Treating postdural puncture headache in COVID-19 positive patient- is bilateral greater occipital nerve block the answer?

To the Editor,

Postdural puncture headache (PDPH) is an undesirable complication experienced after a spinal anesthetic, after an inadvertent dural puncture during epidural space identification, after diagnostic lumbar punctures, and after intrathecal injections of chemotherapeutic agents in cancer patients. A parturient could develop PDPH after lower segment cesarean section (LSCS) under spinal anesthesia or normal vaginal delivery after epidural analgesia during which there is inadvertent dural puncture. An epidural blood patch (EBP) is considered gold standard when conservative measures fail and has a success rate of up to 75%.[1]

Bauer et al. described the management of COVID-19 positive obstetric patients due to severe acute respiratory syndrome coronavirus 2 (SARSCoV-2).[2] The review deals with evidence-based recommendations and expert opinion when evidence is scarce. The paper has not described best practice for managing PDPH in obstetric patients possibly due to scarcity of literature or no report as of now. Till date there is no paper describing the management of PDPH experienced postoperatively in COVID-19 positive patients.

In COVID-19 patients, the sequelae to viral shedding from the autologous blood injected in the epidural space after an EBP is not known. Central nervous system involvement has been described as a possibility due to presenting as acute cerebrovascular diseases, loss of consciousness, and skeletal weakness.[3] Based on available data, the incidence of thrombocytopenia in COVID-19 positive patients is around 36% and the percentage increases based on the severity of the disease.[4] Thus, viral shedding in epidural space leading to possible neurological issues and underlying thrombocytopenia are two limiting factors in offering EBP to patients. Till date data of qualitative function of platelets in thrombocytopenic COVID-19 patients has not been described or explored.

Bilateral trans-nasal sphenopalatine ganglion block (SPGB) is a minimally invasive, office-based procedure, which has been quite effective in managing PDPH. The procedure is safe, can be repeated, and has no serious adverse effects per se.[5] However, in a COVID-19 positive patient, there could be coughing or sneezing while performing the block, which could lead to aerosol generation in the premises, which is not desirable.

Bilateral greater occipital nerve block (GONB) is another intervention described, which has been successfully used to treat headache due to various etiologies including PDPH.[6] Bilateral GONB can be performed using landmark technique, with neurostimulation or with ultrasound (US) guidance with patient in prone or sitting position with neck flexed. With landmark technique, the greater occipital protuberance (GOP) is identified and a line is drawn 3–3.5 cm downwards. From that point, 2–2.5 cm laterally the injection is made medial to the pulsation of greater occipital artery (GOA). With neurostimulation using 0.3 mA, injection is made at above mentioned landmark at the point where patient appreciates a tingling sensation. With US using a high frequency linear array probe (8–13 MHz), the injection is made after identifying the pulsations of GOA medial to it with the probe places transversely at 3–3.5 cm caudal to GOP and injections performed bilaterally using 2 ml of local anesthetic on each side. After a bilateral GONB there is “winding down” of central sensitization due to interruption of afferent input to the dorsal horn and trigeminal nucleus caudalis (TNC) neurons temporarily, which relieves theheadache. Transientdizziness, alopecia, and hematoma at the site of injection are the adverse events reported but were never serious.

In the current scenario with human-to-human transmission of SARSCoV-2 is very high due to aerosol, and safety of EBP is not established due to viral shedding, bilateral GONB appears the safest intervention to deal with patients suffering with PDPH even after conservative management in the form of hydration, acetaminophen, gabapentinoids, and caffeine. To conclude, patients with PDPH could be offered bilateral GONB as it is easy to perform, safe, and can be repeated if required.

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