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What is Post-dural-puncture headache and explain in detail?
Post-dural-puncture headache (PDPH) is a complication of puncture of the dura mater (one of the membranes around the brain and spinal cord). The headache is severe and described as "searing and spreading like hot metal", involving the back and front of the head and spreading to the neck and shoulders, sometimes involving neck stiffness. It is exacerbated by movement and sitting or standing and is relieved to some degree by lying down. Nausea, vomiting, pain in arms and legs, hearing loss, tinnitus, vertigo, dizziness and paraesthesia of the scalp are also common.PDPH is a common side effect of lumbar puncture and spinal anesthesia. Leakage of cerebrospinal fluid causes reduced fluid levels in the brain and spinal cord. Onset occurs within two days in 66% of cases and three days in 90%. It occurs so rarely immediately after puncture that other possible causes should be investigated when it does.Using a pencil point needle rather than a cutting spinal needle decreases the risk. The size of the pencil point needle does not appear to make a difference. PDPH is estimated to occur in between 0.1% and 36% people following dural puncture.

Signs and symptoms
PDPH typically occurs hours to days after puncture and presents with symptoms such as headache (which is mostly bi-frontal or occipital) and nausea that typically worsen when the patient assumes an upright posture. The headache usually occurs 24–48 hours after puncture but may occur as many as 12 days after. It usually resolves within a few days but has been rarely documented to take much longer.

Pathophysiology
PDPH is thought to result from a loss of cerebrospinal fluid into the epidural space. A decreased hydrostatic pressure in the subarachnoid space then leads to traction to the meninges with associated symptoms.

Diagnosis
Differential diagnosis
Although in very rare cases the headache may present immediately after a puncture, this is almost always due to another cause such as increased intracranial pressure and requires immediate attention.

Prevention
Using a pencil point rather than a cutting spinal needle decreases the risk. The size of the pencil point needle does not appear to make a difference, while smaller cutting needles have a low risk compared to larger ones. Modern, atraumatic needles such as the Sprotte or Whitacre spinal needle leave a smaller perforation and reduce the risk for PDPH. However, the evidence that atraumatic needles reduce the risk of post-dural puncture headache (PDPH) without increasing adverse events such as paraesthesia or backache is moderate-quality and further research should be done.Morphine, cosyntropin, and aminophylline appear effective in reducing post dural puncture headaches. Evidence does not support the use of bed rest or intravenous fluids to prevent PDPH.

Treatment
Some people require no other treatment than pain medications and bed rest. A 2015 review found tentative evidence to support the use of caffeine. Vigorous hydration is routinely encouraged in postpartum patients as a noninvasive, low-risk therapy.Pharmacological treatments as; gabapentin, pregabalin,  neostigmine/atropine,  methylxanthines, and triptans