Types of Conjoined Twins

• Most Common Types:– Thoraco-omphalopagus – Thoracopagus – Omphalopagus – Parasitic – Craniopagus

• 75% of cases involve females

Thoraco-omphalopagus

• Account for 28% of cases• Fused together from the upper

chest to the lower chest• Typically share a heart;

sometimes share a liver or part of the digestive system

• Physiological complications include respiratory and circulatory problems

• The way the heart is fused determines the prognosis.

• Separation is usually out of the question because of the shared heart.

Thoracopagus

• 18.5% of cases• Fused at the upper thorax

to the lower belly• Heart is always involved• Separation usually

causes death to both twins because of their shared, and often weaken heart.

Omphalopagus

• 10% of cases• Conjoined from the

sternum to the groin• Often share a liver

and portions of digestive system

• Separation can be done and is usually successful.

Parasitic

• 10% of cases• Twins are asymmetrical• One twin is smaller and

dependent on the other for survival

• Some twins can live healthy lives and some can die soon after birth

• Parasitic types are: craniopagus, dipygus, and epigastric

Craniopagus• 6% of cases• Joined by a portion of the skull;

separate necks and bodies• Most are stillborn or die soon

after birth• Separation is risky because

the twins usually share parts of the brain and blood circulation

• Different types:– Frontal – forehead– Occipital- back of head– Parietal – side of head

• Physiological issues include seizures and brain anatomy asymmetry

Interesting Less Common Type

• Craniopagus Parasiticus– This type is a fusion of

craniopagus and parasitic in which they are conjoined at the cranium, but one twin has no body and totally relies on the other for survival.

Krista and Tatiana Hogan• Krista and Tatiana are two craniopagus

conjoined twins.• They are currently aged 4 and are living

relatively healthy lives in Canada.• One of the most intriguing aspects of

their lives is that they share reactions to certain feelings such as taste, pain, and sight. When one of them drinks something, the other will feel the satisfaction of drinking. If one of them is looking at a stuffed animal while the other isn’t, the other twin claims to see it as well.

• Douglas Cochrane, a neurosurgeon, accredits this phenomenon to the thalamic bridge that the two share. They both share a brainstem which connects their thalami; the thalamus deals with sensory output.

Krista and Tatiana Hogan (cont.)

• While most conjoined twins experience cardiac issues, they have been cleared as relatively healthy, although Tatiana’s heart has to work harder because it pumps blood to both bodies.

• Some health issues that Krista and Tatiana have encountered are seizures and they won’t be separated because of the risk of death and paralysis.

• Krista and Tatiana are also mentally slow by a couple of years due to their condition.

Health Concerns and Separation

• 40-60% of conjoined twins are stillborn, while many others die soon after birth. Overall survival rate = 25%

• Respiratory and Circulatory problems are most common because of shared hearts which deal with blood flow. When hearts are shared, they are typically much weaker than average hearts which makes involuntary bodily function much harder.

• Also, brain abnormalities such as seizures and corpus callosum dysgenesis can be present in craniopagus conjoined twins.

• The separation of conjoined twins usually depends on how the surgeon sees the twins living after the procedure. Often, the twins cannot be separated due to the way their organs are shared, especially the heart or other major organs. Separation is a very risky option because certain issues can occur after the procedure: blood clots can form in new blood vessels, heart complications, and lethal infections.

• Overall, the parents have to decide whether or not they want to risk losing their children if separation is an option.