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Pseudotumor Cerebri vs Hydrocephalus; Is There a Difference?


A case I worked on recently for a client with pseudotumor cerebri (PTC) had concurrent notations for a diagnosis of hydrocephalus, which led me to question the difference between the two. What distinguishes one from the other and how can our client establish PTC as the cause of her problems and the resulting Ventriculoperitoneal (VP) shunt rather than Hydrocephalus? Was one simply part of or a form of the other? Was PTC a variation of hydrocephalus? Was hydrocephalus simply a way of describing a medical symptom or condition that was part of the diagnosis of PTC?

After reviewing the medical record, it seemed apparent that the diagnosis of hydrocephalus was added to the client’s medical record after the shunt was placed. It seemed that one of her physicians was using the term to comment on the physiological state of excessive CSF fluid rather than make a diagnosis of hydrocephalus.

Later in the chart, the diagnosis was added by someone doing a prior authorization for a medication. Thereafter, due to the nature of the electronic medical record, the diagnosis was simply carried forward likely unnoticed.

It proved to be of significance in this case because the litigation was surrounding the PTC diagnosis and not hydrocephalus. The distinction definitely needed to be clarified and if in error identified as such.

After some research, the following is what I found to differentiate the two diagnoses.

What is CSF?

The brain and spinal cord are cushioned by surrounding cerebrospinal fluid (CSF) to protect against injury. Normally, this fluid is then reabsorbed into the bloodstream. If this does not occur, the fluid can build up in the ventricles of the brain causing a number of symptoms and physiologic changes.

HYDROCEPHALUS

Hydrocephalus is a complex disorder that can develop for various reasons. Causes often include obstructive lesions, tumors, or obstructive membranes. Rarely, it is caused by excessive CSF production due to pathologies where CSF production takes place. Frequently it is due to an obstruction in the ventricular system (obstructive or non-communicating type) or interrupted CSF absorption and flow (communicating type).[1]

“Hydrocephalus is excess CSF buildup around the brain, sometimes known as “water on the brain”. It may be congenital and present at birth or can be acquired later at any age.

Typical causes include head injuries, stroke, infections, tumors, and bleeding in the brain. Symptoms include headache, vomiting and nausea, blurry vision, balance problems, bladder control and thinking/memory problems.[2]

Radiological Criteria for Diagnosis

Imaging studies include CT and MRI with the MRI being the preferred imaging study. The most common findings on MRI include ventriculomegaly, enlargement of the third ventricular recesses and lateral ventricular horns; decreased mimillopontine distance and frontal horn angle; thinning and elevation of the corpus callosum; normal or narrowed cortical sulci; periventricular white matter hyperintensities; and aqueductal flow void phenomenon in T2W images (a sign of a communicating hydrocephalus).[3]

Management and Outcomes

Hydrocephalus can permanently damage the brain and if left untreated is usually fatal. With treatment, many people can live normal lives with few limitations. Treatment typically includes surgery to insert a shunt to drain the CSF to another area of the body where it can be reabsorbed.[4]

Management would depend on the cause of hydrocephalus. Endoscopic third ventriculostomy (ETV) is an option for obstructive hydrocephalus caused by aqueductal stenosis and space-occupying lesions. For infections or intraventricular bleeding ETV has considerable effects with confirmed CSF studies.[5]

PSEUDOTUMOR CEREBRI

“PTC is a clinical entity of uncertain etiology characterized by intracranial hypertension.  Symptoms mimic those of a brain tumor but no tumor is found on imaging.

It typically presents with headaches and visual changes in obese women of childbearing age.[6]  Other names for PTC include Idiopathic Intracranial Hypertension (IIH)[7] and Benign Intracranial Hypertension (BIH).[8]

Symptoms may include moderate to severe headaches that originate behind the eyes and are made worse with eye movement; ringing in the ears that pulses with the heartbeat (also known as pulsatile tinnitus); nausea, vomiting or dizziness; blurred or dimmed vision; brief episodes of blindness that lasts a few seconds and may involve one or both of the eyes; difficulty seeing to the side; double vision; light flashes; and neck, shoulder and/or back pain.[9] Patients with PTC also appear to have depression and anxiety to a greater extent than weight matched and healthy controls.[10]

Pathophysiology

In cases of PTC, the fluid is not reabsorbed, thus leading to the increased intracranial pressure (ICP).[11] The exact etiology for this elevated ICP is unknown in nearly 90% of cases and theories include increased blood and tissue volume, increased interstitial fluid volume, increased production rate or outflow resistance, loss of cerebral autoregulation and increased cerebral venous pressure.[12]

Diagnosis

If the above-mentioned signs and symptoms are present, they may only reflect those of generalized intracranial hypertension or papilledema. Documented elevated ICP measured by lumbar puncture while in the lateral decubitus position above 20 cm H2O in normal weight individuals and 25 mm H2O in obese individuals. Other requirements include normal CSF composition; no evidence of hydrocephalus, mass, structural or vascular lesion on MRI or contrast-enhanced CT for typical patients sand MRI and MR venography for all others; and no other cause of intracranial hypertension identified.[13]

Radiological Imaging Study Findings for PTC

Early on, CT studies were utilized to exclude intracranial masses. However, after the development of MR imaging, this would be the recommended imaging for evaluation of any disorder involving vision changes as CT alone has the potential of missing important pathology that may explain increased ICP.[14]

Findings on MRI include empty or partially empty sella/decreased pituitary height; flattened posterior globe/sclera; enlarged ONS (perioptic subarachnoid space); increased tortuosity of optic nerve; enhancement of optic nerve; intraocular protrusion of optic nerve head; and slitlike ventricles.[15]

