| Frontal lobe epilepsy | |
|---|---|
| Specialty | Neurology |
| Treatment | |
| Medication | Antiepileptics (oxcarbazepine, carbamazepine, phenytoin) |
Frontal lobe epilepsy (FLE) is a neurological disorder that is characterized by brief, recurring seizures arising in the frontal lobes of the brain, that often occur during sleep. [1] It is the second most common type of epilepsy after temporal lobe epilepsy (TLE), and is related to the temporal form in that both forms are characterized by partial (focal) seizures. [2]
Partial seizures occurring in the frontal lobes can occur in one of two different forms: either “focal aware”, the old term was simple partial seizures (that do not affect awareness or memory) “focal unaware” the old term was complex partial seizures (that affect awareness or memory either before, during or after a seizure). The symptoms and clinical manifestations of frontal lobe epilepsy can differ depending on which specific area of the frontal lobe is affected. [2]
The onset of a seizure may be hard to detect since the frontal lobes contain and regulate many structures and functions about which relatively little is known. [3] Due to the lack of knowledge surrounding the functions associated with the frontal lobes, seizures occurring in these regions of the brain may produce unusual symptoms which can often be misdiagnosed as a psychiatric disorder, non-epileptic seizure or a sleep disorder. [3]
During the onset of a seizure, the patient may exhibit abnormal body posturing, sensorimotor tics, or other abnormalities in motor skills. [3] In some cases, uncontrollable laughing or crying may occur during a seizure. [2] Affected persons may or may not be aware that they are behaving in an abnormal manner, depending on the patient and type of seizure. [2] A brief period of confusion known as a postictal state may sometimes follow a seizure occurring in the frontal lobes. [2] However, these postictal states are often undetectable and generally do not last as long as the periods of confusion following seizures that occur in the temporal lobes. [2]
There are many different causes of frontal lobe epilepsy ranging from genetics to head trauma that result in lesions in the frontal lobes. [4] Although frontal lobe epilepsy is often misdiagnosed, tests such as prolonged EEG monitoring, video EEG and/or an MRI scan of the frontal lobes can be administered in order to reveal the presence of a tumor or vascular malformation. [4] Unlike most epileptic EEGs, the abnormalities in FLE EEGs precede the physical onset of the seizure and aid in localization of the seizure's origin. [4] Medications such as anti-epileptic drugs can typically control the onset of seizures, however, if medications are ineffective the patient may undergo surgery to have focal areas of the frontal lobe removed. [4]
Signs and symptoms of frontal lobe seizures may include [3]
Epileptic symptoms are frequently the product of the spread of overactivation occurring within one central foci that travels to lateral brain regions thereby causing an array of symptoms. Due to the massive amount of diversity in both the cognitive and motor functions that occur within the frontal lobes, there is an immense variety in the types of symptoms that can arise from epileptic seizures based on the side and topography of the focal origin. In general these symptoms can range anywhere from asymmetric and abnormal body positioning to repetitive vocal outbursts and repetitive jerking movements. [3] The symptoms typically come in short bursts that last less than a minute and often occur while a patient is sleeping. [5] In most cases, a patient will experience a physical or emotional aura of tingling, numbness or tension prior to a seizure occurring. [6] Fear is associated with temporal and frontal lobe epilepsies, but in FLE the fear is predominantly expressed on the person's face whereas in TLE the fear is subjective and internal, not perceptible to the observer. [4]
Tonic posture and clonic movements are common symptoms among most of the areas of the frontal lobe, therefore the type of seizures associated with frontal lobe epilepsy are commonly called tonic-clonic seizures. Dystonic motor movements are common to both TLE and FLE, but are usually the first symptom in FLE episodes where they are quite brief and do not affect consciousness. The seizures are complex partial, simple partial, secondarily generalized or a combination of the three. These partial seizures are often misdiagnosed as psychogenic seizures. [4]
A wide range of more specific symptoms arise when different parts of the frontal cortex are affected. [2]
Advancements in technology, has given rise to newer, more efficient methods of diagnosis, most prominent being in the domain of neuroimaging. [7] The high spatial resolution from fMRI has implications on certain brain regions contributing to memory. [7] The usage of task fMRI for examination of memory or other higher cognitive networks may also be used to predict ictal onset zone(s) in patients with FLE, giving the advantage of refinement of patient-specific analyses. [7] The use of multi-modal approaches in association with neuroimaging techniques like fMRI and MEG or EEG will be informative in characterizing atypical functional brain networks in FLE. [7] But, difficulty remains in the evaluation of potential compensatory mechanisms between patients with FLE with normal and impaired memory, without properly characterizing transfer of information during memory tasks. [7]
Episodes that include complex hyperactivity of the proximal portions of the limbs that lead to increased overall motor activity are called hypermotor seizures. When associated with bizarre movements and vocalizations these seizures are often misdiagnosed as psychogenic or functional sezures or other episodic movement disorders such as psychogenic movement disorders, familial paroxysmal dystonic choreoathetosis, paroxysmal kinesogenic choreoathetosis, or episodic ataxia type 1. [4] Hypermotor seizure in children are often confused with pavor nocturnus (night terrors). Paroxysmal nocturnal dystonia or hypnogenic paroxysmal dystonia are other names given to describe FLE symptoms but are simply just FLE. [4]
Autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) is the best understood form of frontal lobe epilepsy but is often misdiagnosed as sleep apnea. Both disorders are characterized by awakening during the night which leads to daytime sleepiness. Some symptoms of sleep apnea overlap with those of ADNFLE, such as sudden awakening accompanied by a feeling of choking and on occasion motor activity which makes diagnosis difficult based on symptoms alone. Video surveillance as well as EEG is occasionally needed to differentiate between the two disorders. It has been reported that sleep apnea might be associated with epilepsy which would account for some of the misdiagnoses. [4]
The origins of frontal lobe seizures can be different deviations. [8] One of the major reasons for FLE is abnormal cognitive development or sometimes congenital abnormal brain development. [8] Other causes are tumors, head trauma, and genetics. [9]
Tumors account for about one-third of all frontal lobe epilepsy cases. [9]
Seizures originating directly from head trauma usually occur within a few months, but occasionally they can take years to manifest. [2]
Due to the difference in brain processing and function as well as various surface anatomy landmarks, the frontal lobes have traditionally been divided into two major areas known as the precentral cortex and prefrontal cortex.[ citation needed ]
The precentral cortex (Brodmann area 6) is an area of the frontal cortex that is located directly anterior to the central sulcus and includes both the primary motor cortex and the supplementary motor area. [6] Inputs that project to both of these areas arise from a variety of locations in the brain that integrate sensory stimuli including the primary motor cortex, the thalamus and corticospinal projections. [6] These two areas along with several other main functional areas control both the preparation of motor movement as well as the execution of movements. These main functional areas are crucial to the development of the motor related symptoms associated with frontal lobe epilepsy focally when seizures are located within these defined areas. [10] The major functional areas include:
The prefrontal cortex, the most anterior region of the brain, comprises several key areas that are particularly important for higher mental functions that control various aspects of human personality including anticipation and planning, initiative/judgement, memory and the control of decision making. [13] Damage or lesions to this region of the brain can result in major changes in personality. A classic example is Phineas Gage, who exhibited a change in behavior after one or both frontal lobes were destroyed by a large iron bar accidentally driven through his head (though Gage, despite conventional presentations of his case, did not exhibit the aggression, antisocial behavior, or loss of impulse control sometimes reported in patients with similar injuries).
