Andrea and her Rare Tumor of the Fourth Ventricle

Andrea (name changed) is in her 40’s and runs a busy household. For a few months, she had been waking up with a headache. Not daily at first, though recently they had become more frequent. The headache would resolve after being up a while, but recently it has lingered through the day.

She scheduled a visit with her family doctor.  There, she described a frontal, throbbing, and, at times, sharp headache. The past couple of weeks, she reported, episodes of numbness and weakness in the right hand and dizziness when changing positions.

A neurological examination revealed moderate difficulty walking with one foot in front of the other. Otherwise, the exam was normal. Her provider ordered an MRI of the brain which revealed the ventricles (spinal fluid spaces inside the brain) to be somewhat larger than normal – a condition called hydrocephalus (Figure 1). Something was blocking the flow of spinal fluid through the ventricles, but what could it be?

Figure 1 – Cross-section MRI showing enlargement of the ventricles (dark fluid filled spaces) in the center of the brain.

In the side view (sagittal) MRI, a tumor could be seen inside of the fourth ventricle, the fluid space between the brainstem and the cerebellum (Figure 2).  A cross section MRI scan (Figure 3), performed after she had received received intravenous contrast (“dye” material given through a vein), clearly outlined the tumor (Figure 3). It was blocking blocking cerebrospinal fluid (CSF) flow and enlarging the ventricle. This explained why the ventricles in the upper brain looked too big.

Figure 2 – Side view MRI of the brain showing the tumor between the brainstem and the cerebellum.

Figure 3 – Cross section view of the lower brain area. The tumor is easily after intravenous contrast was given.

Comment
There are various treatments for brain tumors. Some tumors are first diagnosed with a needle biopsy, while others may be treated with specialized radiation called radiosurgery. However, in many cases, surgery is required to remove the tumor. In Andrea’s case, the tumor was blocking CSF flow. If the blockage became worse, which was very likely since the tumor would keep growing, it could render her unconscious and jeopardize her life. A needle biopsy would not resolve the CSF blockage.  

Surgery
After careful discussions with her and her husband, she was readied for surgery. The plan was to reach the tumor through a cranial opening (craniotomy) at the back of the head.  Once the membrane surrounding the brain was exposed and opened, a path would be developed between the two halves of the lower cerebellum (called the cerebellar tonsils).  With gentle separation of the cerebellar tonsils, the lower part of the tumor came into view (Figure 4).

Figure 4 – Microphotograph during surgery showing the lower portion of the tumor between the cerebellar tonsils.

After a biopsy was obtained, the tumor was removed through microsurgery using the neurosurgical microscope, microsurgical instruments, and an ultrasonic aspirator – an instrument whose tip vibrates at ultrasonic frequencies and morselize (break-down) the cells. (This tool has replaced the laser that came into use in the 1980’s, although there are still a few applications for it today). Using the gentle action of the ultrasonic aspirator and microsurgical dissection, the tumor was steadily removed. Inspection of the floor of the fourth ventricle showed no residual tumor (Figure 5).

Figure 5 – View of the bottom of the fourth ventricle after the tumor was removed.

Andrea stayed in the hospital for … days and was then discharged home with her family. She steadily resumed her normal activities. Follow-up brain MRI scans have shown no residual tumor (Figure 6). Happily, she has recovered completely and is back to her busy life.

Figure 6 – MRI scan performed 7 months after surgery shows no evidence of tumor.

Comment
Tumors growing within the cerebral ventricles are rare in the adult population. In one study of 73 persons with intraventricular tumors, the types of tumor found included:

• medulloblastoma
• ependymoma
• epidermoid
• cystercircosis
• astrocytoma
• subependymoma

Other tumors found within the ventricles are a choroid plexus papillomas and meningiomas. A metastasis from a tumor elsewhere in the body can also develop within the ventricles.

The pathological examination of Andrea’s tumor revealed it to be a choroid plexus papilloma. Follow-up MRI scans within the first year following surgery have shown no tumor.  The chances of the tumor coming back from unseen cells buried within the tissues are about 10%. MRI scans will be performed on a regular basis for a few years.

REFERENCE

Intraventricular mass lesions.

Morrison G, Sobel DF, Kelley WM, Norman D.

