Cranial epidural abscess

Inspired by Priola et al 2019.[1]

This is the first reported case of a cranial epidural abscess as a likely complication of acupuncture treatment. The report was written by the specialist neurosurgical team under whom the patient was admitted. This is often the case in such unusual and serious adverse events, but it also limits the details available about the acupuncture treatment – those details most relevant to acupuncture practitioners.

The patient was taking azathioprine 50mg per day for her Crohn’s disease. This is an immunosuppressant (cytotoxic) drug, but it is not clear to what degree this 47 year old woman was actually immunocompromised by this dose. The report does not include her body weight, which we need to estimate the relative dose (normally 2-2.5 mg/kg for maintenance of remission of Crohn’s disease). It seems likely that the dose was on the low side for an adult woman. Also we have no details of her white cell count prior to admission, although this certainly would have been measured from time to time to monitor the impact of the drug on her bone marrow.

Azathioprine for Crohn’s disease may have caused significant immunosuppression

We are told that she received acupuncture for left sided “occipital neuralgia” with needling to the left side of the neck from one month prior to admission. The acupuncture successfully treated her “neck pain”, but she developed a new and different headache. The narrative leads us to believe that a collection developed at the site of needling, although this is clearly not in the neck. I am not trying to make an argument that acupuncture may not have been the cause of infection in this case, but just illustrating the frustrating lack of detail for practitioners.

The infection developed under the aponeurosis of the scalp, the so called galea aponeurotica. Inoculation to this level with an acupuncture needle is certainly possible, since the depth from the skin surface is generally less than a centimetre, and we know inoculation to 7.5-12.5mm is possible from a prior report.[2] Deeper infections have occurred but not via direct inoculation.

I guess the most interesting and alarming thing about this case is the intracranial spread of the infection. The authors suggest this is likely to be via a calvarian foramina or diploic vein. The most common connections from outside to inside the skull are emissary veins. In this case there was no visible route, and no sign of osteomyelitis – frank infection in the bone. But the overlap of the abscesses is highly suggestive of direct spread.

T1-weighted axial MRI image showing an epidural and extracranial fluid collection, centered upon the left occipital region – from Priola et al 2019.[1]

The bug was a commensal Strep – Streptococcus anginosus. It may well have been sitting on the skin of the scalp where a needle penetrated the aponeurosis.

Streptococcus anginosus

The paper includes a fairly thorough review of past reports including CNS infections related to acupuncture (21). Most of these are of spinal abscesses, still serious conditions, but not quite as alarming as this the intracranial variety.

Will this change my practice of acupuncture? I guess not by much, but it does raise a relative reluctance to needle the scalp if it is not absolutely necessary. This could be seen as a problem if you are a follower of the famed Yamomoto – the architect of YNSA. How and why he came up with a the idea of a somatotopic map on the scalp is a story for another day…

References

1         Priola SM, Moghaddamjou A, Ku JC, et al. Acupuncture induced cranial epidural abscess: Case report and review of the literature. World Neurosurg Published Online First: 8 February 2019. doi:10.1016/j.wneu.2019.01.189

2         Woo PC, Li JH, Tang W, et al. Acupuncture mycobacteriosis. N Engl J Med 2001;345:842–3. doi:10.1056/NEJM200109133451119


Declaration of interests MC