A YOUNG man lies unconscious on the table, his head clamped firmly in place. His eyes are closed. The hair over his left temple has been shaved.
I鈥檓 in the operating room at University Hospital Zurich in Switzerland with neurologist Thomas Grunwald, who has diagnosed 22-year-old Jeremy K眉nzler with drug-resistant temporal lobe epilepsy. His symptoms during fits suggest that the seizures begin in the left temporal lobe. Often, this condition can only be treated by surgically removing the errant brain tissue. Unfortunately, brain scans have revealed nothing that would point to the source of K眉nzler鈥檚 seizures 鈥� no obvious tumour, scar or lesion.
In ordinary circumstances, K眉nzler would have to undergo exploratory brain surgery. But instead of this drastic operation, Grunwald is pioneering a technique to pinpoint the problem area. He has asked neurosurgeon Niklaus Krayenb眉hl to implant electrodes inside K眉nzler鈥檚 skull: a grid electrode over his left temporal lobe, and two strip electrodes beneath the left and right lobes, used to monitor activity bilaterally in the hippocampi and amygdalae. Once they are in place, Grunwald will record brain signals in real time during seizures and use the information to try to identify the epileptogenic tissue.
Advertisement
It鈥檚 my first time inside an operating room. I鈥檓 anxious, as I have been told not to touch a thing for fear of contamination, especially the giant surgical microscope covered in clear, sterile plastic. 鈥淭he nurses are very strict,鈥� says Grunwald. 鈥淚f you touch this, even with your head, they get really angry.鈥�
Krayenb眉hl swiftly cuts through the scalp and the temporal muscle, cauterising and clamping the edges with plastic clips to prevent bleeding, and peels the tissue back to reveal the skull bone. He drills two holes in it and saws out a circular piece. The sounds remind me of the dentist. Wisps of smoke rise from the heat of metal against bone. The surgeon removes the bone flap, exposing the meninges 鈥� the layers of membrane that envelop the brain. To avoid any chance of infection, the nurse helps Krayenb眉hl slip on a fresh pair of gloves.
He then parts the first, thick layer of the meninges, the dura mater. Below it is the arachnoid layer, beneath which flows the cerebrospinal fluid bathing the brain. Krayenb眉hl makes tiny cuts in the arachnoid, to let the CSF ooze out and relieve the pressure. 鈥淥therwise the brain will pop out like a mushroom,鈥� he says.
鈥淲e let the fluid ooze out to release the pressure, otherwise the brain will pop out like a mushroom鈥�
Krayenb眉hl is working through the microscope and what he鈥檚 seeing is projected onto a large screen. The brain tissue is clearly visible: a whitish convoluted surface suffused with blood vessels. Krayenb眉hl works quickly to slip the electrodes, just 0.7 millimetres thick, between the dura mater and the arachnoid. Once he鈥檚 done, he works in reverse, sewing up the dura mater, reattaching the bone with titanium clips, suturing the muscle and scalp. The electrode cables, which exit the skull through the two holes, are drawn out through tiny cuts in the scalp.
The surgical staff then turn the patient over and start working on the right side of the brain.
Two days later, I visit K眉nzler, recovering at the Swiss Epilepsy Centre across town. He has two black eyes from a surgery-induced haematoma, but they still have a twinkle. His head is heavily bandaged. K眉nzler鈥檚 English is limited, so Grunwald translates.
Though K眉nzler鈥檚 anti-epileptic medication barely has an effect on the frequency of his seizures, it has been reduced to let more occur. 鈥淚f we are lucky, then we鈥檒l get seizures maybe tonight or tomorrow,鈥� Grunwald tells me. K眉nzler laughs. He knows enough English to get what Grunwald is saying. I ask him if he鈥檚 afraid of the seizures. 鈥淚鈥檓 not afraid, as long as it鈥檒l help me,鈥� says K眉nzler.
It is Grunwald鈥檚 job to analyse the intracranial EEG signals and locate the source of the seizures. There is no automated process to help him sift through the data, just his own skill and experience. 鈥淚f you record 24 hours of EEG, then you have to look at 24 hours of EEG,鈥� says Grunwald. 鈥淓very second of it.鈥� He hopes they鈥檒l show that K眉nzler鈥檚 seizures are in the left temporal lobe and far away from the Wernicke鈥檚 area that is involved in language, which he cannot remove.
This article appeared in print under the headline 鈥淚nside the brain, searching for seizures鈥�
