The diagnosis can be confirmed when the characteristic centrotemporal spikes are seen on electroencephalography (EEG). Typically, high-voltage spikes followed by slow waves are seen. Given the nocturnal activity, a sleep EEG can often be helpful. Technically, the label "benign" can only be confirmed if the child's development continues to be normal during follow-up. Neuroimaging, usually with an MRI scan, is only advised for cases with atypical presentation or atypical findings on clinical examination or EEG.

The disorder should be differentiated from several other conditions, especially centrotemporal spikes without seizures, centrotemporal spikes with local brain pathology, central spikes in Rett syndrome and fragile X syndrome, malignant Rolandic epilepsy, temporal lobe epilepsy and Landau-Kleffner syndrome.

The most important factor in diagnosing a patient with vertiginous epilepsy is the subject’s detailed description of the episode. However, due to the associated symptoms of the syndrome a subject may have difficulty remembering the specifics of the experience. This makes it difficult for a physician to confirm the diagnosis with absolute certainty. A questionnaire may be used to help patients, especially children, describe their symptoms. Clinicians may also consult family members for assistance in diagnosis, relying on their observations to help understand the episodes. In addition to the description of the event, neurological, physical and hematologic examinations are completed to assist in diagnosis. For proper diagnosis, an otological exam (examination of the ear) should also be completed to rule out disorders of the inner ear, which could also be responsible for manifestations of vertigo. This may include an audiological assessment and vestibular function test. During diagnosis, history-taking is essential in determining possible causes of vertiginous epilepsy as well as tracking the progress of the disorder over time.

Other means used in diagnosis of vertiginous epilepsy include:

- Electroencephalography (EEG)

- Magnetic resonance imaging (MRI)

- Positron emission tomography (PET)

- Neuropsychological testing

The EEG measures electrical activity in the brain, allowing a physician to identify any unusual patterns. While EEGs are good for identifying abnormal brain activity is it not helpful in localizing where the seizure originates because they spread so quickly across the brain. MRIs are used to look for masses or lesions in the temporal lobe of the brain, indicating possible tumors or cancer as the cause of the seizures. When using a PET scan, a physician is looking to detect abnormal blood flow and glucose metabolism in the brain, which is visible between seizures, to indicate the region of origin.

The diagnosis or suspicion of LGS is often a question of probability rather than certainty. This is because the varied presentations of LGS share features with other disorders, many of which may be said to have overlapping characteristics.

The diagnosis is more obvious when the epilepsy has frequent and manifold attacks, with the classic pattern on the electro-encephalogram (EEG); the latter is a slowed rhythm with Spike-wave-pattern, or with a multifocal and generalizing Sharp-slow-wave-discharges at 1.5–2.5 Hz. During sleep, frequently, tonic patterns can be seen. But variations of these patterns are known in patients with no diagnosis other than LGS, and they can differ bilaterally, and from time to time, within the same patient.

General medical investigation usually reveals developmental delay and cognitive deficiencies in children with true LGS. These may precede development of seizures, or require up to two years after the seizures begin, in order to become apparent.

Exclusion of organic or structural brain lesions is also important in establishing a correct diagnosis of LGS; this may require magnetic resonance imaging (MRI) or computerized tomography (CT). An important differential diagnosis is 'Pseudo-Lennox-Syndrome', which differs from LGS, in that there are no tonic seizures; sleeping EEG provides the best basis for distinguishing between the two.

Diagnosis is typically made upon patient history, although EEG recordings can be confirmatory if they occur during attacks.

Intravenous immunoglobulin therapy has been used in Lennox–Gastaut syndrome as early as 1986, when van Rijckevorsel-Harmant and colleagues used it in seven patients with ostensibly idiopathic LGS and saw EEG improvement and decreased seizure frequency in six of them.

An electroencephalogram (EEG) can assist in showing brain activity suggestive of an increased risk of seizures. It is only recommended for those who are likely to have had an epileptic seizure on the basis of symptoms. In the diagnosis of epilepsy, electroencephalography may help distinguish the type of seizure or syndrome present. In children it is typically only needed after a second seizure. It cannot be used to rule out the diagnosis and may be falsely positive in those without the disease. In certain situations it may be useful to perform the EEG while the affected individual is sleeping or sleep deprived.

Diagnostic imaging by CT scan and MRI is recommended after a first non-febrile seizure to detect structural problems in and around the brain. MRI is generally a better imaging test except when bleeding is suspected, for which CT is more sensitive and more easily available. If someone attends the emergency room with a seizure but returns to normal quickly, imaging tests may be done at a later point. If a person has a previous diagnosis of epilepsy with previous imaging, repeating the imaging is usually not needed even if there are subsequent seizures.