There are two main regions of the prefrontal cortex that each control various aspects of behavior and personality:
Epilepsy has a substantial impact on the quality of life of the individuals that are affected by it, yet there is lack of proper examination of social cognitive functions. Physicians and researchers are coming to understand that the impact on the quality of life of the patient is as important as the effects of the seizures. [15] Quality of life questionnaires and other assessment tools have been created to help quantify quality of life for individual patients. They consider such factors as physical health (including numbers and severity of seizures, medication side effects etc.), mental health, social relationships, lifestyle, role activities and life fulfillment. [16] A Center for Disease Control study reported that people with seizures were more likely to have lower education levels, higher unemployment, higher levels of pain, hypersomnia/insomnia, increased psychological distress and social isolation/connection issues. [17] Some of the issues which impact quality of life for people with epilepsy are: ability to drive and travel, the ability to date, marry and have children, the ability to have a job and independence, the ability to have an education and learn, and the ability to have good health and mental functioning. [18] Future research is needed to find ways of not only controlling frontal lobe seizures, but of also addressing the specific quality-of-life issues that plague those with frontal lobe epilepsy, especially as studies show a higher emotional recognition anomaly in cases of FLE, compared to TLE. [19]
There are several different ways to treat frontal lobe epileptic seizures, however, the most common form of treatment is through the use of anticonvulsant medications that help to prevent seizures from occurring. In some cases, however, when medications are ineffective, a neurologist may choose to operate on the patient in order to remove the focal area of the brain in which the seizures are occurring. Other treatments that can be administered to aid in reducing the occurrence of seizures include the implementation of a specific, regimented diet and/or the implantation of a vagus nerve stimulator, or deep brain stimulation (DBS).
There are many anticonvulsants available for the treatment of different forms of epilepsy and include oxcarbazepine, carbamazepine, and phenytoin. [2] Benzodiazepines are often used in emergency settings for severe convulsions, and may also be used in combination with anticonvulsants. These include lorazepam, diazepam and clonazepam
KCNT1 pathogenic variant associated ADNFLE can be managed by treatment with quinidine, [36] and ADNFLE associated with CHRNA4 shows better responsiveness to zonisamide. [37]
When both the amount and severity of seizures becomes uncontrollable and seizures remain resistant to the various anticonvulsants, a patient most likely will be considered for epilepsy surgery. [38] But, while performing it, there is the need for identifying or pinpointing the exact location of the seizure in the brain. [38] This, in recent times have been aided by some of the modern techniques such as, SISCOM i.e., subtraction ictal SPECT co registered to MRI, SPECT i.e. single-photon emission computerized tomography, brain mapping performed before the surgery and functional MRI (fMRI), especially for the language area mapping. [38]
Surgeries include, a frontal lobectomy. [39] This procedure involves the removal of focal regions of the frontal lobes that have been identified as being problematic for the patient. It has been found that around 30% to 50% of patients that undergo a frontal lobectomy will forever be free from seizures that cause a loss of consciousness or cause abnormal movements. [40] However, frontal lobectomy and MCD contribute to lower seizure controls. But, in children with conditions like Sturge–Weber syndrome (SWS) or tumors, there is report of greater seizure control rates.
If on the other hand, the seizures occur in an area that is too vital to remove (such as areas that control motor, sensory or language functions), then the surgeon will perform a procedure known as a multiple subpial transection. [41] This procedure involves making a series of cuts that surround the focal region where the seizures have originated. [41] By making cuts surrounding the focal region, the surgeon is able to isolate that specific section of the brain and prevent electrical impulses from being able to travel horizontally to other areas of the brain. [41]
Vagus nerve stimulation (VNS) is a procedure that can be performed to help prevent the reoccurrence of frontal lobe seizures. It involves the implanting of a stimulator on the vagus nerve. [42] The stimulator is a device that is inserted directly under the skin, and can be controlled directly by the user. [42] When the onset of an aura is felt, the stimulator can be activated which provides stimulation to the left vagus nerve (the left vagus nerve is used because the right nerve plays a role in cardiac function). [43] Although little is understood about the exact mechanism for vagal nerve stimulation, it has been proven to be a successful treatment that can often terminate seizures before they begin. [43] It has the potential of being helpful in patients with resistance to medications. [43]
Deep brain stimulation (DBS) is another procedure that can be used that utilizes a mechanism similar to that of a cardiac pacemaker. [3]
