approach and outcomes are not influenced by IIH.

Treatment

The main therapeutic goals are symptomatic relief and avoidance of permanent visual loss by reducing the ICP. Acetazolamide, a carbonic anhydrase inhibitor, is the diuretic of choice and effectively decreases CSF production, although it is avoided during pregnancy due to teratogenicity (category C, FDA classification).⁴ Weight loss is recommended but difficult to achieve during pregnancy.

A transient decrease in ICP can be obtained in selected patients, by lumbar puncture and CSF withdrawal (approximately 20 mL). Serial lumbar punctures may offer sustained headache relief, with a long-term success rate of 30% to 40%.⁷

Steroid administration is controversial. Surgical intervention is reserved for patients in whom pharmacologic treatment and serial lumbar punctures have failed. Surgical CSF diversion can be obtained by lumboperitoneal or ventriculoperitoneal shunting. In a retrospective study including 53 IIH patients with CSF surgical diversion, mainly lumboperitoneal shunting (92%), Sinclair et al reported a significant arrest in progressive visual deterioration.⁸ Shunt revision was required in 51% of patients. Optic nerve sheath fenestration to reduce pressure on the optic nerve is reserved for cases of acute or rapidly progressing visual loss.

General Anesthesia

General anesthesia (GA) is best avoided. In addition to usual safety concerns presented by GA in the parturient, acute hemodynamic changes, mainly during laryngoscopy and endotracheal intubation, can further increase the ICP.

Pharmacologic agents reported to attenuate hemodynamic changes in the parturient when administered before induction of GA are remifentanil, magnesium, and labetalol. Among induction agents, propofol is preferred because it decreases the ICP without affecting cerebral perfusion pressure. Succinylcholine is best replaced by rocuronium to avoid an increase in the ICP. According to Anson et al, strategies to avoid hemodynamic changes at extubation in the parturient include appropriate analgesia, preferably avoiding opioids (eg, transversus abdominis plane block); antiemetic prophylaxis; and administration of IV or aerosolized lidocaine to prevent cough.⁵

Neuraxial Anesthesia in IIH

IIH is due to generalized, uniform brain swelling. Unlike in cases of increased ICP due to focal, mass neurologic lesions, neuraxial anesthesia is considered safe in these patients.

Lumbar punctures are therapeutic, and spinal anesthesia requires a small amount of intrathecally administrated fluids with little influence on the ICP. On the other hand, as opposed to spinal anesthesia, large amounts of local anesthetics are required to achieve analgesia and/or anesthesia through an epidural catheter, possibly leading to a further increase in the ICP. However, there are reports of successful uncomplicated labor epidurals in patients with IIH.⁹

Continuous spinal analgesia/anesthesia with intrathecal catheters offers the advantage of excellent analgesia achieved with small amounts of local anesthetics, and the possibility of CSF withdrawal for symptom relief. Combined spinal epidural allows for both CSF drainage and placement of an epidural catheter for fractional administration of local anesthetics and opioids. Month and Vaida reported 2 cases of which symptomatic relief and labor analgesia were successfully obtained with combined spinal analgesia.¹⁰

The patient with IIH having a lumboperitoneal shunt in situ presents special challenges for neuraxial anesthesia, including shunt infection, damage to the lumboperitoneal catheter, or loss of local anesthetic into the peritoneal cavity. A functioning shunt can prevent a sudden ICP increase after epidural injection. Epidural anesthesia for cesarean delivery placed in an intervertebral space away from the shunt was safely reported by Kim and Orbegozo for a patient with a lumboperitoneal shunt.¹¹ Kaul et al recommend radiological confirmation of the shunt location before initiating neuraxial anesthesia.¹²

Postdural Puncture Treatment

Postdural puncture headache causes loss of CSF leading to low ICP, and is therefore a rare paradoxical complication in patients with IIH.⁴ A blood patch to effectively treat postdural puncture headache necessitates injection of approximately 20 mL of autologous blood into the epidural space, which could complicate the underlying condition.

Transnasal sphenopalatine ganglion block to treat postdural puncture headache has gained interest as a minimally invasive alternative to an epidural blood patch. Blocking the sphenopalatine ganglion can reverse the vasodilatation of the meningeal vessels after dural puncture, thereby blocking the parasympathetic flow. The block is achieved by intranasal placement along the floor of the nose with cotton swab sticks saturated with viscous lidocaine and left in situ for 10 minutes.¹³

Conclusion

• In patients with IIH, symptoms may exacerbate during pregnancy.
• Preservation of visual integrity and symptom relief are the main therapeutic goals.
• Spinal anesthesia is safe in patients with IIH; however, large amounts of local anesthetics injected into the epidural space can further increase the ICP.
• A sphenopalatine ganglion block is a viable option to treat postdural puncture headache.

References

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2. Durcan FJ, Corbett JJ, Wall M. The incidence of pseudotumor cerebri. Population studies in Iowa and Louisiana. Arch Neurol. 1988;45(8):875-877.
3. Wall M, Kupersmith MJ, Kieburtz KD, et al. The idiopathic intracranial hypertension treatment trial: clinical profile at baseline. JAMA Neurol. 2014;71(6):693-701.
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5. Anson J, Vaida S, Giampetro DM, et al. Anesthetic management of labor and delivery in patients with elevated intracranial pressure. Int J Obstet Anesth. 2015;24(2):147-160.
6. Rosenfeld E, Dotan G, Kimchi T, et al. Spontaneous cerebrospinal fluid otorrhea and rhinorrhea in idiopathic intracranial hypertension patients. J Neuroophthalmol. 2013;33(2):113-116.
7. Aly EE, Lawther BK. Anaesthetic management of uncontrolled idiopathic intracranial hypertension during labour and delivery using an intrathecal catheter. Anaesthesia. 2007;62(2):178-181.
8. Sinclair AJ, Woolley R, Mollan SP. Idiopathic intracranial hypertension. JAMA. 2014;312(10):1059-1060.
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10. Month RC, Vaida SJ. A combined spinal-epidural technique for labor analgesia and symptomatic relief in two parturients with idiopathic intracranial hypertension. Int J Obstet Anesth. 2012;21(2):192-194.
11. Kim K, Orbegozo M. Epidural anesthesia for cesarean section in a parturient with pseudotumor cerebri and lumboperitonealshunt. J Clin Anesth. 2000;12(3):213-215.
12. Kaul B, Vallejo MC, Ramanathan S, et al. Accidental spinal analgesia in the presence of a lumboperitoneal shunt in an obese parturient receiving enoxaparin therapy. Anesth Analg. 2002;95(2):441-443.
13. Kent S, Mehaffey G. Transnasal sphenopalatine ganglion block for the treatment of postdural puncture headache in obstetric patients. J Clin Anesth. 2016;34:194-196.