Case 2: Coma in an apparently well toddler

A two-year-old boy presented to the emergency department in the early morning with a coma. The child had mild symptoms of low-grade fever for two days and had no bowel movement for 24 h before admission.

His medical history was unremarkable. Specifically, there were no known congenital anomalies and no previous surgeries.

The child was moribund, with a body temperature of 33.6°C per axilla, a blood pressure of 63/25 mmHg, a respiratory rate of 14 breaths/min and a heart rate of 94 beats/min. The capillary refill time was 4 s. The modified Glasgow coma scale score was 3/15. His pupils were equal and reactive. A clinical examination did not indicate an underlying diagnosis.

In his obtunded state, he received bag and mask ventilation before intubation and ventilation. He was admitted to the intensive care unit, and given resuscitative fluids and inotropic support. Broad-spectrum antibiotics and antiviral therapy were commenced.

Core investigations were performed using the evidence-based prescriptive algorithm for the approach to the child with decreased conscious level, as suggested by Bowker et al (1), and based on the guideline devised by the United Kingdom Paediatric Accident and Emergency Research Group (2).

His hemoglobin level was 90 g/L (normal 105 g/L to 127 g/L), with a white blood cell count of 26.2×10⁹/L (normal 6×10⁹/L to 15×10⁹/L; neutrophils 10×10⁹/L) and a prolonged activated partial thromboplastin time of 63 s (normal 42 s to 54 s). Metabolic dysfunction was evidenced by venous gas sampling (pH 6.521 [normal 7.35 to 7.45]; PCO₂ 12.5 kPa [normal 4.5 kPa to 6 kPa]; PO₂ 2.5 kPa [normal 3 kPa to 5.3 kPa]; HCO₃⁻ 3.5 mmol/L [normal 18 mmol/L to 25 mmol/L]; base excess −34.4 mmol/L [normal −3 mmol/L to +4 mmol/L]); and a plasma lactate level of 9 mmol/L (normal 0.5 mmol/L to 2.2 mmol/L). Renal and hepatic dysfunction was evident (urea 12.6 mmol/L [normal 3.3 mmol/L to 6.5 mmol/L]; creatinine 360 μmol/L [normal 25 μmol/L to 60 μmol/L]; potassium 6.0 mmol/L [normal 3.5 mmol/L to 5 mmol/L]; sodium 143 mmol/L [normal 135 mmol/L to 145 mmol/L]; calcium 2.14 mmol/L [normal 2.25 mmol/L to 2.6 mmol/L]; alanine aminotransferase 766 U/L [normal <45 U/L]; aspartate aminotransferase 2006 U/L [normal 15 U/L to 55 U/L]; gamma-glutamyl transpeptidase 63 U/L [normal <30 U/L]; and plasma ammonia 128 μmol/L [normal 0 μmol/L to 100 μmol/L]). The laboratory blood glucose was 22 mmol/L (normal fasting glucose <6.1 mmol/L), without ketonuria. Blood and urine toxicology screens were negative. Blood culture was negative. Plasma, serum and urine, subsequently analyzed, ruled out any inborn error of metabolism. A chest x-ray was normal. An abdominal x-ray in the supine position showed no features of obstruction or perforation. An abdominal ultrasound, focusing on the liver, spleen and kidneys, was normal. Computed tomography of the brain demonstrated marked cerebral edema.

Despite maximal therapeutic support, the child died after 24 h. The diagnosis became evident on postmortem examination.

CASE 2 DIAGNOSIS: LARGE BOWEL VOLVULUS PRESENTING WITH COMA AND SHOCK

A diagnosis of large bowel volvulus with ischemia and necrosis of the right and transverse colon was made at postmortem examination.

In the United Kingdom paediatric population, the incidence of nontraumatic coma is 30.8/100,000 per year, with the majority of patients being younger than one year of age at presentation (3). Recognizing that in 14% of cases, no clear etiology is determined, and given the attendant mortality and morbidity associated with coma, evaluation must be prompt and effective (3). The progression of coma is dynamic and the sequencing of investigation must be methodical to uncover the underlying etiology.

