He wrote letters to Menuhin in April and June 1944 to agree on minor changes to make the Sonata easier to play.
After a section where the melody is accompanied quietly with fast running notes, it returns as a series of chords, alternately played with the bow and plucked in inversion.
The Presto alternates between a very quiet, fast, bumblebee-like passage played with a mute, and a cheerful melody.
Bartók originally wrote the rapid passages in quarter-tones, but many violinists choose to perform a version, suggested by Menuhin, that only uses the standard 12 notes of Western classical music.
The Solo Sonata presents violinists with many difficulties and uses the full gamut of violin techniques: several notes played simultaneously (multiple stops), artificial harmonics, left-hand pizzicato executed simultaneously with a melody played with the bow, and wide leaps between pitches.