Hydranencephaly

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Hydranencephaly
Hydrancephaly
Hydranencephaly.jpg
Light passing through the skull of a hydranencephalic baby, underscoring the absence of the forebrain
— Image courtesy of D. P. Agamanolis
Specialty Medical genetics   OOjs UI icon edit-ltr-progressive.svg

Hydranencephaly [1] is a condition in which the brain's cerebral hemispheres are absent to a great degree and the remaining cranial cavity is filled with cerebrospinal fluid. [2] "Cephalic" is the scientific term for "head" or "head end of body".

Contents

Hydranencephaly [3] is a type of cephalic disorder. These disorders are congenital conditions that derive from damage to, or abnormal development of, the fetal nervous system in the earliest stages of development in utero. These conditions do not have any definitive identifiable cause factor. Instead, they are generally attributed to a variety of hereditary or genetic conditions, but also by environmental factors such as maternal infection, pharmaceutical intake, or even exposure to high levels of radiation. [4]

Hydranencephaly should not be confused with hydrocephalus, which is an accumulation of excess cerebrospinal fluid in the ventricles of the brain.

In hemihydranencephaly, only half of the cranial cavity is affected. [5]

Signs and symptoms

An infant with hydranencephaly may appear normal at birth or may have some distortion of the skull and upper facial features due to fluid pressure inside the skull. The infant's head size and spontaneous reflexes such as sucking, swallowing, crying, and moving the arms and legs may all seem normal, depending on the severity of the condition. However, after a few weeks the infant sometimes becomes irritable and has increased muscle tone (hypertonia). After several months of life, seizures and hydrocephalus may develop, if they did not exist at birth. Other symptoms may include visual impairment, lack of growth, deafness, blindness, spastic quadriparesis (paralysis), and intellectual deficits.[ citation needed ]

Some infants may have additional abnormalities at birth including seizures, myoclonus (involuntary sudden, rapid jerks), limited thermoregulation abilities, and respiratory problems. Still other infants display no obvious symptoms at birth, going many months without a confirmed diagnosis of hydranencephaly. In some cases severe hydrocephalus, or another cephalic condition, is misdiagnosed.[ citation needed ]

Causes

Hydranencephaly is an extreme form of porencephaly, which is characterized by a cyst or cavity in the cerebral hemispheres.[ citation needed ]

Although the exact cause of hydranencephaly remains undetermined in most cases, the most likely general cause is by vascular insult, such as stroke, injury, intrauterine infections, or traumatic disorders after the first trimester of pregnancy. In a number of cases where intrauterine infection was determined to be the causing factor, most involved toxoplasmosis and viral infections such as enterovirus, adenovirus, parvovirus, cytomegalovirus, herpes simplex, Epstein-Barr, and syncytial viruses. Another cause factor is monochorionic twin pregnancies, involving the death of one twin in the second trimester, which in turn causes vascular exchange to the living twin through placental circulation through twin-to-twin transfusion, causing hydranencephaly in the surviving fetus. [6] One medical journal reports hydranencephaly as an autosomal inherited disorder with an unknown mode of transmission, causing a blockage of the carotid artery where it enters the cranium; this causes obstruction and damage to the cerebral cortex. [3]

Genetic

Hydranencephaly is a recessive genetic condition, so both parents must carry the asymptomatic gene and pass it along to their child. There is a 25% chance that both parents will pass the gene to their child, resulting in hydranencephaly. Genetic hydranencephaly afflicts both males and females in equal numbers.[ citation needed ]

Post-natal brain injury

Though hydranencephaly is typically a congenital disorder, it can occur as a postnatal diagnosis in the aftermath of meningitis, intracerebral infarction, ischemia, or a traumatic brain injury. [7]

Diagnosis

An accurate, confirmed diagnosis is generally impossible until after birth, though prenatal diagnosis using fetal ultrasonography (ultrasound) can identify characteristic physical abnormalities. After birth, diagnosis may be delayed for several months because the infant's early behavior appears to be relatively normal. The most accurate diagnostic techniques are thorough clinical evaluation (considering physical findings and a detailed patient history); advanced imaging techniques, such as angiography, computerized tomography (CT scan), and magnetic resonance imaging (MRI); and (more rarely) transillumination. [3] However, diagnostic literature fails to provide a clear distinction between severe obstructive hydrocephalus and hydranencephaly, leaving some children with an unsettled diagnosis. [7]

Preliminary diagnosis may be made in utero via standard ultrasound, and can be confirmed with a standard anatomy ultrasound. Hydranencephaly is sometimes misdiagnosed as bilaterally symmetric schizencephaly (a less destructive developmental process on the brain), severe hydrocephalus (cerebrospinal fluid excess within the skull), or alobar holoprosencephaly (a neurological developmental anomaly).

