Thank you for that Haresh,
You state, "Inversion can reduce back pain, decompress the spine." How would a student decompress the spine while practicing Sirsasana or Sarvangasana? These asanas are just two examples of severe compression in the cervical vertebrae. Depending on the student chronic cervical nerve root compression can occur at any age. Why go asking for trouble?
Chronic cervical nerve root compression refers to nerve irritation caused by damage to the disc between the cervical vertebrae, so that the disc presses on the nerve root as it leaves the bony spinal column. This occurs because of wear and tear or injury, or both and can lead to painful burning or tingling sensations in the arms.
The nerve roots that arise from the spinal cord in the neck can be affected by sudden stretching or compression, and pain and spasm in the muscles of the neck tend to occur as a result. Usually neck movements are painful and restricted, and the pain may radiate to the shoulder region.
Inverted yoga posture is not for everyone. If you have any of the following health conditions, please do not invert without the approval of your licensed physician. This is not a complete list. It is intended for your reference.
Osteoarthritis: The discs and the joints that stack the vertebrae (facet joints) are subject to wear and tear over time (degenerative changes). If we focus only on the cervical spine - Degeneration of the cervical discs is medically referred to as cervical spondylosis and can often be noted on X-rays or by MRI scanning as a narrowing of the normal disc space between the vertebrae. It would take a manual to list all of the potential spinal problems. There are many more spinal conditions and this is just one example.
Anti-Coagulants (Use of): Blood-thinning drugs such as coumadin or aspirin to reduce clotting of the arteries and blood vessels. The use of anti-coagulants signals people at risk for circulatory problems.
Bone weakness, recent fractures, skeletal implants: Inversion may exacerbate these conditions.
Conjunctivitis - (Pink eye): An inflammation of the transparent membrane that covers the front surface of the eyeball and the inner surface of the eyelids caused by bacterial or viral infection.
Glaucoma: A condition of elevated pressure within the eye because of an obstruction of the outflow of the clear, watery fluid circulating in the chambers of the eye. The resulting pressure (which is imperceptible without an eye exam) kills cells in the optic nerve, which can lead to a gradual loss of vision.
Heart / circulatory disorders: Any condition involving the circulatory system.
Hiatal hernia, ventral hernia: A hiatal hernia occurs when intra-abdominal pressure increases cause a portion of the stomach to move into the chest cavity through a weakness in the diaphragm. A ventral hernia develops at the site of previous surgery, usually along vertical incisions. It may also result from weakness in the abdominal wall.
High blood pressure, hypertension: A common disorder in which the heart is pumping blood through the circulatory system with a force greater than that required for normal blood flow. An elevated blood pressure which exceeds 140/90.
Middle ear infection: The middle ear helps equalize air pressure in the ear. A person may feel discomfort or disorientation during inversion.
Obesity (extreme): In some people obesity can be associated with the undetected onset of many of the circulatory and eye problems mentioned above. The weight capacity of each of the inversion products should not be exceeded.
Pregnancy: Pregnant women should exercise caution when inverting.
Retinal detachment: A separation of the retina, the thin, delicate membrane covering the rear portion of the eye, from the optic nerve. Usually results from a hole in the retina that allows the vitreous humor fluid to leak. Treatment is almost always surgical. A retinal hemorrhage, in most cases, can heal by itself.
Spinal injury: Any severe spinal cord trauma requires a person to consult their physician before inverting.
Stroke: Occurs when a blood vessel in the neck or brain becomes blocked or when a vessel in the brain bursts open. Symptoms include paralysis, difficulty speaking, memory loss, and impaired thought processes.
Transient ischemic Attack: Often called a "ministroke," a TIA occurs when the blood supply is temporarily interrupted to a part of the brain due to a blockage. Often precedes the onset of a full stroke, and requires immediate action.
Hari Om Tat Sat