For adults, the testing of electrolyte, blood glucose and calcium levels is important to rule out problems with these as causes. An electrocardiogram can rule out problems with the rhythm of the heart. A lumbar puncture may be useful to diagnose a central nervous system infection but is not routinely needed. In children additional tests may be required such as urine biochemistry and blood testing looking for metabolic disorders.

A high blood prolactin level within the first 20 minutes following a seizure may be useful to help confirm an epileptic seizure as opposed to psychogenic non-epileptic seizure. Serum prolactin level is less useful for detecting focal seizures. If it is normal an epileptic seizure is still possible and a serum prolactin does not separate epileptic seizures from syncope. It is not recommended as a routine part of the diagnosis of epilepsy.

The prognosis of ICOE-G is unclear, although available data indicate that remission occurs in 50–60% of patients within 2–4 years of onset. Seizures show a dramatically good response to carbamazepine in more than 90% of patients. However, 40–50% of patients may continue to have visual seizures and infrequent secondarily generalized convulsions, particularly if they have not been appropriately treated with antiepileptic drugs.

The differential diagnosis of ICOE-G is mainly from symptomatic occipital epilepsy and migraine where misdiagnosis is high. The differential diagnosis from migraine should be easy because elementary visual hallucinations of occipital seizures develop rapidly within seconds, are brief in duration (2–3 minutes) are usually colored and circular. These are fundamentally different from the visual aura of migraine which develops slowly in minutes, is longer lasting ≥5 minutes and mainly achromatic with linear patterns.

Symptomatic occipital epilepsy often imitates ICOE-G; neuroophthalmological examination and brain imaging may be normal. Thus, high resolution MRI is required to detect subtle lesions.

The differentiation of ICOE-G from Panayiotopoulos syndrome is straightforward. The seizures of ICOE-G are purely occipital, brief, frequent and diurnal. Conversely seizures in Panayiotopoulos syndrome manifest with autonomic manifestations, they are lengthy and infrequent; visual symptoms are rare and not the sole manifestation of a seizure.

Some features are more or less likely to suggest PNES but they are not conclusive and should be considered within the broader clinical picture. Features that are common in PNES but rarer in epilepsy include: biting the tip of the tongue, seizures lasting more than 2 minutes (easiest factor to distinguish), seizures having a gradual onset, a fluctuating course of disease severity, the eyes being closed during a seizure, and side to side head movements. Features that are uncommon in PNES include automatisms (automatic complex movements during the seizure), severe tongue biting, biting the inside of the mouth, and incontinence.

If a patient with suspected PNES has an episode during a clinical examination, there are a number of signs that can be elicited to help support or refute the diagnosis of PNES. Compared to patients with epilepsy, patients with PNES will tend to resist having their eyes forced open (if they are closed during the seizure), will stop their hands from hitting their own face if the hand is dropped over the head, and will fixate their eyes in a way suggesting an absence of neurological interference. Mellers et al. warn that such tests are neither conclusive nor impossible for a determined patient with factitious disorder to "pass" through faking convincingly.

The differential diagnosis of PNES firstly involves ruling out epilepsy as the cause of the seizure episodes, along with other organic causes of non-epileptic seizures, including syncope, migraine, vertigo, anoxia, hypoglycemia, and stroke. However, between 5-20% of patients with PNES also have epilepsy. Frontal lobe seizures can be mistaken for PNES, though these tend to have shorter duration, stereotyped patterns of movements and occurrence during sleep. Next, an exclusion of factitious disorder (a subconscious somatic symptom disorder, where seizures are caused by psychological reasons) and malingering (simulating seizures intentionally for conscious personal gain – such as monetary compensation or avoidance of criminal punishment) is conducted. Finally other psychiatric conditions that may superficially resemble seizures are eliminated, including panic disorder, schizophrenia, and depersonalisation disorder.

The most conclusive test to distinguish epilepsy from PNES is long term video-EEG monitoring, with the aim of capturing one or two episodes on both videotape and EEG simultaneously (some clinicians may use suggestion to attempt to trigger an episode). Conventional EEG may not be particularly helpful because of a high false-positive rate for abnormal findings in the general population, but also of abnormal findings in patients with some of the psychiatric disorders that can mimic PNES. Additional diagnostic criteria are usually considered when diagnosing PNES from long term video-EEG monitoring because frontal lobe epilepsy may be undetectable with surface EEGs.

Following most tonic-clonic or complex partial epileptic seizures, blood levels of serum prolactin rise, which can be detected by laboratory testing if a sample is taken in the right time window. However, due to false positives and variability in results this test is relied upon less frequently.