Once destruction of the brain is complete, the cerebellum, midbrain, thalami, basal ganglia, choroid plexus, and portions of the occipital lobes typically remain preserved to varying degrees. The cerebral cortex is absent; however, in most cases, the fetal head remains enlarged due to increased intracranial pressure, which results from inadequate reabsorption of the cerebrospinal fluid produced in the choroid plexus. [6]

Prognosis

There is no standard treatment for hydranencephaly. Treatment is symptomatic and supportive. An accompanying diagnosis of hydrocephalus may be treated with surgical insertion of a shunt; this often improves prognosis and quality of life. [8]

The prognosis for children with hydranencephaly is generally quite poor. Death often occurs within the first year of life, [9] though many children live several years, or even into adulthood; in one reported case, a woman with hydranencephaly was assessed at age 32. [10]

Occurrence

This condition affects under 1 in 10,000 births worldwide. [6] Hydranencephaly is a rare disorder in the United States, which is defined as affecting fewer than 1 in 250,000. [11]

See also

Related Research Articles

<span class="mw-page-title-main">Cerebrospinal fluid</span> Clear, colorless bodily fluid found in the brain and spinal cord

Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates.

<span class="mw-page-title-main">Syringomyelia</span> Disorder in which a cyst forms in the spinal cord

Syringomyelia is a generic term referring to a disorder in which a cyst or cavity forms within the spinal cord. Often, syringomyelia is used as a generic term before an etiology is determined. This cyst, called a syrinx, can expand and elongate over time, destroying the spinal cord. The damage may result in loss of feeling, paralysis, weakness, and stiffness in the back, shoulders, and extremities. Syringomyelia may also cause a loss of the ability to feel extremes of hot or cold, especially in the hands. It may also lead to a cape-like bilateral loss of pain and temperature sensation along the upper chest and arms. The combination of symptoms varies from one patient to another depending on the location of the syrinx within the spinal cord, as well as its extent.

<span class="mw-page-title-main">Hydrocephalus</span> Abnormal increase in cerebrospinal fluid in the ventricles of the brain

Hydrocephalus is a condition in which an accumulation of cerebrospinal fluid (CSF) occurs within the brain. This typically causes increased pressure inside the skull. Older people may have headaches, double vision, poor balance, urinary incontinence, personality changes, or mental impairment. In babies, it may be seen as a rapid increase in head size. Other symptoms may include vomiting, sleepiness, seizures, and downward pointing of the eyes.

<span class="mw-page-title-main">Spina bifida</span> Birth defect of the spinal cord

Spina bifida /ˌspaɪnə ˈbɪfɪdə/ is a birth defect in which there is incomplete closing of the spine and the membranes around the spinal cord during early development in pregnancy. There are three main types: spina bifida occulta, meningocele and myelomeningocele. Meningocele and myelomeningocele may be grouped as spina bifida cystica. The most common location is the lower back, but in rare cases it may be in the middle back or neck.

Cephalic disorders are congenital conditions that stem from damage to, or abnormal development of, the budding nervous system.

<span class="mw-page-title-main">Colpocephaly</span> Medical condition

Colpocephaly is a cephalic disorder involving the disproportionate enlargement of the occipital horns of the lateral ventricles and is usually diagnosed early after birth due to seizures. It is a nonspecific finding and is associated with multiple neurological syndromes, including agenesis of the corpus callosum, Chiari malformation, lissencephaly, and microcephaly. Although the exact cause of colpocephaly is not known yet, it is commonly believed to occur as a result of neuronal migration disorders during early brain development, intrauterine disturbances, perinatal injuries, and other central nervous system disorders. Individuals with colpocephaly have various degrees of motor disabilities, visual defects, spasticity, and moderate to severe intellectual disability. No specific treatment for colpocephaly exists, but patients may undergo certain treatments to improve their motor function or intellectual disability.

<span class="mw-page-title-main">Holoprosencephaly</span> Medical condition

Holoprosencephaly (HPE) is a cephalic disorder in which the prosencephalon fails to develop into two hemispheres, typically occurring between the 18th and 28th day of gestation. Normally, the forebrain is formed and the face begins to develop in the fifth and sixth weeks of human pregnancy. The condition also occurs in other species.

