The Hanefeld variant is an atypical form of Rett syndrome first described by Dr. Hanefeld in 1985. It is also called the early-onset seizure variant because patients usually experience epileptic seizures between the first week and the first five months of life. (The first seizures usually occur around age 2 in patients with classical Rett syndrome.)
Whereas classical Rett syndrome is caused by mutations in the MECP2 gene, the Hanefeld variant is caused by mutations in a gene called CDKL5. The protein product of the CDKL5 gene is abundant in nerve cells, and mutations in this gene hinder the normal development and function of these cells.
The most characteristic symptom of the Hanefeld variant of Rett syndrome is early-onset epileptic seizures. The seizures initially respond to anti-epileptic drugs but then return and do not respond to medication. These seizures are also called infantile spasms because they occur early in infancy. They are in the form of brief and infrequent attacks initially but then occur in clusters. Patients usually experience a sudden flexion and stiffening in the arms, legs, or whole body. Sometimes the episodes can be in the form of extensor spasms where the arms and legs are flung outwards. The seizures usually affect both sides of the body equally.
In classic Rett syndrome, patients usually experience tonic-clonic, myoclonic, tonic, or absence seizures.
Other symptoms of the Hanefeld variant of Rett syndrome include impaired psychomotor development, stereotypical hand movements that affect the ability to grasp, severely low muscle tone, autism-like features, and poor language skills. Some patients also have scoliosis, sensory issues, and gastrointestinal problems.
The head circumference is usually within the normal range both at birth and at the time of clinical examination in patients with this variant.
Medications for the Hanefeld variant of Rett syndrome treat the epileptic seizures.
The most commonly used anti-epileptic monotherapy or combination therapy are sodium valproate, carbamazepine, lamotrigine, levetiracetam, and topiramate. While sodium valproate, carbamazepine, and lamotrigine are mostly used as monotherapy, levetiracetam and topiramate are usually used as second-line treatments when the primary medications become inefficient, or as a part of a combined therapy with any of the first three medicines.
Vagus nerve stimulation is a newer therapy used to reduce the number and/or severity of seizures. The treatment requires minor surgery to implant a pacemaker-like device that sends impulses to the brain via the vagus nerve. A magnet then activates the device before or at the onset of seizure activity to help stop the seizure.
Recently, endoscopic corpus callosotomy (cutting through the corpus callostum to separate the two brain hemispheres so that seizures starting in one brain hemisphere do not extend to the other) has been used to eliminate seizures in an 8-year-old Rett syndrome patient with medically intractable epileptic drop attacks.
Aqua therapy, hippotherapy, and music therapy are commonly used in children with Rett syndrome to overcome behavioral, cognitive, language, and other neurological issues. These therapies give the best outcomes when they are used as soon as initial symptoms appear.
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