A vestibular nerve tumour can impact hearing, facial expression and balance, making it the top stress-inducing procedure for neurosurgeons
This picture has been used for representational purposes
I can't seem to hear well from the right ear," said a concerned 28-year-old airhostess poised gracefully in front of me. "Initially, I thought it was because of the ambient hum of the airplane, but now I'm convinced it's a problem because I find it hard to decipher what people are saying on the phone as well. I've also noticed a bothersome buzzing in my head as if a bee is bouncing off the walls within my skull with nowhere to go. There is also a subtle sway in my gait toward the right, but I'm not sure if I'm imagining it. The airline company doctor got me to do an audiogram and MRI, and has asked me to see you with these results."
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I asked her to follow my index finger with her eyes by keeping her head straight, and noticed an abnormal jerk in her gaze when she looked to the right. Quick coordinated movements of her right hand lagged a little in dexterity when compared to her left side. When I made her walk in one line, heel to toe, the test made famous by the police to see if you're under the influence of alcohol, she stumbled, shuffling towards the right.
The MRI showed a 4.2-cm ice cream cone-shaped tumour arising from the vestibular nerve, one of the 12 cranial nerves that leads directly from the brain to various parts of the head and neck, and the one concerned with equilibrium. This is in proximity to the auditory nerve and hence, the intricate association of balance with hearing. The other nerve that is at close quarters in this byzantine anatomy is the facial nerve that controls all the muscles of facial expression. I made her clench her eyes tightly and puff her cheeks to check for facial weakness. I explained that given the size of the tumour, she needed surgery. If it was around 2.5 cm, we could try and zap it with radiation. The only concern with surgery was that because the tumour is adjacent to an already stretched out facial nerve, she would experience facial weakness after surgery, but it should, hopefully, recover over time.
"Hopefully?" she stopped me. "I won't have a job if half my face is paralysed," she stared back almost angrily, unable to comprehend the association between a vestibular nerve tumour, hearing, and facial dysfunction. After about an hour of explaining the complexities of the surgery of this nature, we agreed to remove as much of the tumour as was safely possible without any risk to the facial nerve. If parts of the tumour remained, we would consider radiation at a later stage.
After induction of general anaesthesia, we connected electrodes to the facial muscles to get real-time feedback while we peeled off the tumour. A tumour of this size is often imperceptibly merged with the nerves, even a multi-fold magnification and intense illumination of the microscope makes it difficult to discern the difference between a thinned-out nerve and tumour capsule. We often joke that attempting to simply spot the nerve is enough to cause a facial weakness, let alone the outcome after handling an already compromised nerve for a few hours.
We debulked a large amount of the tumour using an ultrasonic aspirator, which gobbled up chunks of it, giving us some space to be able to identify normal anatomy. We then used a high-speed drill to core out the internal auditory canal, the point of origin of the tumour, and gently rolled it over the vestibular-auditory complex of nerves, while the electrophysiologists in the rooms constantly alerted us of the integrity of the nerve.
We identified the facial nerve slapped thin over the anterior surface of the tumour, a far cry from its normal pristine round self that we see when we expose this region for other conditions. Removing the last part of this tumour is the most daunting because of the maximum adhesiveness of the tumour to the nerves here. Four hours of diligence can be nullified in four seconds.
The girl's face flashed in front of me. The questions she had fired at me, played in my head. I held the last part of the tumour with a cup-forceps while dissecting it off the nerve with another pointed forceps, hoping it wouldn't snap. The beating of my heart was a drum and in competition with the cantankerous sound of the facial nerve monitor, which went off like the firing of a soldier on the border before martyrdom.
Some time ago, a study was conducted at the All India Institute of Medical Sciences, where they hooked up neurosurgeons to monitors while performing this operation. They recorded an astronomical rise in both the pulse and blood pressure of neurosurgeons during the crucial parts of the procedure. They concluded that, "Neurosurgery can induce a significant hemodynamic stress malresponse in the operating surgeon that appears to be greater than that induced by vigorous exercise. The correlation of this occupational hazard to long-term health and longevity remains to be studied." The monitor silenced only after we removed the tumour completely, the nerve hanging in there like an overburdened clothesline, weary but intact. Despite the physiological preservation of the nerve, her face was weak for a few weeks, but I was confident it would improve.
When she returned in six months, I asked my neurologist to guess the side we had operated on. He couldn't tell. She had recovered completely and was back to work. She delightfully smiled through her perfect teeth with tears in her eyes, reminding me of a beaming Julia Roberts.
The writer is practicing neurosurgeon at Wockhardt Hospitals and Honorary Assistant Professor of Neurosurgery at Grant Medical College and Sir JJ Group of Hospitals. You can reach him at [email protected]
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