The prognosis for Rolandic seizures is invariably excellent, with probably less than 2% risk of developing absence seizures and less often GTCS in adult life.

Remission usually occurs within 2–4 years from onset and before the age of 16 years. The total number of seizures is low, the majority of patients having fewer than 10 seizures; 10–20% have just a single seizure. About 10–20% may have frequent seizures, but these also remit with age.

Children with Rolandic seizures may develop usually mild and reversible linguistic, cognitive and behavioural abnormalities during the active phase of the disease. These may be worse in children with onset of seizures before 8 years of age, high rate of occurrence and multifocal EEG spikes.

The development, social adaptation and occupations of adults with a previous history of Rolandic seizures were found normal.

Diagnosis of epilepsy can be difficult. A number of other conditions may present very similar signs and symptoms to seizures, including syncope, hyperventilation, migraines, narcolepsy, panic attacks and psychogenic non-epileptic seizures (PNES). In particular a syncope can be accompanied by a short episode of convulsions. Nocturnal frontal lobe epilepsy, often misdiagnosed as nightmares, was considered to be a parasomnia but later identified to be an epilepsy syndrome. Attacks of the movement disorder paroxysmal dyskinesia may be taken for epileptic seizures. The cause of a drop attack can be, among many others, an atonic seizure.

Children may have behaviors that are easily mistaken for epileptic seizures but are not. These include breath-holding spells, bed wetting, night terrors, tics and shudder attacks. Gastroesophageal reflux may cause arching of the back and twisting of the head to the side in infants, which may be mistaken for tonic-clonic seizures.

Misdiagnosis is frequent (occurring in about 5 to 30% of cases). Different studies showed that in many cases seizure-like attacks in apparent treatment-resistant epilepsy have a cardiovascular cause. Approximately 20% of the people seen at epilepsy clinics have PNES and of those who have PNES about 10% also have epilepsy; separating the two based on the seizure episode alone without further testing is often difficult.

There have been early and consistent strategies for measurement to better understand vertiginous epilepsy including caloric reflex test, posture and gait, or rotational experimentation.

In Japan, Kaga et al prepared a longitudinal study of rotation tests comparing congenital deafness and children with delayed acquisition of motor system skills. They were able to demonstrate the development of post-rotation nystagmus response from the frequency of beat and duration period from birth to six years to compare to adult values. Overall, the study demonstrated that some infants from the deaf population had impaired vestibular responses related to head control and walking age. A side interpretation included the evaluation of the vestibular system in reference to matching data with age.

Research in this area of medicine is limited due to its lacking need for urgent attention. But, the American Hearing Research Foundation (AHRF) conducts studies in which they hope to make new discoveries to help advance treatment of the disease and possibly one day prevent vertiginous seizures altogether.

The ring 20 abnormality may be limited to as few as 5% of cells, so a screen for chromosomal mosaicism is critical. Newer array technology will not detect the ring chromosome and the standard metaphase chromosome analysis has been recommended. A karyotype analysis examining at least 50 cells should be requested to properly detect mosaicism.

Continuous prophylactic antiepileptic drug (AED) treatment may not be needed particularly for children with only 1-2 or brief seizures. This is probably best reserved for children whose seizures are unusually frequent, prolonged, distressing, or otherwise significantly interfering with the child’s life. There is no evidence of superiority of monotherapy with any particular common AED.

Autonomic status epilepticus in the acute stage needs thorough evaluation for proper diagnosis and assessment of the neurologic/autonomic state of the child. "Rescue" benzodiazepines are commonly used to terminate it. Aggressive treatment should be avoided because of the risk of iatrogenic complications, including cardiovascular arrest. There is some concern that intravenous lorazepam and/or diazepam may precipitate cardiovascular arrest. Early parental treatment is more effective than late emergency treatment. Buccal midazolam is probably the first choice medication for out of hospital termination of autonomic status epilepticus which should be administered as soon as the child shows evidence of onset of its habitual autonomic seizures.

Parental education about Panayiotopoulos syndrome is the cornerstone of correct management. The traumatizing, sometimes long-lasting effect on parents is significant particularly because autonomic seizures may last for many hours compounded by physicians’ uncertainty regarding diagnosis, management, and prognosis.

In epilepsy surgery a distinction can be made between resective and disconnective procedures. In a resective procedure the area of the brain that causes the seizures is removed. In a disconnective procedure the neural connections in the brain that allow the seizures to spread are disconnected. In most cases epilepsy surgery is only an option when the area of the brain that causes the seizures - the so-called epileptic focus can be clearly identified and is not responsible for critical functions such as language. Several imaging techniques such as magnetic resonance tomography and functional techniques like electrocorticography are used to demarcate the epileptic focus clearly.