<span class="mw-page-title-main">Lissencephaly</span> Medical condition

Lissencephaly is a set of rare brain disorders whereby the whole or parts of the surface of the brain appear smooth. It is caused by defective neuronal migration during the 12th to 24th weeks of gestation resulting in a lack of development of brain folds (gyri) and grooves (sulci). It is a form of cephalic disorder. Terms such as agyria and pachygyria are used to describe the appearance of the surface of the brain.

Porencephaly is an extremely rare cephalic disorder involving encephalomalacia. It is a neurological disorder of the central nervous system characterized by cysts or cavities within the cerebral hemisphere. Porencephaly was termed by Heschl in 1859 to describe a cavity in the human brain. Derived from Greek roots, the word porencephaly means 'holes in the brain'. The cysts and cavities are more likely to be the result of destructive (encephaloclastic) cause, but can also be from abnormal development (malformative), direct damage, inflammation, or hemorrhage. The cysts and cavities cause a wide range of physiological, physical, and neurological symptoms. Depending on the patient, this disorder may cause only minor neurological problems, without any disruption of intelligence, while others may be severely disabled or die before the second decade of their lives. However, this disorder is far more common within infants, and porencephaly can occur both before or after birth.

<span class="mw-page-title-main">Schizencephaly</span> Medical condition

Schizencephaly is a rare birth defect characterized by abnormal clefts lined with grey matter that form the ependyma of the cerebral ventricles to the pia mater. These clefts can occur bilaterally or unilaterally. Common clinical features of this malformation include epilepsy, motor deficits, and psychomotor retardation.

<span class="mw-page-title-main">Ventricular system</span> Set of structures containing cerebrospinal fluid in the brain

In neuroanatomy, the ventricular system is a set of four interconnected cavities known as cerebral ventricles in the brain. Within each ventricle is a region of choroid plexus which produces the circulating cerebrospinal fluid (CSF). The ventricular system is continuous with the central canal of the spinal cord from the fourth ventricle, allowing for the flow of CSF to circulate.

<span class="mw-page-title-main">Lumbar puncture</span> Procedure to collect cerebrospinal fluid

Lumbar puncture (LP), also known as a spinal tap, is a medical procedure in which a needle is inserted into the spinal canal, most commonly to collect cerebrospinal fluid (CSF) for diagnostic testing. The main reason for a lumbar puncture is to help diagnose diseases of the central nervous system, including the brain and spine. Examples of these conditions include meningitis and subarachnoid hemorrhage. It may also be used therapeutically in some conditions. Increased intracranial pressure is a contraindication, due to risk of brain matter being compressed and pushed toward the spine. Sometimes, lumbar puncture cannot be performed safely. It is regarded as a safe procedure, but post-dural-puncture headache is a common side effect if a small atraumatic needle is not used.

Normal-pressure hydrocephalus (NPH), also called malresorptive hydrocephalus, is a form of communicating hydrocephalus in which excess cerebrospinal fluid (CSF) occurs in the ventricles, and with normal or slightly elevated cerebrospinal fluid pressure. As the fluid builds up, it causes the ventricles to enlarge and the pressure inside the head to increase, compressing surrounding brain tissue and leading to neurological complications. The disease presents in a classic triad of symptoms, which are memory impairment, urinary frequency, and balance problems/gait deviations. The disease was first described by Salomón Hakim and Adams in 1965.

<span class="mw-page-title-main">Choroid plexus cyst</span> Medical condition

Choroid plexus cysts (CPCs) are cysts that occur within choroid plexus of the brain. They are the most common type of intraventricular cyst, occurring in 1% of all pregnancies.

<span class="mw-page-title-main">Encephalocele</span> Neural tube defect in which the brain protrudes out of the skull

Encephalocele is a neural tube defect characterized by sac-like protrusions of the brain and the membranes that cover it through openings in the skull. These defects are caused by failure of the neural tube to close completely during fetal development. Encephaloceles cause a groove down the middle of the skull, or between the forehead and nose, or on the back side of the skull. The severity of encephalocele varies, depending on its location.

