PDPH

Question 1

What are the symptoms of PDPH?

Answer 1

headache worse upright better lying flat, associated symptoms in up to 70% of pts: neck stiffness, photophobia, nausea, subjective hearing symptoms, visual changes or backache

Question 2

What’s the potential mechanism of PDPH?

Answer 2

CSF leakage > production causes low CSF pressure, acute cerebral venous distension–> headache. Traction on intracranial structures may have a role.

Question 3

What’s the incidence of PDPH after spinal anaesthesia? LP? labour epidural?

Answer 3

<3%, depending on type & size of needle
11% (if standard traumatic needle used), 4.2% with pencil-point, NNT 15 w no difference in success of the LP on first attempt
UDP occurs in 1.5% & PDPH occurs in 50-80% of pts with UDP (ie. PDPH after labour epidural 1:100-1:200)- rates with CSE are similar

Question 4

What are some risk factors for PDPH?

Answer 4

Patient: young female, pregnant, low bmi. Labour & 2nd stage pushing, PHx headaches, age 18-50
Procedure: cutting tip, larger gauge (although this correlation hasn’t been found for obstetric spinals), placement of a spinal in sitting vs lateral and increased number of passes also incr risk PDPH. Evidence for paramedic & decreased operator experience are conflicting, as is use of LOR to saline vs air (onset of headache may be sooner w air likely related to pneumocephalus vs low CSF pressure)

Question 5

What’s the evidence for methods to prevent PDPH after UDP?

Answer 5

Bed rest has NOT been shown to reduce risk of PDPH in meta-analyses & but it may reduce intensity of headache.
Abdominal binder has little evidence but theoretical advantages, low risk & women may like wearing one anyway.
No strong evidence that any drug regimen prevents, although ondansetron may have benefit, as may epidural morphine (ondansetron may trigger migraine in susceptible pts).
Prophylactic EBP- if the pt has an epidural catheter in place after a known UDP, prophylactic EBP has been done before catheter removed- it doesn’t reduce incidence of PDPH but may decrease the intensity &/or duration of symptoms
Placing an intrathecal catheter after UDP has not been established in RCTs to reduce the risk of PDPH but they may reduce the need for multiple epidural attempts & risk of subsequent additional UDP. Also, they may have a higher rate of failed labour analgesia cf re-sited epidural.

Question 6

When do PDPH usually present?

Answer 6

90% present within 72hrs after a dural puncture. Onset has rarely been reported up to 2 wks later.

Question 7

When do PDPH usually resolve?

Answer 7

Most resolve within 7-10 days if untreated, 50% resolve by 5 days.

Question 8

What are some neuroimaging findings with PDPH?

Answer 8

Small ventricles, brain sagging, engorged cerebral venous sinuses- similar findings to spontaneous intracranial hypotension- (although neuroimaging isn’t indicated unless excluding alternate diagnoses)

Question 9

What are some differential diagnoses for PDPH? Main signs warranting imaging?

Answer 9

migraine, PET, spontaneous intracranial hypotension, meningitis, subdural haematoma, cerebral venous thrombosis, reversible cerebral vasocontriction syndrome (thunderclap headaches +/- neuro Sx +/- seizures, due to cerebral artery vasospasm), posterior reversible encephalopathy syndrome (swelling). Imaging if focal neurological deficits, altered consciousness, seizures, fever, headache prolonged (>5/7, more suspicious for haemorrhage), not improved or worsened by blood patch.

Question 10

What are contraindications to epidural or epidural blood patch?

Answer 10

Pt refusal, allergy to anything administered, coagulopathy, systemic infection or local infection over site of insertion. HIV theoretical risk for CNS infection but HIV is a neurotropic virus, infecting CNS @ its early stages & no adverse effects have been reported with EPB in HIV.

Question 11

What are the instructions after epidural blood patch?

Answer 11

Lie flat (or to a max 30 degrees) for 1-2hrs with minimal movement, avoid heavy lifting or strenuous activity for 24hrs (limited evidence to support this), taper analgesics to limit risk of rebound headaches.

Question 12

How many sterile fields are required for epidural blood patch? At what level is the epidural inserted? What do first (epidural or blood draw)? How much blood drawn?

Answer 12

2- one for epidural & one for blood draw. Do the epidural first (unless expected difficult blood draw), at same interspace as the dural puncture- if not known, do at lowest mark as more likely to spread cephalad than caudal. 20mL venous blood, injected slowly, stop if pt experiences significant pain or pressure.

