Brain implant enables ALS patient to communicate for nearly two years, generating 2 million words

A brain-computer interface has enabled Casey Harrell, a 48-year-old man with ALS, to communicate at 56 words per minute for nearly two years from home. The device, which translates neural signals into text, has allowed him to continue working and reconnect with family. The system's success marks a major step for BCI technology, though experts note that invasive surgery and potential device variability remain challenges.

Casey Harrell ALS speech BCI

• ▪The device has allowed Harrell to continue his job in climate advocacy, send emails, and communicate with his family
• ▪Casey Harrell, a 48-year-old man with amyotrophic lateral sclerosis (ALS), has used a brain-computer interface (BCI) at home for nearly two years
• ▪A study on Harrell's BCI use, published in Nature Medicine on June 15, 2026, represents the longest-running data set for such an implant
• ▪The BCI translates Harrell's neural activity into text, allowing him to communicate at an average speed of 56 words per minute

Phoneme decoding neural algorithms

• ▪The BCI's vocabulary was expanded to 125,000 words with 97.5% accuracy
• ▪The system decodes speech by mapping brain activity to the 39 phonemes of American English, then converting phonemes to words
• ▪In July 2023, surgeons implanted 256 microelectrodes in Harrell's speech motor cortex during a five-hour operation

Independent home system operation

• ▪Harrell has used the device for over 3,800 hours at home without researchers present, with care partners able to connect it for him
• ▪Over a period of nearly 23 months, Harrell used the BCI at home on 364 of 397 days, generating 183,060 sentences

Privacy mode cursor control

• ▪The BCI also detects neural signals for hand movements, enabling Harrell to control a computer mouse to browse the web and send messages
• ▪The system includes an optional 'privacy mode' that stops data transmission to researchers and a 'profanity filter'

ALS patient device variability

• ▪Experts caution that the device's long-term success may not be replicable due to factors like brain degeneration or scar tissue formation
• ▪A previous BCI patient with ALS had their device stop working after seven years, possibly due to brain degeneration

Invasive surgery adoption barriers

• ▪The requirement for invasive brain surgery and hospital stays may be a barrier to adoption for many ALS patients, according to some researchers
• ▪The electrodes are connected to external computers via two titanium pedestals attached to Harrell's skull