Art critic Tom Lubbock developed a brain tumour which estranged him from language in subtle and unpredictable ways. The Guardian has a stunning article where the writer describes how his relationship with language was altered as the tumour encroached upon his brain.
It is one of the most powerfully nuanced accounts of language impairments I have yet read and you can feel the years of art-criticism experience poured into Luddock’s analysis as he charts the effects of the glioblastoma tumour on his temporal lobe.
For a period, suddenly, I cannot speak (or read aloud) any words except the most short, simple, basic. They are fine. And all the rest, the more complex ones, come out as a kind of garbled gobbledygook or jabberwocky. Yet the stress of all the words and sentences – sense or nonsense – is equally and perfectly accurate. I know what I mean to say and to a hearer what I say moves fluently, though in and out of meaningfulness. Simple and comprehensible words punctuate a sequence vocalised out of nonsense.
It is a permanent mystery how we summon up a word. Where are these connections located in the mind? How do we know how we do it and get it right? This mystery only becomes evident when our ability to summon up our words fails.
There are many vivid passages in the piece but I was particularly struck by the most recent October 2010 entry. It is genuinely poetry in the truest sense as it captures the state of the author’s fractured language in both its content and form while subtly communicating the emotional resonance of the changes.
Link to Tom Lubbock on when words slip away (thanks @bakadesuyo).
Mind Hacks 
I’ve been a reader of mindhacks for a few years, and I’ve read countless stunning and mindblowing posts, but this, for me, is tops.
I was stricken with awe at the poetic flow of words that Tom still managed to summon up, even as his language ability declined. His last entry almost brought me to tears; tears of both sadness and joy.
I think accounts such as this have important implications for how we think of the connection between language and cognition and consciousness. Intuitively, language seems in many ways essential to our ability to order, interpret, and categorize information. To understand our private subject experiences and explain them to others, we tend to rely on language (at least, when not expressing them through visual, musical, or other forms of art). Language seems… well, almost necessary.
Yet, while for Tom, “[…] language to describe things in the world is very small, limited” his thoughts remain, “[…] vast, limitless and normal, same as they ever were.”
I couldn’t put it any better myself, intact language ability and all.