Note37  Use the following fifth-digit subclassification with categories 851-854:

                        0          unspecified state of consciousness
                        1          with no loss of consciousness
                        2          with brief [less than one hour] loss of consciousness
                        3          with moderate [1-24 hours] loss of consciousness
                        4          with prolonged [more than 24 hours] loss of consciousness and
                                    return to pre-existing conscious level
                        5          with prolonged [more than 24 hours] loss of consciousness,
                                    without return to pre-existing conscious level

Use fifth-digit 5 to designate when a patient is unconscious and dies before regaining consciousness, regardless of the duration of the loss of consciousness

                        6          with loss of consciousness of unspecified duration
                        9          with concussion, unspecified