Intestinal pathology, while rare, is recognized as a cause of coma. No mechanism clearly explains the pathophysiology of coma in these children. While speculative, pain is probably a factor because once there is resolution of intussusception, the coma remits (4). Prescriptive algorithms provide a comprehensive approach to the child presenting with impaired conscious level (1,2). However, there is no focus on the rarer causes including intussusception and volvulus.

The mnemonic ‘AEIOU TIPS’ provides a memory aid for the doctor to address the multiplicity of etiologies of coma (Table 1). Where intussusception has been suggested as an additional ‘I’ in the mnemonic (5), it refers to cases of intussusception for which presentation characterized by altered sensorium is described, but the diagnosis has been suggested by the progression of symptoms, especially the development of bloody stools.

TABLE 1.

Mnemonic: AEIOU TIPS

A	Alcohol
E	Endocrine, Electrolytes, Encephalopathy
I	Insulin (hypoglycemia), Inborn errors of metabolism, Intussusception
O	Opiates, Oxygen (hypoxia)
U	Uremia
T	Trauma, Toxidromes, Temperature
I	Infections (sepsis/meningitis)
P	Psychogenic
S	Space occupying lesion, Seizure, Shock, Stroke

Volvulus in the paediatric population is rare. In a published case series of seven developmentally delayed patients, seen over a six-year period, nearly all had abdominal tenderness, distension, constipation and bloody mucoid discharge (6). The mechanism of coma remains elusive, but it is reasonable to propose that it is the result of ischemia in this closed-loop obstruction causing sepsis and shock, while pain may also be a factor.

We suggest that the additional ‘I’ in the mnemonic AEIOU TIPS should stand for ‘intestinal pathology’ to incorporate not only intussusception, but also the rare cases of volvulus. For our patient, a plain film x-ray of the abdomen was obtained and an abdominal ultrasound was performed. While a gasless air pattern on abdominal x-ray would have been clinically helpful, the child required bag and mask ventilation during resuscitation, presumably causing inadvertent gas insufflation, thereby reducing the usefulness of x-ray imaging.

Given the evidence of major organ dysfunction and metabolic acidosis in the present case, ultrasound imaging reports focused on the solid organs in the abdomen rather than on findings specific to the presence of intestinal pathology (specifically, orientation of the superior mesenteric artery to the vein), which may have indicated the presence of malrotation and volvulus, and were not commented on.

When a child is in a coma for which the paediatrician has reached the ‘cause unknown’ portion of the algorithm, consideration must be given to intra-abdominal etiologies, especially volvulus, because it is a surgical emergency. Requesting abdominal imaging could be life saving, but the radiologist must be informed of the potential pathologies being considered, especially if the radiologist’s predominant area of expertise is adult radiology. We suggest that the paediatrician prompt the radiologist to look at the orientation of the superior mesenteric artery to the vein on abdominal ultrasound; thereby, possibly providing a clue as to the presence of malrotation. Computed tomography is an optimal imaging technique to depict the ‘whirl’ or ‘whirlpool’ sign, defined as a whirl-like pattern produced by central vessels partly, or entirely encircled by bowel loops (Figure 1). The whirl sign is usually associated with mid-gut, cecal and sigmoid volvulus.

Figure 1).

Computed tomography showing the whirl sign

CLINICAL PEARLS

• Fourteen per cent of cases of nontraumatic coma have no clear etiology. The etiologies of nontraumatic coma are often remembered by the mnemonic AEIOU TIPS, in which ‘I’ may variously refer to insulin, infection, inborn errors of metabolism and intussusception (5). This should now be expanded to include an additional ‘I’, referring to intestinal pathology inclusive of intussusception and volvulus.

• Volvulus, when presenting as a coma, is likely to result in death if it is not recognized.

• Focused abdominal imaging is likely to be helpful if the radiologist is informed of the potential etiologies and is, thereby, prompted to look at the orientation of the superior mesenteric artery to the vein on ultrasound, and the presence of the whirl sign on computed tomography. Once recognized, the volvulus must be corrected surgically.