<span class="mw-page-title-main">Dandy–Walker malformation</span> Congenital malformation of the cerebellar vermis

Dandy–Walker malformation (DWM), also known as Dandy–Walker syndrome (DWS), is a rare congenital brain malformation in which the part joining the two hemispheres of the cerebellum does not fully form, and the fourth ventricle and space behind the cerebellum are enlarged with cerebrospinal fluid. Most of those affected develop hydrocephalus within the first year of life, which can present as increasing head size, vomiting, excessive sleepiness, irritability, downward deviation of the eyes and seizures. Other, less common symptoms are generally associated with comorbid genetic conditions and can include congenital heart defects, eye abnormalities, intellectual disability, congenital tumours, other brain defects such as agenesis of the corpus callosum, skeletal abnormalities, an occipital encephalocele or underdeveloped genitalia or kidneys. It is sometimes discovered in adolescents or adults due to mental health problems.

<span class="mw-page-title-main">Ventriculomegaly</span> Increased size of the lateral ventricles

Ventriculomegaly is a brain condition that mainly occurs in the fetus when the lateral ventricles become dilated. The most common definition uses a width of the atrium of the lateral ventricle of greater than 10 mm. This occurs in around 1% of pregnancies. When this measurement is between 10 and 15 mm, the ventriculomegaly may be described as mild to moderate. When the measurement is greater than 15mm, the ventriculomegaly may be classified as more severe.

<span class="mw-page-title-main">Intraventricular hemorrhage</span> Medical condition

Intraventricular hemorrhage (IVH), also known as intraventricular bleeding, is a bleeding into the brain's ventricular system, where the cerebrospinal fluid is produced and circulates through towards the subarachnoid space. It can result from physical trauma or from hemorrhagic stroke.

Bobble-head doll syndrome is a rare neurological movement disorder in which patients, usually children around age 3, begin to bob their head and shoulders forward and back, or sometimes side-to-side, involuntarily, in a manner reminiscent of a bobblehead doll. The syndrome is related to cystic lesions and swelling of the third ventricle in the brain.

Citrobacter koseri, formerly known as Citrobacter diversus, is a Gram-negative non-spore forming, rod-shaped bacterium. It is a facultative anaerobe capable of aerobic respiration. It is motile via peritrichous flagella. It is a member of the family of Enterobacteriaceae. The members of this family are part of the normal flora and commonly found in the digestive tracts of humans and animals. C. koseri may act as an opportunistic pathogen in individuals who are immunocompromised.

References

  1. ↑ Kandel, Eric R. (2013). Principles of neural science (5. ed.). Appleton and Lange: McGraw Hill. p. 1020. ISBN   978-0-07-139011-8.
  2. ↑ "Hydranencephaly: Definition, Information, Diagnosis & Prognosis". 29 September 2012. Retrieved 24 February 2018.
  3. 1 2 3 National Organization for Rare Disorders. "Hydranencephaly". Rare Diseases Information.[ permanent dead link ]
  4. ↑ National Institute of Neurological Conditions and Stroke, NINDS. "Hydranencephaly Information Page". Disorders. Archived from the original on 2016-12-02. Retrieved 2011-06-19.
  5. ↑ Ulmer S, Moeller F, Brockmann MA, Kuhtz-Buschbeck JP, Stephani U, Jansen O (2005). "Living a normal life with the nondominant hemisphere: magnetic resonance imaging findings and clinical outcome for a patient with left-hemispheric hydranencephaly". Pediatrics. 116 (1): 242–5. doi:10.1542/peds.2004-0425. PMID   15995064. S2CID   45671819.
  6. 1 2 3 Kurtz & Johnson, Alfred & Pamela. "Case Number 7: Hydranencephaly". Radiology, 210, 419-422.
  7. 1 2 Dubey, AK Lt Col. "Is it Hydranencephaly-A Variant?" (PDF). MJAFI 2002; 58:338-339. Archived from the original (PDF) on 2014-04-02.
  8. ↑ "Everything Guide to Children with Hydranencephaly" by Brayden Alexander Global Foundation for Hydranencephaly, Incorporated.
  9. ↑ McAbee GN, Chan A, Erde EL (2000). "Prolonged survival with hydranencephaly: report of two patients and literature review" (PDF). Pediatr. Neurol. 23 (1): 80–4. doi:10.1016/S0887-8994(00)00154-5. PMID   10963978.
  10. ↑ S. A. Counter (Dec 15, 2007). "Preservation of brainstem neurophysiological function in hydranencephaly". Journal of the Neurological Sciences . 263 (1–2): 198–207. doi:10.1016/j.jns.2007.06.043. PMID   17719607. S2CID   26948761.
  11. ↑ Rare Disease Day: February 28. "What is a Rare Disease?". Rare Disease. Archived from the original on 2018-10-24.{{cite web}}: CS1 maint: numeric names: authors list (link)
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