Management and Outcomes

Originally, PTC was thought to be self-limiting. However, severe deficits of visual acuity might occur in as many as one-quarter of patients if left untreated. Therefore, restoration of visual acuity and resolution of papilledema constitute the primary goals of treatment. For patients without visual symptoms, conservative treatment with medication to reduce the rate of CSF production and weight loss is appropriate but may take time to take effect and frequent follow up including formal visual field testing is required.[16]

Lumbar puncture (LP) is another common treatment to relieve elevated CSF pressure, but this is a painful procedure to have, the effects of which may be short lived and need to be repeated frequently.[17] In some cases (32%), patients experience post lumbar puncture headache and may require an additional procedure of an epidural blood patch. Post LP headaches carry symptoms can last several days and be severe enough to immobilize the patient. If untreated serious complications such as a subdural hematoma and seizures may result and can be fatal.[18] Therefore, this is not a procedure many patients want to continue to have for an extended period of time.

More aggressive measures are reserved for patients who continue to experience vision loss despite conservative treatment as well as for those who initially present with rapid vision loss. Lumboperitoneal shunt surgery is a method to re-route the CSF into the peritoneal cavity. Unfortunately, this method carries with it serious complications ranging from shunt obstruction and shunt-related meningitis or abdominal infection to tonsillar herniation and death. Shunt failure occurs in about half of patients with approximately one tenth having worsening vision following the procedure. As a result, frequent follow up with neurosurgery is required.[19]

Ophthalmologists advocate Optic Nerve Sheath Fenestration (ONSF) as an alternative surgical approach with fewer complications and improved outcomes. Postoperative imaging shows fluid collections adjacent to the site of fenestration and supports CSF extravasation into the orbit thus relieving symptoms. While some studies claim as low as 1% incidence of serious complications, the procedure may result in worsening vision, infection, oculomotor dysfunction and even death and therefore is not without its own risks.[20]

Venous sinus stent placement is yet another treatment option and takes into consideration imaging studies that show stenosis of the cerebral venous sinus and the presumption that venous outflow obstruction constitutes the underlying etiology of most cases. There are conflicting studies on the outcomes for patients undergoing this procedure and the nonrandomized noncontrolled nature of these studies limits assessment of the success of any of these treatment attempts.[21]

CONCLUSION

It seems the distinction is a subtle yet important one.

While the presenting symptoms are quite similar imaging studies differ between the two, and PTC diagnostic criteria actually require the absence of hydrocephalus.

It is a distinction that could be easily overlooked by someone trying to go through a voluminous medical record with no medical training. This is tiring and time-consuming work for the untrained eye. It is a point that will definitely come up in a deposition, and one the lawyer should be aware of and ready for with answers for questions from the opposition.

A positive outcome for your client may hinge on this very fact alone, something so subtle yet so important it could change the outcome of your case.

Don’t risk missing a small issue like this for your client. Enlist the help of a medical professional trained to look for these small subtleties while you work on other important legal aspects of the case. Put an end to digging through endless medical records and start working on the more important aspects of your case such as preparing deposition questions! Know what questions you want to ask and be prepared to answer questions from opposing counsel because you have all the important and relevant facts of your case right in front of you!

Ensure the success of your client’s case today!

Med Legal Pro
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Tracy Liberatore JD, PA

 

[1] Merve Gulbiz Kartal, Oktay Align, Evaluation of Hydrocephalus and Other cerebrospinal Fluid Disorders with MRI: An Update, Insights Imaging 531, 531-41 (2014).

[2] Healthline, http://www.healthline.com/health/hydrocephalus#Overview1 (last visited Sept. 6, 2016); Mayo Clinic, http://www.mayoclinic.org/diseases-conditions/hydrocephalus/basics/symptoms/con-20030706 (last visited Sept. 6, 2016).

[3] Kartal, supra note 1

[4] MedlinePlus, https://medlineplus.gov/hydrocephalus.html (last visited Sept. 6, 2016)

[5] Hailong Feng, M.D., Ph.D, Guangfu Huang, M.D., Xiaoling Liao, M.D., Kai Fu, M.D., Haibin Tan, M.D., Hong Pu, M.D., Yong Cheng, M.D., Weidong Liu, M.D., and Dongdong Zhao, M.D., Endoscopic Third Ventriculostomy in the Management of Obstructive Hydrocephalus: an Outcome Analysis, 100 JNS 626, 626-33 (2004).

[6] A.J. Degnan, L.M.Levy Pseudotumor Cerebri: Brief Review of Clinical Syndrome and Imaging Findings, 32 AJNR 1986, 1986-93 (2011); A.J. Degnan, L.M. Levy, Pseudotumor Cerebri: Brief Review of Clinical Syndrome and Imaging Findings, Am J Neuroradiol. (2011) http://www.ajnr.org/content/32/11/1986.full.pdf+html.

[7]Mayo Clinic, http://www.mayoclinic.org/diseases-conditions/pseudotumor-cerebri/basics/definition/con-20028792 (last visited Sept. 6, 2016).

[8] Leon A. Weisberg M.D., Benign Intracranial Hypertension,54 Med. 197, 197-207 (1975)

[9] Mayo Clinic, supra note 2.

[10] Degnan, supra note 5.

[11] Id.

[12] Degnan, supra note 5.

[13] Id.

[14] Id.

[15] Id.

[16] Id.

[17] Id.

[18] S.V. Ahmen, C. Jayawarna, E. Jude, Post Lumbar Puncture Headache: Diagnosis and Management, 82 Postgrad Med. J. 713, 713-16 (Nov. 2006).

[19]Degnan, supra note 5.

[20] Id.

[21] Id.

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