Our patient is a 29-year-old male who presented to a local urgent care for a 10 day progressively worsening headache, described as waxing and waning, with associated leg weakness. Three days prior, he was seen by his primary care physician (PCP) and diagnosed with migraines.
However, his headache continued to worsen over the next three days and had an episode of not acting like himself. The urgent care provider reported that prior to EMS arrival, the patient had one episode of violent emesis after being asked to sit up. He then subsequently collapsed, with eyes open, and had full body rigidity, without clonic movement, that lasted for about two minutes.
EMS found the patient to be conscious but appeared uncomfortable in the supine position. His vitals were unremarkable. Pupils were equal and reactive to light and the remainder of his neurologic exam was unremarkable with no deficits. Cincinnati Stroke Scale was negative.
The patient endorsed nausea and photophobia but denied head trauma, neck and back pain, fevers or recent travel. Past medical history is unremarkable except for remote Lyme Disease.
EMS initiated transport with two paramedics. Enroute, the patient suddenly had an episode of aphasia and dysarthria lasting for about two minutes with spontaneous resolution. A second Cincinnati Stroke Scale assessment was negative. Because of the sudden neurologic changes, a possible stroke alert was initiated. The remainder of the patient’s transport was unremarkable.
Upon hospital arrival, he continued to be alert and oriented and was sent directly to imaging. A Computed Tomography (CT) scan showed moderate to severe ventriculomegaly with concern for a mass at the level of the Foramen of Monro causing obstructive hydrocephalus. An urgent neurosurgery consult was placed.
The patient then developed signs of altered mental status with agitation. He progressed to signs of the Cushing triad with bradycardia, hypertension and altered respirations. Because of the concern for significant deterioration, he was transferred to the neurosurgical intensive care unit (ICU) where bilateral external ventricular drains (EVD’s) were placed.
EVD’s are catheters placed by neurosurgeons directly into the lateral ventricles via burr holes in the skull to monitor pressure readings and divert cerebrospinal fluid (CSF). This intervention was indicated due to signs of elevated intracranial pressure (ICP) and concern for impending brain herniation. Magnetic Resonance Imaging (MRI) was subsequently performed and demonstrated a 1.7 cm x 1.7 cm x 1.7 cm colloid cyst.
The decision was made to proceed with endoscopic surgical intervention by neurosurgery and pathology confirmed the colloid cyst. He was discharged on postoperative day four. At the time of discharge, he was neurologically intact with normal gait, mental status and memory function.
A colloid cyst is a benign, rare primary brain tumor representing about 2% of primary brain tumors and 15-20% of intraventricular masses.1 Initially, colloid cysts can be difficult to differentiate from other intraventricular lesions, including other types of cysts, tumors, infections, hemorrhage, or parenchymal lesions that can be periventricular.
Little is known regarding the etiology, but it is thought to be derived from either primitive neuroepithelium or endoderm.4 The colloid cyst is lined by epithelium and filled with a gelatinous material. Almost all colloid cysts develop at the anterior aspect of the third ventricle.1 It is thought to affect men and women equally and is predominantly diagnosed in the third through seventh decade of life.1,4
Management is guided by the patient’s presentation, given symptoms caused by colloid cysts are non-specific. Other causes of acute neurologic deterioration must be ruled out, such as stroke, hemorrhage or intoxication. Once acute hydrocephalus is suspected and confirmed on CT imaging, the elevated ICP must be relieved after airway, breathing and circulation (ABC’s) are secured. This may include placement of an EVD at the discretion of a neurosurgeon, in addition to medical management with acetazolamide, head of bed elevation to 30 degrees, and frequent neuro checks.7
Once a colloid cyst is known/suspected, treatment options include surgical excision via craniotomy with transcallosal or transcortical routes, endoscopic removal or stereotactic aspiration.5 Treatment is not always warranted; many factors are considered prior to surgery, including location, size and symptoms. Risks and benefits of the various approaches will not be further discussed here but the decision on the optimal approach is important as the lining of the cyst needs to be removed in its entirety to reduce the chance of recurrence.
From an EMS perspective, identifying a patient with increased ICP should be the focus, no matter what the exact etiology is.
Headaches are one of the most common ED complaints. They can be classified as primary or secondary, with secondary being life-threatening if not diagnosed and treated in a timely manner. Some secondary examples include intracranial hemorrhage (ICH), meningitis, cerebral venous thrombosis, posterior reversible encephalopathy syndrome (PRES), carbon monoxide poisoning and acute hydrocephalus.2 Most headaches in the ED are benign, but special attention needs to be directed toward red flags in a focused history and physical in order to exclude secondary causes of headaches.