Question 13

What are the complications of epidural blood patch?

Answer 13

failure of technique, additional dural puncture, infection, subdural abscess, epidural haematoma & temporary/permanent nerve damage (eg. facial nerve palsies, spastic paraparesis, caudal equina syndrome), BACKACHE (30% of pts, usually resolves within 48hrs), misplacement of blood causing spinal subdural haematoma or intrathecal injection and arachnoiditis.

Question 14

Which intervention is considered definitive treatment for PDPH & what’s it’s success rate?

Answer 14

Epidural blood patch- 65-98% effective for first & similar rate for second, if required. Usually relief within secs to mins of injection of the blood.

Question 15

What’s considered appropriate Rx for PDPH?

Answer 15

Depends on severity, impact on ADLs & shared decision-making with pt.
Mild: PO +/- IV hydration, simple analgesia & antiemetics
Debilitating: epidural blood patch considered definitive Rx.

Question 16

What’s the evidence for caffeine? Complications? What’s the general advice?

Answer 16

Limited- 2x rcts approx 40 pts each, one showed 300mg po caffeine cf placebo reduced pain scores @ 4hrs but no difference in pain scores @ 24hrs or need for EBP. Another compared 500mg IV caffeine w placebo, showing early headache relief but no change in pain scores @ 24hrs or need for EBP.
There are reports of grand mal seizures after IV caffeine for PDPH.
Pts who usually drink caffeine should keep up their regular intake & avoid withdrawal- equivalent of 300mg/mane is 1.5 espresso shots. Pts who don’t usually have caffeine could have 300mg tablet PO mane for 3 days to see if effect- warn that may make them feel anxious/palpitations & may make baby more restless.

Question 17

What’s the sphenopalatine ganglion & what’s the mechanism & potential benefits of bilateral trans nasal sphenopalatine ganglion block?

Answer 17

An extra cranial parasympathetic ganglion lying in the pterygopalatine fossa behind the middle nasal turbinate. It has connections with nasal branch of trigeminal nerve, Blocks SNS, PSNS & somatic sensory nerves with topical local anaesthetic. Easy, low-risk, generally provides temporary relief (4-18hrs) but may avoid need for EBP. No prospective trials & low case numbers. A retrospective single-centre review of 81 pts, half had EBP & half had SPGB, none in the SPGB returned to ED for further Rx but 23% of the EBP returned. All pts were headache-free at 1 week.

Question 18

How do you perform transnasal sphenopalatine ganglion block?

Answer 18

Pt monitored (SpO2), positioned supine or semi-sitting, neck extended, inspect nares to ensure not trauma/obstruction, measure distance tip of nares to mandibular notch (depth of insertion), saturate cotton tip applicator with 2-5% lignocaine. Insert through each nostril, superior to the middle turbinate, parallel to zygoma with tip angled laterally until contacts posterior pharynx. Leave in place for at least 10 mins (up to 30 mins) then remove.

Question 19

What are the contraindications to SPGB?

Answer 19

allergy to any of the medications used, anticoagulation/coagulopathy, history of facial trauma (nares should be inspected for trauma or deviated septum), infection, and patient refusal

Question 20

What are complications of SPGB?

Answer 20

Minor adverse effects are typically local and include epistaxis, transient anesthesia, or hypoesthesia of the root of the nose, pharynx, and palate and lacrimation of ipsilateral eye. Major adverse effects are uncommon but can include infection in the setting of improper aseptic technique, local or retroorbital hematoma

Question 21

Is there an association between dural puncture and subdural haematoma?

Answer 21

yes, due to rupture of meningeal veins. there’s also an association with cerebral vein thrombosis and bacterial meningitis.

Question 22

What complication can occur with LOR to air?

Answer 22

pneumocephalus with a thunderclap headache- use symptomatic Rx

Question 23

What are the success & recurrence rates with EBP for Rx of PDPH?

Answer 23

95% have at least partial symptom relief- successful first EBP in 65-98%, similar success rates with subsequent patch. 30% have recurrent headache, 28% require subsequent EBP.

Question 24

Mechanism of success of EBP?

Answer 24

increase subarachnoid CSF pressure by compression from epidural space, then fibrin plug may seal the hole in dura & prevent further CSF leak