Our nerves are the messengers between our brains and the rest of our bodies. When they’re damaged, we lose some or all of the function of that body part. Minor nerve injuries can cause tingling, prickling, or partial numbness of the affected area. More serious injuries can cut off all feeling and function.
Babies are at risk for nerve injuries due to trauma during delivery or developmental defects.
Nerve Damage During Delivery
During delivery, your doctor may need to reposition the baby or pull on the baby to ease the passage through the birth canal. Unfortunately, that pulling and twisting can damage the baby’s nerves. The nerves most often damaged during delivery are the cranial nerve and the spinal cord.
The brachial plexus nerves are also at risk during delivery. For more information, check out the section on Brachial Plexus Injuries and Erb’s Palsy.
Cranial Nerve Injury
The cranial nerves connect your brain to your sensory organs. They allow you to see, hear, smell, and taste. They control the movement of your tongue and jaw. They allow you to make facial expressions and turn your head from side to side.
Pulling or twisting the baby’s neck during delivery may damage the cranial nerves. Improper placement of forceps or a vacuum during delivery can also damage these nerves. The symptoms of cranial nerve damage depend on which nerves are damaged, but the most common symptom is paralysis of part or all of one side of the face. The eye on the affected side may not be able to blink, requiring use of eyedrops and an eyepatch to protect the eye. In some very severe cases, the nerve that controls the diaphragm (the muscle that expands your lungs when you breathe) may be damaged, causing respiratory problems.
Cranial nerve injuries can also cause a variety of palsies, or muscle spasms and contractions. Bell’s palsy affects the face, causing one side of the face to droop. Palsies of the third, fourth, and sixth nerves affect the eyes, causing drooping and abnormal eye movement.
Most cranial nerve injuries acquired during delivery are mild. These minor injuries are called “neuropraxias” and occur when the nerves are stretched or compressed but not torn. Neuropraxias typically heal on their own within a week or two. If you don’t see improvement in the baby’s symptoms in that time, the injury may be a more serious tear or break. A tear or break in a nerve is called an “avulsion” or “rupture,” depending on the location of the injury. Surgery may help repair the damage in some cases, but others may be permanent and untreatable.
Spinal Cord Injury
Twisting and pulling on the baby during delivery doesn’t just risk the cranial nerves. It can also stretch or tear the spinal cord. The spinal cord is the large bunch of nerves that run down the middle of your spine. Damage to the spinal cord will affect the function of everything lower than the site of the injury.
Spinal cord injuries during delivery are rare – it takes a great deal of force to pull or twist hard enough to damage the spinal cord. When they do happen, they’re usually very serious. An injury to the spinal cord can affect your child’s ability to breathe and pump blood. If the injury is a mild neuropraxia, a life support machine can keep the baby alive long enough for the injury to heal. More serious injuries may be fatal.
Symptoms of Developmental Defects
The nervous system is one of the most complicated parts of the body and sometimes, things can go wrong during development in the womb. Fortunately, nervous system defects are rare. They fall into two main categories: neural tube defects and brain malformations.
Neural Tube Defect Symptoms
The neural tube is the structure that develops into the spinal cord and brain. It starts as a groove around one side of the embryo and then closes over into a complete tube as the embryo develops. Sometimes, the tube doesn’t completely close over. This is called “spina bifida.”
One common form of spina bifida is called “spina bifida occulta,” or “occult spinal dysraphism.” The vertebrae haven’t completely closed over the spinal cord but the opening is covered by skin. Babies with spina bifida occulta often have a dark, discolored, or hairy patch over the area of the spine that hasn’t completely closed. Otherwise, many have no symptoms at all. In more serious cases, the spinal cord may fuse to the skin above it. That can damage the spinal cord, affecting the child’s body below the site of the opening. Children with spina bifida occulta are also at increased risk for meningitis and damage to the part of the nerve not protected by the spinal cord.
A more severe type of spina bifida, “spina bifida cystica meningocele,” occurs when meninges, fluid, and other tissue bulges out through the hole in the spine. This causes a dark, fluid-filled lump on the baby’s spine. This form of spina bifida requires surgery to put the bulging tissues back in place and close up the spine. The meningocele may damage the spinal cord, affecting the functioning of the baby’s body below the site of the meningocele.
“Spina bifida cystica myelomeningocele” is the most dangerous form of spina bifida. It occurs when the spinal cord itself bulges out through the hole in the spine, along with the meninges and fluid. This typically causes severe damage to the spinal cord and most children with this condition will be severely impaired. Surgery is required to put the spinal cord back in place. Spina bifida cystica myelomeningocele is often accompanied by hydrocephaly, a condition in which excess fluid builds up and puts pressure on the baby’s brain.
Brain Malformation Symptoms
The symptoms of a brain malformation depend on the type of defect. Some brain malformations are fatal.
Many brain malformations are invisible from the outside. For example, “hydranencephaly” occurs when the cerebral hemispheres fail to form. Instead, sacs of cerebrospinal fluid take their place. The baby will look and act healthy for the first few weeks, but will then start to experience irritability and unusual growth in muscle mass. Within a few months, the baby will start to have seizures. Hydranencephaly is fatal for most children.
Porencephaly is a less severe form of the same malformation. Children with porencephaly have fluid-filled cysts in their cerebral hemispheres. Porencephaly may cause seizures and spasms, hydrocephaly, and cognitive disabilities.
Some brain malformations will show up on ultrasound, allowing diagnosis before delivery. Others may not be identified until after birth when seizures or developmental delays arise.