This is considered to relate to a nutrient deficit in those patients in whom this sign is seen: Keith Lamont, who first drew attention to the Black Line Phenomenon, has found that administration of vitamin E, bioflavonoid complex and homoeopathic ferum phosphate will correct this deficiency.

Bertrand DeJarnette D.C. the developer of sacrocranial technique, writes extensively on the subject of the 'red reaction'-

He describes how he initially makes assessments of patients (partly based on blood pressure readings) into various categories, during which process he has them treated in order to alter the relative oxygenation levels which are assumed on the basis of these categories. None of these methods are pertinent to this survey of skin reactions, but are a necessary preamble to his descriptions, which would be confusing otherwise. In a ‘type 1’ patient, who has received the appropriate preliminary attention as outlined ('carbon dioxide elimination technic'):

'Sit or stand immediately behind the patient facing the patient's back. Have the patient bend slightly forward. Be sure the light is even on the patient's back to avoid shadows. Place the index and middle fingers of your right hand upon the 7th cervical vertebra, having the two fingers about an inch lateral from the spine of the 7th cervical vertebra. Keep the fingers evenly spaced as you go down the spine, so each line is as straight as possible. For the 'Type 1' patient (normal BP after appropriate techniques) use a light touch. To produce an even pressure of both fingers on the back they may be fortified by placing the fingers of the left hand over them. As you go down the spine, your pressure will be just hard enough to cause the fingers to dent the skin.

Now draw your fingers down the spine very quickly ending at the coccyx. Step back and watch the reaction. A red line will usually appear all the way down the spine. This soon starts to fade and the fading is what you must watch. The area that appears Reddest as this fading starts, is the major [lesion] for this patient and should be marked with a skin pencil. You will often notice on this type of patient that the major area is much wider than any other area of your lines down the back. This is caused by tissue infiltration'.

The 'Type 2' category patient will have slightly high blood pressure after DeJarnette's preliminary treatment. After adopting the same starting position:
'Making a firm pressure, draw fingers down the spine, with a fairly slow motion. You should be able to count to 15 while drawing the fingers from the 7th cervical to the coccyx, by counting steadily. With a good light on the back, the results should show a line which becomes red, some portions brighter and some very faintly coloured. Now watch the lines fade. The area which shows the Whitest is marked as the major [lesions] for this is the most anaemic spinal muscle area. It will be paler than any portion of skin on the patient's body.'

Moving next to the final category which interests us in this survey, (patients with high blood pressure) DeJarnette asks that you adopt the same start position and then: 'Making heavy pressure, come down the spine slowly, counting 20 as you go from 7th cervical to coccyx. Now watch the reaction. The line that shows the Whitest is the major [lesion]. In this type the blood pressure is over 180 (systolic) the whitest area shows a waxy, pale colour and may persist for several minutes.'