Note50  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