A spinal headache is a distinct form of head pain, formally known as a post-dural puncture headache. Unlike common headaches, its defining characteristic is a positional component: pain intensifies when a person sits or stands upright and improves when lying flat.
The Underlying Mechanism
The root cause of a spinal headache lies in the delicate balance of fluids within the central nervous system. The brain and spinal cord are encased within protective layers called meninges, the outermost being the dura mater. Cerebrospinal fluid (CSF) circulates within the dura mater, cushioning and protecting these structures.
CSF also maintains a specific intracranial pressure within the skull. When the dura mater is breached, CSF can leak, reducing the fluid volume and lowering intracranial pressure.
With less fluid support, the brain can subtly shift downward. This displacement stretches pain-sensitive structures, such as blood vessels and nerves at the base of the brain, causing the characteristic headache pain. The positional nature of the headache, worsening when upright and improving when lying down, directly correlates with the effect of gravity on the brain when its buoyant support is diminished.
Medical Procedures as Causes
Medical procedures are the most frequent cause of spinal headaches, developing after intentional or accidental puncture of the dura mater leads to cerebrospinal fluid (CSF) leakage. Lumbar punctures, often called spinal taps, are a prime example. During this diagnostic procedure, a needle is inserted into the lower spine to collect a sample of CSF or to administer medication. Even with careful technique, the tiny hole created by the needle can allow CSF to continue leaking, initiating a spinal headache.
Epidural anesthesia, frequently used for pain relief during childbirth or surgery, is another common cause. While the epidural needle is intended to remain outside the dura mater in the epidural space, an accidental puncture of the dura, sometimes referred to as a “wet tap,” can occur. This unintended dural perforation allows CSF to escape, leading to the development of a spinal headache.
Spinal anesthesia, where medication is injected directly into the CSF within the dura, also involves puncturing the dura mater. Although needle designs have improved, reducing the incidence, the procedure inherently carries a risk of CSF leakage and subsequent headache. Approximately 1% to 5% of individuals receiving epidural or spinal anesthesia might experience a spinal headache.
Other Contributing Factors
Beyond medical procedures, other less common factors can also lead to a spinal headache. Accidental dural tears can occur during certain surgical procedures involving the spine, creating an opening for cerebrospinal fluid to leak. While infrequent, such tears can result in the same mechanism of reduced intracranial pressure and subsequent headache.
Traumatic injuries, such as those sustained in falls or accidents that impact the spine, can also cause a dural tear and a CSF leak. Even without a direct puncture from a medical instrument, significant force or injury to the spinal column may compromise the integrity of the dura mater. In some instances, spinal headaches can arise spontaneously, without any identifiable medical procedure or trauma. These “spontaneous CSF leaks” are thought to result from pre-existing weaknesses in the dura or other underlying conditions.
Certain risk factors can increase an individual’s susceptibility to developing a spinal headache. These include a history of headaches, being female, and having certain connective tissue disorders that might affect the strength of the dura mater. Younger individuals, particularly those between 18 and 30 years old, also appear to have a slightly elevated risk.