Surgeries have been used as a treatment for FLE, however, meta-analyses have shown that proper etiological studies are important to give best postoperative results, with children <3 years of age showing pathology and location of the surgery as important factors. It also showed the malformation of cortical development (MCD) induced FLE traced down to worst postoperative conditions, hence, poor accuracy and efficacy. [44]
The use of a ketogenic diet is recommended for those with intractable epilepsy. [45] A ketogenic diet is a high-fat, low-carbohydrate diet recommended to be followed when appropriate, along with prescribed anticonvulsants. This diet was designed in order to mimic many of the effects that starvation has on the metabolic functioning of the body. [45] By limiting the amount of carbohydrates and increasing the amount of exogenous fats available to the metabolism, the body will create an excess of water-soluble compounds known as ketone bodies. [45] Although the mechanism of action is still unknown, it is believed that these excessive amounts of ketone bodies become the brain's main source of energy and in turn are able to suppress the frequency of seizure occurrence. [45]
Epilepsy is a relatively common disorder, affecting between 0.5–1% of the population, [46] and frontal lobe epilepsy accounts for about 1–2% of all epilepsies. [4] The most common subdivision of epilepsy is symptomatic partial epilepsy, which causes simple partial seizures, and can be further divided into temporal and frontal lobe epilepsy. Although the exact number of cases of frontal lobe epilepsy is not currently known, it is known that FLE is the less common type of partial epilepsy, accounting for 20–30% of operative procedures involving intractable epilepsy. [47] Patients with medically refractive epilepsy, over a fraction of one-fourth have been diagnosed with FLE, only one-third of which have been found to get relief from seizures by surgical interventions. [48] The disorder also has no gender or age bias, affecting males and females of all ages. In a recent study, the mean subject age with frontal lobe epilepsy was 28.5 years old, and the average age of epilepsy onset for left frontal epilepsy was 9.3 years old whereas for right frontal epilepsy it was 11.1 years old. [2]
Over the past decade or so, researchers have been attempting to discover less invasive, safer and more efficient technologies that enable surgeons to remove epileptogenic focal zones without causing any damage to neighboring cortical areas. One such technology that has emerged and has great promise, is the use of gamma knife radiosurgery to either excise a brain tumor or repair a vascular malformation. [49]
In Gamma Knife radiosurgery, intersecting gamma radiation beams are applied directly to the tumor site or vascular malformation site that had been established using neuroimaging. [49] Although each beam itself is not strong enough to damage brain tissue, when the beams intersect they are strong enough to destroy the specific brain tissue that is to be excised. This process is extremely efficient and entirely non-invasive and is therefore much safer than actual neurosurgery itself.
Recently researchers and surgeons alike have begun to use Gamma Knife radiosurgery to treat cases of epilepsy by removing tumors responsible for causing the seizures. [50] [51] The early success rates in being able to alleviate seizures seem to be similar to those of temporal resective surgery however Gamma Knife radiosurgery has less associated risk factors. [51] Current research on this topic is aimed at improving the technique in order to increase success rates as well as developing non-invasive forms of physiologic monitoring in order to determine the epileptogenic focus conclusively. [51]
Another way of understanding or studying FLE, highly under study is the network approach. When conventional imaging does not show the structural lesions, high frequency oscillation (HFO) analysis shows the pathophysiology, locally at the neural circuit level. Genetic analysis along with neuroimaging like fMRI, EEG, MEG, and in-depth semiological analysis, aids in the network approach study of FLE, both at micro and macro levels, giving it a comprehensive view. [48]
A convulsion is a medical condition where the body muscles contract and relax rapidly and repeatedly, resulting in uncontrolled shaking. Because epileptic seizures typically include convulsions, the term convulsion is often used as a synonym for seizure. However, not all epileptic seizures result in convulsions, and not all convulsions are caused by epileptic seizures. Non-epileptic convulsions have no relation with epilepsy, and are caused by non-epileptic seizures.
The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere. It is parted from the parietal lobe by a groove between tissues called the central sulcus and from the temporal lobe by a deeper groove called the lateral sulcus. The most anterior rounded part of the frontal lobe is known as the frontal pole, one of the three poles of the cerebrum.
Hypergraphia is a behavioral condition characterized by the intense desire to write or draw. Forms of hypergraphia can vary in writing style and content. It is a symptom associated with temporal lobe changes in epilepsy and in Geschwind syndrome. Structures that may have an effect on hypergraphia when damaged due to temporal lobe epilepsy are the hippocampus and Wernicke's area. Aside from temporal lobe epilepsy, chemical causes may be responsible for inducing hypergraphia.
