From the Guidelines
Chiari malformation type 1 is a condition that requires prompt diagnosis and management to prevent neurological damage, and patients with symptoms such as occipital or neck pain, peripheral motor and/or sensory defects, and respiratory irregularities should undergo cranial MRI or CT to detect cerebellar tonsils prolapse through the foramen magnum. The diagnosis of Chiari malformation type 1 is crucial, as it can cause compression of the lower brainstem and upper cervical cord, leading to symptoms and/or result in syringomyelia requiring surgical correction 1. Some key symptoms to look out for include:
- Occipital or neck pain exacerbated by Valsalva manoeuvres
- Peripheral motor and/or sensory defects
- Clumsiness
- Hyporeflexia or hyperreflexia
- Respiratory irregularities
- Central apnoeas
- Lower cranial nerve dysfunction It is essential to note that most cases of Chiari type 1 malformation are asymptomatic, but when symptoms occur, they can be debilitating and require prompt medical attention 1. In terms of management, surgical correction may be necessary to relieve pressure on the brain and spinal cord, improving cerebrospinal fluid flow 1. Given the potential for severe neurological damage, it is crucial to prioritize the diagnosis and management of Chiari malformation type 1, especially in patients with symptoms or those diagnosed with conditions such as X-linked hypophosphataemia, where the condition is detected in 25–50% of children by use of cranial MRI or CT 1.
From the Research
Definition and Classification of Chiari Malformation
- Chiari malformation is a group of anomalies characterized by the descent of the cerebellar tonsils or vermis into the cervical spinal canal 2.
- The malformation can be classified into different types, with Chiari malformation type 1 (CM-1) involving the cerebellar tonsils' descent below the foramen magnum, and Chiari malformation type 1.5 (CM-1.5) involving both the cerebellar tonsils and the brainstem herniation 3.
Symptoms and Associated Conditions
- Common symptoms of Chiari malformation include headaches and cervical pain, often associated with conditions like syringomyelia and hydrocephalus 3, 4.
- Other associated conditions include spina bifida, hydromyelia, curvature of the spine (kyphosis and scoliosis), and tethered cord syndrome 2.
Treatment Options
- Surgical treatment is not performed in asymptomatic patients, while the presence of syringomyelia represents an indication for surgery 3, 4.
- Posterior fossa decompression is the preferred treatment modality for Chiari malformation type 1 with syringomyelia, with most surgeons opening the dura 4.
- The choice between bony decompression alone and its combination with duraplasty is controversial in the pediatric population 3.
Factors Affecting Treatment Outcomes
- Factors such as age, sex, pretreatment symptoms, symptoms duration, and radiological findings can affect the outcomes of conservative and surgical treatment for Chiari malformation type 1 5.
- The presence of heavy sleep apnea or/and functional symptoms, tonsillar herniation >13.4 mm on coronal images, low aqueductal stroke volume (ASV), long symptom durations, and a syrinx are independent prognostic factors that can affect outcomes negatively 5.