Symptoms and Associated Health Conditions

While the brain malformation in Lobar Holoprosencephaly (HPE) is permanent, many of the symptoms and associated conditions it causes are manageable. Because Lobar HPE is the mildest form, the symptoms may be less obvious than in more severe types, but regular monitoring is essential to ensure your child receives the right support as they grow.

Neurological Manifestations

The brain’s structure directly influences how it sends and receives signals. In Lobar HPE, the areas where the brain remains fused can lead to several neurological challenges:

• Developmental Delays: Most children with Lobar HPE will experience some degree of developmental delay ^[1]. This can affect motor skills (like sitting or walking), speech, and cognitive learning. The degree of delay varies widely, and early intervention therapies are often recommended ^[2][3].
• Seizures and Epilepsy: The brain’s fusion can disrupt electrical activity, leading to seizures ^[1]. These may range from subtle “staring spells” to more noticeable physical movements. Most seizures in children with HPE can be managed with medication ^[1][4]. Work with your neurologist to create an emergency seizure action plan so you know exactly what to do if one happens at home.
• Hydrocephalus: This is a buildup of cerebrospinal fluid in the brain’s chambers. Because the fluid cannot always drain properly, it can cause increased pressure. Some children may require a shunt—a small tube surgically placed to drain the excess fluid into the abdomen ^[5].

The “Invisible” Challenge: Endocrine Issues

The area of the brain most often affected by HPE is near the hypothalamus and pituitary gland, which act as the body’s “control center” for hormones ^[6]. These issues are often called “invisible” because you cannot see them on the outside.

• Central Diabetes Insipidus (DI): This is one of the most common and critical endocrine issues in HPE ^[7]. It occurs when the body does not produce enough vasopressin, the hormone that tells the kidneys to save water. Without it, a child may lose too much fluid.
  Safety Warning: DI is a potential medical emergency, especially in infants. Because babies cannot fetch their own water or express thirst, DI can rapidly lead to life-threatening dehydration and dangerous blood sodium levels (hypernatremia). Strict fluid management is essential, and parents must have a clear “sick day” plan with their endocrinologist for handling common illnesses (like vomiting or diarrhea) ^[7][8].
• Pituitary Dysfunction: The pituitary gland may not produce enough growth hormone, thyroid-stimulating hormone, or cortisol. This can lead to slow growth, low energy, or problems managing stress ^[9][10]. Regular screening by a pediatric endocrinologist is vital for all children with HPE ^[6].

Facial and Physical Features

In Lobar HPE, facial features are often very subtle or even “typical.” However, certain midline features can be common clues for doctors ^[11]:

• Hypotelorism: This is the medical term for eyes that are closer together than usual ^[11][12].
• Solitary Median Maxillary Central Incisor (SMMCI): Some children are born with only one large front tooth exactly in the middle of their mouth instead of two ^[13][14].
• Nasal Findings: A child may have a very narrow nasal bridge or narrow nasal passages ^[11].
• Midface Hypoplasia: The middle part of the face (cheeks and nose) may appear slightly flatter or less developed ^[12][15].

(Note: Severe facial anomalies, such as a median cleft lip, are exceedingly rare in Lobar HPE and are much more commonly associated with the severe Alobar form ^[12].)

A Multidisciplinary Approach

Because Lobar HPE affects multiple systems in the body, your child will likely need a “team” of doctors ^[6]. This team usually includes a neurologist for the brain and seizures, an endocrinologist for hormone balance, and developmental specialists to help with milestones. Coordination between these specialists is the best way to manage these conditions and improve your child’s quality of life ^[16][17].