Epilepsia partialis continua is a rare type of brain disorder in which a patient experiences recurrent motor epileptic seizures that are focal, and recur every few seconds or minutes for extended periods. It is sometimes called Kozhevnikov's epilepsia named after Russian psychiatrist Aleksei Yakovlevich Kozhevnikov who first described this type of epilepsy.
Witzelsucht is a set of pure and rare neurological symptoms characterized by a tendency to make puns, or tell inappropriate jokes or pointless stories in socially inappropriate situations. It makes one unable to read sarcasm.
An aura is a perceptual disturbance experienced by some with epilepsy or migraine. An epileptic aura is a seizure.
Psychogenic non-epileptic seizures (PNES), which have been more recently classified as functional seizures, are events resembling an epileptic seizure, but without the characteristic electrical discharges associated with epilepsy. PNES fall under the category of disorders known as functional neurological disorders (FND), also known as conversion disorders. These are typically treated by psychologists or psychiatrists. PNES has previously been called pseudoseizures, psychogenic seizures, and hysterical seizures, but these terms have fallen out of favor.
Automatic behavior is the spontaneous production of purposeless verbal or motor behavior without conscious self-control or self-censorship. This condition can be observed in a variety of contexts, including schizophrenia, psychogenic fugue, Tourette syndrome, epilepsy, narcolepsy, or in response to a traumatic event.
Focal seizures are seizures which affect initially only one hemisphere of the brain. The brain is divided into two hemispheres, each consisting of four lobes – the frontal, temporal, parietal and occipital lobes. A focal seizure is generated in and affects just one part of the brain – a whole hemisphere or part of a lobe. Symptoms will vary according to where the seizure occurs. When seizures occur in the frontal lobe the patient may experience a wave-like sensation in the head. When seizures occur in the temporal lobe, a feeling of déjà vu may be experienced. When seizures are localized to the parietal lobe, a numbness or tingling may occur. With seizures occurring in the occipital lobe, visual disturbances or hallucinations have been reported.
In the field of neurology, temporal lobe epilepsy is an enduring brain disorder that causes unprovoked seizures from the temporal lobe. Temporal lobe epilepsy is the most common type of focal onset epilepsy among adults. Seizure symptoms and behavior distinguish seizures arising from the medial temporal lobe from seizures arising from the lateral (neocortical) temporal lobe. Memory and psychiatric comorbidities may occur. Diagnosis relies on electroencephalographic (EEG) and neuroimaging studies. Anticonvulsant medications, epilepsy surgery and dietary treatments may improve seizure control.
Electrocorticography (ECoG), a type of intracranial electroencephalography (iEEG), is a type of electrophysiological monitoring that uses electrodes placed directly on the exposed surface of the brain to record electrical activity from the cerebral cortex. In contrast, conventional electroencephalography (EEG) electrodes monitor this activity from outside the skull. ECoG may be performed either in the operating room during surgery or outside of surgery. Because a craniotomy is required to implant the electrode grid, ECoG is an invasive procedure.
Frontal lobe disorder, also frontal lobe syndrome, is an impairment of the frontal lobe of the brain due to disease or frontal lobe injury. The frontal lobe plays a key role in executive functions such as motivation, planning, social behaviour, and speech production. Frontal lobe syndrome can be caused by a range of conditions including head trauma, tumours, neurodegenerative diseases, neurodevelopmental disorders, neurosurgery and cerebrovascular disease. Frontal lobe impairment can be detected by recognition of typical signs and symptoms, use of simple screening tests, and specialist neurological testing.
Foix–Chavany–Marie Syndrome (FCMS), also known as bilateral opercular syndrome, is a neuropathological disorder characterized by paralysis of the facial, tongue, pharynx, and masticatory muscles of the mouth that aid in chewing. The disorder is primarily caused by thrombotic and embolic strokes, which cause a deficiency of oxygen in the brain. As a result, bilateral lesions may form in the junctions between the frontal lobe and temporal lobe, the parietal lobe and cortical lobe, or the subcortical region of the brain. FCMS may also arise from defects existing at birth that may be inherited or nonhereditary. Symptoms of FCMS can be present in a person of any age and it is diagnosed using automatic-voluntary dissociation assessment, psycholinguistic testing, neuropsychological testing, and brain scanning. Treatment for FCMS depends on the onset, as well as on the severity of symptoms, and it involves a multidisciplinary approach.