Our patient’s initial presentation to his PCP pointed towards migraine headache, as common symptoms include nausea/vomiting, photophobia and limitations in daily function. However, headache, emesis and altered mental status are also common warning signs of increased intracranial pressure. Retrospectively speaking, it’s notable that our patient’s emesis and possible “drop attack” were postural, therefore special attention must be given towards the duration, progression, and character of symptoms.
Drop attacks (sudden collapse without loss of consciousness) and syncope can be indicative of an acute obstructive process, such as an intracranial bleed or hydrocephalus. Traumatic brain injuries can also manifest with loss of consciousness; however, a traumatic mechanism of injury is usually uncovered in the patient’s history.
Hydrocephalus is defined as an increase in CSF volume intracranially. It can be divided into two forms, obstructive and nonobstructive. Obstructive refers to a mechanical blockage in the ventricular system or the subarachnoid space.1 Nonobstructive hydrocephalus takes a more indolent course and is less common in the acute setting. Obstruction can take place in any part of the ventricular system and etiologies can be congenital or acquired.
Often times, acute presentation is secondary to CSF shunt complications, subarachnoid hemorrhage (SAH), or severe head trauma.1 Our patient, however, was found to have a colloid cyst obstructing the third ventricle, presenting as acute obstructive hydrocephalus, highlighting the importance of considering less common causes of acute hydrocephalus that present as severe headaches.
Colloid cysts are typically incidental findings on brain imaging.1 Epithelium-lined cysts in general tend to grow slowly over time, however some can grow faster than others. Because the most common location for these to arise is at or near the foramen of Monro, pure mechanical blockage leads to symptoms because they can physically obstruct outflow of CSF from the lateral ventricles, leading to hydrocephalus.1 The normal path of CSF flow goes from the lateral ventricles to the third ventricle via the foramen of Monro, then into the fourth ventricle via the aqueduct of Sylvius, then to the subarachnoid space.10
According to Singh et al, larger cyst size was associated with higher mortality, regardless of intervention.3 In their study of 140 patients, the mean cyst size was 2.12 cm in males and 1.59 cm in females. However, in patients who died from acute neurologic decline or sudden death, the mean size was 2.05 cm. The mean size was 1.64 cm in those who survived, raising the idea that the size of the cyst correlates to the degree of symptoms. Singh et al examined five factors to see if they are associated with symptomatic patients: 1) younger age, 2) larger cyst size, 3) ventricular dilation, 4) headaches and 5) increased signal on T2-weighted MRI.3
Age was not a predictive factor for survival outcome. Larger cyst size correlated with higher mortality, as patients who died had a median cyst size of 1.9 cm and 1.2 cm in those who did not. When hydrocephalus was found to be present in those with acute neurologic decline, prognosis was poor with 69% mortality. In patients who presented in extremis or in a neurologically deteriorated state, all patients without surgical intervention died compared to 48% of patients who had surgical intervention.
Non-communicating (obstructive) hydrocephalus may present acutely and manifest as non-specific symptoms including but not limited to headache, nausea, vomiting, lethargy, coma and death.5
Depending on the progression, urinary incontinence, ataxia, altered mental status and memory issues may develop slowly. Physical exam findings may also be subtle, if any at all. This includes lethargy, failure to follow upward gaze, ataxia, hyperreflexia, seizures, drop attacks, gait disturbance or papilledema.5
Because of the obstructive nature, patients may present with a thunderclap headache (maximal intensity and sudden onset) or even sudden collapse, emphasizing the similarity to the classic presentation of a brain bleed. Further, in traumatic cases, such as patients presenting after a fall, diagnosis may be easily confused with hemorrhage as well.
Little is known about mechanisms of sudden death in patients with symptomatic colloid cysts, but three theories have been postulated.3 First is full obstruction as the cyst moves on its pedicle as a cause of intracranial hypertension or herniation. Second is acute hemorrhage into the cyst with subsequent obstruction, and third being cardiac arrest from localized pressure causing hypothalamic-mediated autonomic cardiac reflex disruption.3
As part of the evaluation, patients can be at risk of presenting with acute hydrocephalus and rapid neurologic deterioration with herniation, therefore ABC’s must be secured. If patients present alert with a known complaint of headache, special attention must be paid to a thorough neurologic exam. Neurologic deficits may be lacking, therefore the gold standard in diagnosis is still neuroimaging. CT and MRI are the best modalities.