Radiology. 1984 Nov;153(2):435-42.

http://preview.ncbi.nlm.nih.gov/pubmed/6333046

Syringomyelia

Normally, cerebrospinal fluid (CSF) flows from the ventricles (fluid pockets) of the brain down the spinal canal and back to the brain. Spinal fluid pulsates in this manner with every beat of the heart- over 100,000 times per day. When there is a blockage in the flow of spinal fluid, an abnormal CSF pathway forms, resulting in a syrinx or syringomyelia. Syringomyelia (or syrinx) is an abnormal fluid cavity that forms inside the spinal cord.

The most common cause of Syringomyelia is the Chiari I malformation which causes obstruction of spinal fluid at the base of the skull.  Other causes can be trauma, tumor, or arachnoiditis. Syringomyelia  can cause pressure on the nerves that control pain, sensation and strength.

Symptoms of syringomyelia include (but are not limited to) pain in the neck or back, pain in the arms/hands, numbness, tingling, and sometimes weakness of the arms/hands/lower extremities.

The test of choice for diagnosis of syringomyelia is an MRI of the cervical (neck) and/or thoracic (middle back) spine.

Treatments for Syringomyelia include medications for nerve pain, or in some cases surgery. If the cause of syringomyelia is the Chiari malformation, the treatment is often decompression surgery to make more space at the base of the skull.

Neuro-monitoring

Neuro-monitoring, or Intra-operative monitoring is a procedure that involves placing small electrodes (wires) on various places (such as hands/arms/feet/scalp, etc). The electrodes are generally placed while the patient is asleep (under general anesthesia), but the person may notice a small tender area where the needle electrode was. There may also be an electrode placed in the ear canal, much like the microphones used with a music player. Impulses are sent through the electrodes to stimulate various nerves, and the response is monitored on the computer screen.

The technician is in the operating room during the surgical procedure and monitors the nerve activity via computer. The nerve activity is sent by computer to a specialist (usually a Neurologist), who will monitor your sensory and motor function continuously during the surgical procedure.  If any changes occur during the procedure, the specialist notifies the technician, who notifies the surgeon immediately.

Intraoperative monitoring can help ensure that if there is any abnormal activity in the system being monitored, the surgeon will be notified immediately. Though not needed in all neurological surgeries, this additional safeguard may help reduce the risk of nerve injury in some cases.

Dim lights at dusk for better sleep

Sleep is fundamental to good health. Sleep impacts the quality of your day, and what happens during the day impacts the quality of your sleep. While many factors affect sleep, one we can control, yet often don’t, is the intensity of light we are exposed to before bedtime.

As we saw in The End of Night, the development of the light bulb and alternating current allowed us to effectively eliminate night at will. Since most of us prefer to get a good night’s sleep, recall during the Paleolithic the slow decrease in light intensity at dusk prepared the brain for sleep, primarily by the secretion of melatonin. Today, we often keep the room lights on until bedtime and then, once turned off, expect to fall asleep effortlessly. For millions of Americans, the failure to adequately prepare the brain results in nonrestorative sleep.

According to EurekAlert, the Journal of Clinical Endocrinology & Metabolism will publish an article comparing normal room light versus dim light on the secretion of melatonin:

In this study, researchers evaluated 116 healthy volunteers aged 18-30 years who were exposed to room light or dim light in the eight hours preceding bedtime for five consecutive days. An intravenous catheter was inserted into the forearms of study participants for continuous collection of blood plasma every 30-60 minutes for melatonin measurements. Results showed exposure to room light before bedtime shortened melatonin duration by about 90 minutes when compared to dim light exposure. Furthermore, exposure to room light during the usual hours of sleep suppressed melatonin by greater than 50 percent.

Lead author Joshua Gooley, PhD concludes:

Our study shows that this exposure to indoor light has a strong suppressive effect on the hormone melatonin. This could, in turn, have effects on sleep quality and the body’s ability to regulate body temperature, blood pressure and glucose levels.

While it is not practical to dim the lights for 8 hours prior to sleep, at least an hour of dim light should help those with difficulty initiating sleep. A good solution is to install dimmer switches in the rooms most frequented at dusk and a dimmer switch on the nightstand lamp. As we create our own modern Paleolithic, maybe homes in the future will be programmable to dim electric lighting automatically at a set time and rate.