Epilepsy surgery involves a neurosurgical procedure where an area of the brain involved in seizures is either resected, ablated, disconnected or stimulated. The goal is to eliminate seizures or significantly reduce seizure burden. Approximately 60% of all people with epilepsy have focal epilepsy syndromes. In 15% to 20% of these patients, the condition is not adequately controlled with anticonvulsive drugs. Such patients are potential candidates for surgical epilepsy treatment.
Sleep-related hypermotor epilepsy (SHE), previously known as nocturnal frontal lobe epilepsy, is a form of focal epilepsy characterized by seizures which arise during sleep. The seizures are most typically characterized by complex motor behaviors. It is a relatively uncommon form of epilepsy that constitutes approximately 9-13% of cases. This disorder is associated with cognitive impairment in at least half of patients as well as excessive daytime sleepiness due to poor sleep quality. This disorder is sometimes misdiagnosed as a non-epileptic sleep disorder. There are many potential causes of SHE including genetic, acquired injuries and structural abnormalities.
Epilepsy is a neurological condition of recurrent episodes of unprovoked epileptic seizures. A seizure is an abnormal neuronal brain activity that can cause intellectual, emotional, and social consequences. Epilepsy affects children and adults of all ages and races, it is one of the most common neurological disorders of the nervous system. As well as, this condition is more common among children than adults affecting about 6 out of 1000 US children that are between the age of 0 to 5 years old. The epileptic seizures can be of different types depending on the part of the brain that was affected, seizures are classified in 2 main types partial seizure or genralized seizure.
People with epilepsy may be classified into different syndromes based on specific clinical features. These features include the age at which seizures begin, the seizure types, and EEG findings, among others. Identifying an epilepsy syndrome is useful as it helps determine the underlying causes as well as deciding what anti-seizure medication should be tried. Epilepsy syndromes are more commonly diagnosed in infants and children. Some examples of epilepsy syndromes include benign rolandic epilepsy, childhood absence epilepsy and juvenile myoclonic epilepsy. Severe syndromes with diffuse brain dysfunction caused, at least partly, by some aspect of epilepsy, are also referred to as epileptic encephalopathies. These are associated with frequent seizures that are resistant to treatment and severe cognitive dysfunction, for instance Lennox-Gastaut syndrome and West syndrome.
Cerebral diplopia or polyopia describes seeing two or more images arranged in ordered rows, columns, or diagonals after fixation on a stimulus. The polyopic images occur monocular bilaterally and binocularly, differentiating it from ocular diplopia or polyopia. The number of duplicated images can range from one to hundreds. Some patients report difficulty in distinguishing the replicated images from the real images, while others report that the false images differ in size, intensity, or color. Cerebral polyopia is sometimes confused with palinopsia, in which multiple images appear while watching an object. However, in cerebral polyopia, the duplicated images are of a stationary object which are perceived even after the object is removed from the visual field. Movement of the original object causes all of the duplicated images to move, or the polyopic images disappear during motion. In palinoptic polyopia, movement causes each polyopic image to leave an image in its wake, creating hundreds of persistent images (entomopia).
Occipital epilepsy is a neurological disorder that arises from excessive neural activity in the occipital lobe of the brain that may or may not be symptomatic. Occipital lobe epilepsy is fairly rare, and may sometimes be misdiagnosed as migraine when symptomatic. Epileptic seizures are the result of synchronized neural activity that is excessive, and may stem from a failure of inhibitory neurons to regulate properly.
Organic personality disorder (OPD) or secondary personality change, is a condition described in the ICD-10 and ICD-11 respectively. It is characterized by a significant personality change featuring abnormal behavior due to an underlying traumatic brain injury or another pathophysiological medical condition affecting the brain. Abnormal behavior can include but is not limited to apathy, paranoia and disinhibition.
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