Common #POCUS cases in Laos rarely in developed areas. What is the etiology? #FOAMed #meded

 

Another trip where POCUS makes a massive impact for the local population.  In Laos Luang Prabang is the location of a (relatively) new children’s hospital.  Founded and funded by Friends Without Borders in conjunction with the Lao ministry of health.  Here Lao physicians, nurses and support staff are being trained to care for a population who is in great need.  Many children who suffer from malnutrition, die from dehydration and gastroenteritis, and whole host of treatable conditions.  Barriers to diagnostic imaging is one part of the long list of needed things in low resource environments.  Here there is portable x-ray and ultrasound.  Computed tomography is available at a price that most cannot afford and located at separate hospital in another part of the city.  Therefore, you inevitably ultrasound injuries and illnesses you typically would not in a high resource emergency department.  In additional to the lungs of the patient with shortness of breath, the soft tissue of the infected patient, bones of the injured patient we placed the probe on neck masses, hip joints, countless scrotums, and fontanelles (but not in that order).  As usual we encountered many interesting cases, which I will share for educational purposes.  Let us start with an extremely common disease seen in Laos that is extremely rare in high resource countries.

A 7-year-old boy presents for an inability to bear weight on the right leg.  He was fishing with a bow and arrow 14 days ago.  He fired an arrow, which hit a rock and bounced backwards penetrating his right knee.  The arrow was removed by the patient’s father and he seemed fine.  He gradually developed leg pain and refusal to bend his knee.  The terribly pain he felt however, localized to his posterior right thigh and calf, not the knee.

He presents to the hospital with a fever, refuses to walk or range his right knee.  On exam, the knee appears relatively normal.  There is a single, well healed puncture wound on the medial aspect, but the knee is non-painful to palpation, there is no effusion, no warmth, no redness.  However, when you attempt to passively range the knee the child screams in pain.  When the posterior right thigh is palpated there is large painful mass.  There is no fluctuance, the mass feels deep, and there is no redness, no warmth or other skin changes.  There is a similar mass in the posterior right calf, also feels deep without any skin changes.

Labs are sent which show elevated ESR and white blood cell counts

A POCUS is done starting first at the distal posterior thigh on non-painful, normal appearing tissue.

 

The POCUS was continued by continuous transverse imaging, moving towards the proximal posterior thigh.

An area within the posterior thigh muscles that was clearly hypoechoic compared to the unaffected leg appeared in view.  The superficial soft tissue appeared to be largely unaffected.

The muscle became increasingly hypoechoic as we scanned proximal in the thigh.  The affected muscle was larger in size compared to the unaffected leg and a discrete anechoic region was found with irregular borders.

A similar hypoechoic, enlarged region was identified in the right posterior calf with a very small discrete anechoic area.

Images of the knee were taken as well that demonstrated no significant joint effusion.

The diagnosis is pyomyositis of the posterior thigh and calf with early abscess formation.

Pyomyositis is a rare occurrence in high resource settings, but seen daily in a clinical setting like Laos.  Patient’s present with progressive muscle pain, swelling, pain with movement of the affected muscle and typically fever.  Most commonly the infection is caused by gram positive staphococcus.  The staph infections in Northern Laos typically respond to Cefazolin and therefore penicillin resistance is thought to be low.  In Laos (and many other countries) parents will seek help for their child’s fever at local pharmacies where pharmacists can provide intra-muscular (IM) injections of antibiotics, anti-pyretics, and pain medication.  I suspect that some of the pyomyositis is caused by improperly given IM injections by parents who were not provided proper education.  However, it is clear that this does not explain the volume of cases putting children in the hospital and the underlying etiology remains a mystery.

This patient recovered after two weeks of intra-venous antibiotics (Cefazolin).  He was discharged with a slight limp and asked to return to the outpatient clinic for a re-check in one week.  Other cases with larger fluid collections required incision and drainage.

Huge thanks to Friends without Borders, Lao Friends Hospital for Children and Sonosite.