CT head is more efficient in identifying acute hydrocephalus. Colloid cysts classically appear as sharply demarcated hyperattenuated masses at or near the third ventricle on CT.8,9 An MRI can classify the cysts better and is therefore the preferred modality. Classically, they are hyperintense on T1 sequencing, but can vary from isointense to hypointense too, and the structure should not enhance with gadolinium.8 On T2 weighted imaging, appearance can vary. On FLAIR sequencing, they can have similar intensity to CSF.8 In our patient, the colloid cyst of the third ventricle caused blockage of the foramen of Monro leading to ventriculomegaly (Fig. 1-2).
Acute obstruction leads to increased CSF volume, therefore increasing the pressure inside the cranium, a tightly fixed space. As the ICP rises, blood flow to the brain becomes restricted. Important from the perspective of EMS providers, early signs of increased ICP are generally non-specific, including headache, restlessness and confusion.7 It can progress to slowing of speech, voluntary movements, sensations and extraocular movements.
Pressure near the medulla can cause projectile vomiting and arrhythmias. Late signs include decreased level of consciousness, Cushing triad (bradycardia, hypertension, and altered respirations), mydriasis and loss of extraocular movements, which are both signs of impending herniation.7 Our patient quickly progressed from having signs of confusion early in the day, to agitation and ultimately to the Cushing triad.
Early identification of increased ICP is crucial due to the possibility of rapid neurological decline. In the prehospital environment, action can be taken to help mitigate increased ICP. First and foremost is getting to the nearest ED with a CT scanner. This includes elevating the head to 30 degrees, avoiding overhydration, maintaining normal oxygen, using standard of care benzodiazepines in case of seizures, stroke assessments if necessary, and administering an osmotic agent when edema is suspected secondary to trauma and head injuries.
Sodium bicarbonate 8.4% prefilled syringes can easily be administered as a loading dose of two ampules, equivalent to 100 mL. This follows the traditional in-hospital treatment using hypertonic saline or mannitol to treat rises in ICP.6 Overall, suspecting and managing increased ICP in the prehospital environment is challenging. This case exemplifies the need to have a broad differential of intracranial processes when patients complain of headache.
1. Hydrocephalus. (n.d.) In Emergency Central. Retrieved November 5, 2019 from https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307018/all/Hydrocephalus.
2. Long, B. (November 20, 2017). emDocs Cases: Headache Management in the ED. In emDocs. Retrieved November 5, 2019 from http://www.emdocs.net/emdocs-cases-headache-management-ed/.
3. Singh H, et al. Factors influencing outcome in patients with colloid cysts who present with acute neurological deterioration. Journal of Clinical Neuroscience. 2018;54:88-95.
4. Ahmed S, Javed G, Laghari A, et al. (October 05, 2018) Third Ventricular Tumors: A Comprehensive Literature Review. Cureus 10(10): e3417. DOI 10.7759/cureus.3417.
5. Tenny S, Thorell W. (October 23, 2019). Colloid Brain Cyst. In: StatPearls. Retrieved November 2, 2019 from https://www.ncbi.nlm.nih.gov/books/NBK470314/#_NBK470314_pubdet_.
6. Bourdeaux C, Brown J. Sodium bicarbonate lowers intracranial pressure after traumatic brain injury. Neurocritical Care. 2010;13.1:24-28.
7. Pinto VL, Tadi P, Adeyinka A. (March 26, 2019) Increased intracranial pressure. In: StatPearls. Retrieved November 15, 2019 from https://www.ncbi.nlm.nih.gov/books/NBK482119/.
8. Bell DJ, Gaillard F, et al. (n.d.) Colloid cyst of the third ventricle. In: Radiopaedia. Retrieved November 5, 2019 from https://radiopaedia.org/articles/colloid-cyst-of-the-third-ventricle?lang=us#nav_radiographic-features/.
9. Armao D, Castillo M, Chen H, et al. Colloid cyst of the third ventricle: imaging-pathologic correlation. American Journal of Neuroradiology. 2000;21:1470-1477.
10. Khasawneh A, Garling R, Harris C. Cerebrospinal fluid circulation: What do we knowand how do we know it? Brain Circulation. 2018;4(1):14-18.