How a wearable OPM-MEG helmet located a child’s language area before laser epilepsy surgery at Fudan

Quentir Medicine Monitor

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An eight-year-old boy in Shanghai had a seizure focus in the part of the left frontal lobe that textbooks call Broca's area, the classical seat of spoken language. His team at the Children's Hospital of Fudan University located both the focus and his language function with a 128-channel helmet of optically pumped magnetometers, then destroyed most of the focus with a laser. Six months later his seizures were controlled and his speech was intact.

The case report, by Yuanfeng Zhou, Yanjiong Zhang and colleagues in the hospital's neurology, neurosurgery and radiology departments, with coauthors from Beihang University and Fosun MedTech, appeared in Acta Epileptologica on 3 May 2026. It describes one child with drug-resistant epilepsy and one presurgical workup. Its authors present it as a feasibility demonstration, and they call for clinical trials to test the diagnostic value of the method in children.

The clinical problem is familiar to every epilepsy surgery program. Removing or burning tissue in a language region can cost a child the ability to speak, so surgeons want a map of where language actually sits before they operate. The usual tools for presurgical language mapping are functional MRI and the Wada test, an injection of an anesthetic drug into one carotid artery to silence one hemisphere at a time. This boy could use neither.

His seizures began at five years and nine months of age, with clapping of both hands, repeated blinking and stiffening of the arms. Five antiseizure drugs, oxcarbazepine, levetiracetam, lacosamide, clonazepam and perampanel, brought four months free of seizures at best. At six years and five months the seizures returned in clusters of one to more than ten a day, and he was diagnosed with drug-resistant epilepsy.

Three tests pointed to the same spot. MRI showed abnormal signal in the opercular part of the left inferior frontal gyrus, PET showed reduced metabolism there, and video EEG recorded focal seizures starting in the left frontal region. Trio whole-exome sequencing of the child and both parents found no explanatory genetic variant, and his full-scale IQ on the Wechsler scale was 119. The hospital's refractory epilepsy team decided the focus should be removed or thermally coagulated. The difficulty was its location: the opercular part of the inferior frontal gyrus corresponds to Brodmann area 44, which with the neighboring triangular part, area 45, makes up the classical Broca's area.

According to the report, both standard tests were refused: the Wada test because it is invasive, and functional MRI because the boy tolerated the scanner's loud noise poorly. That left OPM-MEG as the only source of quantitative data on where his language function lay.

Magnetoencephalography, or MEG, measures the faint magnetic fields produced by electrical activity in the brain. The Fudan system, the Marvel MEG 128 from Beijing X-Magtech Medical Technologies, fixes 128 sensors to a child-size helmet. Each sensor is an optically pumped magnetometer: a laser prepares the quantum spin states of atoms in a small glass vapor cell, and a magnetic field changes how those atoms absorb light. The system sits inside a magnetic shielding enclosure that avoids building a full shielded room, and the authors report sensor noise below 15 femtotesla per square-root hertz between 10 and 100 hertz.

The boy had two sessions. The first was a 60-minute resting recording, eyes closed and lying still, to capture epileptic discharges. Three MEG technicians reviewed the recording and marked the spikes, and 20 fitted dipoles placed their sources mainly in the middle frontal gyrus, the inferior frontal gyrus and the insula. Those locations agreed with the Broca's area outline, the averaged spike maps and the low-metabolism zone on PET.

The second session tested language. In each of 150 trials, a Chinese noun appeared for three seconds after a two-second rest, and the boy silently thought of a matching verb, so that "football" called up "kick." The team measured the drop in beta-band brain rhythm during this task and projected it onto his own MRI with a beamformer, a standard method for locating the sources of MEG signals. The strongest activity sat in the left hemisphere, in the orbitofrontal cortex, the insula and the superior temporal gyrus. The report describes minimal overlap with the epileptic focus, and at a display threshold of 60 percent of the maximum it found no overlap with the classical Broca's area on the brain surface.