Last update: 01/02/2019, Dr. Miguel B. Royo Salvador, Medical Board number 10389. Neurosurgeon y Neurologist.
The Arnold-Chiari Syndrome Type I consists in the herniation of the lower part of the brain – the cerebellar tonsils – and of the lower part of the cerebellum through the foramen magnum towards the spinal canal, without other associated spinal cord malformations. For some, the descent of the cerebellar tonsils must be greater than 5 mm, for others 3 mm, for some it can be 0 mm or the tonsils can be impacted with a compatible clinical picture.
Figure 1.- Diagram showing the tonsillar descent and the consequent increase in the supracerebellar space in the Arnold-Chiari syndrome, given that the entire cerebellum moves toward the spinal canal.
The clinical symptoms of the Arnold-Chiari Syndrome I (ACHSI) can be expressed in various sets of symptom combinations. Most frequent (from more to less recurrent) in our series are: headache, neck ache, paresis in extremities, visual alterations, pain in extremities, paraesthesia, sensitivity alterations, vertigo, swallowing alterations, lower back pain, memory alterations, gait alterations, upper back pain, altered balance, dysaesthesia, language disorder, sphincter alterations, insomnia, vomiting, fainting, tremors.
There are four classic types (I, II, III, IV) and two recently described ones (“0”, “1.5”):
Type I. Descended cerebellar tonsils with no other malformation of the Nervous System (NS).
Type II. Descended cerebellar tonsils with a neurospinal malformation that tethers the spinal cord to the spinal canal.
Type III. Descended cerebellar tonsils with occipital encephalocele and brain anomalies.
Type IV. Descended cerebellar tonsils with cerebellum aplasia or hypoplasia associated with tentorium aplasia.
Type “0”. At present, the existence of cases with signs and symptoms germane to the Arnold-Chiari Syndrome Type I, but without cerebellar tonsil descent, is being discussed.
Type “1.5”. The Arnold-Chiari Syndrome 1.5, with a descent of the cerebellar tonsils and brain stem herniation into the foramen magnum, has been described recently.
The descent of the cerebellar tonsils (DCT) can occur as a result of the traction that malformations associated with some forms of Arnold-Chiari syndrome exert on the spinal cord; except in Type I, where the descent of the cerebellar tonsils is the only morphological alteration – in this case, there are several theories-:
– Conventional theories:
The Cord Traction Theory according to the Filum System®:
Dr. Miguel B. Royo-Salvador’s theory considers the descent of the cerebellar tonsils in an Arnold-Chiari Syndrome Type I, as a result of abnormal traction of the spinal cord, due to an anomalous and excessively tense Filum Terminale ligament (not detectable on imaging).
Figure 2.- Magnetic Resonance (RM) images of a female patient at the age of 8 months (left) and 20 months (right). The emergence of a cerebellar tonsil descent from one image to the next can be observed. Huang P. “Acquired” Chiari I malformation. J. Neurosurg 1994. This indicates the existence of an acquired factor that besides the genetic and hereditary component.
The most influential risk factors for the development of the Arnold-Chiari Syndrome Type I are the following:
Complications of cerebellar tonsil ectopia may depend on the degree of caudal traction or the associated compression in the foramen magnum. The latter is determined by the conflict between the spinal cord traction, the brain stem and the space available in the foramen magnum.
The conventionally accepted treatment for Arnold Chiari I Syndrome is neurosurgical.
Currently, the craniectomy or suboccipital decompression is the standard treatment performed in most centers worldwide for this diagnosis, with or without syringomyelia. The indication is usually especially for severely symptomatic cases, as it causes more morbidity and mortality than the natural evolution of the condition itself.
Since 1993, however, with the publication of Dr Royo-Salvador’s doctoral thesis, which links the caudal traction of the entire nervous system due to the filum terminale to being the cause of cerebellar tonsil ectopia – among other diseases -, a new treatment has been designed. It is in this case etiological (cause-related) since the caudal cord traction force responsible for the pathological mechanism is eliminated by surgically sectioning the filum terminale.
Our technique for the sectioning of the Filum terminale (SFT) is minimally invasive and it usually indicated as soon as possible in all cases, from mildly to severely symptomatic, as its risks are minimal, much lower than those of the condition itself, and it also stops the condition’s progression.
More than 1500 Arnold-Chiari I patients, with or without idiopathic Syringomyelia and/or idiopathic Scoliosis, have already undergone surgery according to the Filum System® method.
The purpose of the surgical procedure is to stop the evolution of the disease and to prevent the ectopia and the injuries from increasing further. Nevertheless, in some cases remarkable improvements of the clinical status have been achieved, even including an ascent of the cerebellar tonsils.
Examples:
Described by: the anatomy surgeon John Cleland (1835-1925) from Perthshire, Scotland, in 1883. He described the elongation of the cerebellar vermis, the descent of the cerebellum and fourth ventricle in a child with hydrocephalus, encephalocele, spina bifida and myeloschisis. In 1891 and 1896 Hans Chiari contributed new cases and their classification. In 1894 Julius Arnold contributed by spreading the information.
Named by: Schwalbe and Gredig, in 1907, as “malformation of Arnold-Chiari”. The current terminology is “Arnold-Chiari Syndrome” (ACHS) International Statistical Classification of Diseases and Related Health Problems, 10th Revision (c) Geneva, WHO, 1992. (Q07.0, ICD-10).
Incidence: One case per one thousand live births, other authors point out just under one per cent of the population. In both cases the numbers are bound to very restrictive current criteria, with a descent of the cerebellar tonsils of more than 3 or 5 mm.
Dr. Royo-Salvador, with his research and doctoral thesis (1992), proved the theory that considers several diseases of unknown cause (Arnold-Chiari Syndrome Type I, idiopathic Syringomyelia, idiopathic Scoliosis, platybasia, basilar invagination, odontoid retroflexion, brain stem kinking, and others) as part of a new disease concept (the Filum Disease) and that they share a common cause (spinal cord and entire nervous system traction).
The traction force of the entire nervous system in the Filum Disease occurs in all human embryos, hence they all suffer its consequences to a greater or lesser extent, and the consequences manifest in many different ways and intensities.
Other diseases, such as herniated discs, some cerebral vascular insufficiency syndromes, facet joint and Baastrup syndromes, fibromyalgia, chronic fatigue, nocturnal enuresis, urinary incontinence and pronounced paraparesis, are related, due to their cause, to the Filum Disease.
A health method, the Filum System®, has been designed to specify the diagnosis, provide guidance for the treatment and follow-up of: the Filum System®.
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