The most important determinant of the neurodiagnostic procedures is the state of the child at the time of first medical attendance:

(1) The child has a brief or lengthy seizure of Panayiotopoulos syndrome but fully recovers prior to arriving in the accident and emergency department or being seen by a physician. A child with the distinctive clinical features of Panayiotopoulos syndrome, particularly ictus emeticus and lengthy seizures, may not need any investigations other than EEG. However, because approximately 10% to 20% of children with similar seizures may have brain pathology, an MRI may be needed.

(2) The child with a typical lengthy seizure of Panayiotopoulos syndrome partially recovers while still in a postictal stage, tired, mildly confused, and drowsy on arrival to the accident and emergency department or when seen by a physician. The child should be kept under medical supervision until fully recovered, which usually occurs after a few hours of sleep. Then guidelines are the same as in (1) above.

(3) The child is brought to the accident and emergency department or is seen by a physician while ictal symptoms continue. This is the most difficult and challenging situation. There may be dramatic symptoms accumulating in succession, which demand rigorous and experienced evaluation. The seizure may be very dramatic, with symptoms accumulating in succession, convulsions may occur and a child who becomes unresponsive and flaccid demands rigorous and experienced evaluation. The most prominent acute disorders in the differential diagnosis include encephalitis or an encephalopathic state from causes such as infections, metabolic derangement (either inborn error or others such as hypoglycaemia), raised intracranial pressure and so forth. A history of a previous similar seizure is reassuring and may prevent further procedures.

Electroencephalography (EEG). EEG is the only investigation with abnormal results, usually showing multiple spikes in various brain locations (Figure). There is marked variability of interictal EEG findings from normal to multifocal spikes that also change significantly in serial EEGs. Occipital spikes are common but not necessary for diagnosis. Frontal or centrotemporal spikes may be the only abnormality. Generalised discharges may happen alone or together with focal spikes. A few children have consistently normal EEG, including sleep EEG. EEG abnormalities may persist for many years after clinical remission. Conversely, spikes may appear only once in successive EEGs. Series of EEGs of the same child may present with all of the above variations from normal to very abnormal. EEG abnormalities do not appear to determine clinical manifestations, duration, severity, and frequency of seizures or prognosis.

There are now significant reports of ictal EEGs in 20 cases, which objectively document the seizures of Panayiotopoulos syndrome and their variable localisation at onset. All these recorded seizures occurred while the children were asleep. The onset of the electrical ictal discharge was mainly occipital (7 cases) or frontal (7 cases)and consisted of rhythmic monomorphic decelerating theta or delta activity with small spikes. The first clinical manifestation which appeared long (1–10 minutes) after the electrical onset, usually consisted of opening of the eyes as if the children were waking from sleep. At this stage, usually the children responded, often correctly, to simple questions. On many occasions, tachycardia was the first objective sign when ||ECG|| was recorded. Vomiting was a common ictal symptom occurring at any stage of the seizures but not as the first clinical manifestation. Seizures associated with ictal vomiting did not have any particular localization or lateralization. Vomiting occurred mainly when the ictal discharges were more diffuse than localized. Sometimes only retching without vomiting occurred, and on a few occasions, vomiting did not occur. Other autonomic manifestations included mydriasis, pallor, cyanosis, tachypnea, hypersalivation, and perspiration at various stages of the ictus. Of non-autonomic manifestations, deviation of eyes to the right or left occurred before or after vomiting without any apparent EEG localisation; it was present in seizures starting from the occipital or frontal regions.

Magnetoencephalography (MEG). The multifocal nature of epileptogenicity in Panayiotopoulos syndrome has been also documented with MEG, which revealed that the main epileptogenic areas are along the parietal-occipital, the calcarine, or the central (rolandic) sulci. Patients with frontal spikes were significantly older than patients with spikes on rolandic, parieto-occipital, or calcarine sulci. Follow-up MEG demonstrated shifting localization or disappearance of MEG spikes.

Anti-epileptic drugs are normally used to combat ADNFLE. These drugs are discussed in the main epilepsy article.

To be diagnosed with PTE, a person must have a history of head trauma and no history of seizures prior to the injury. Witnessing a seizure is the most effective way to diagnose PTE. Electroencephalography (EEG) is a tool used to diagnose a seizure disorder, but a large portion of people with PTE may not have the abnormal "epileptiform" EEG findings indicative of epilepsy. In one study, about a fifth of people who had normal EEGs three months after an injury later developed PTE. However, while EEG is not useful for predicting who will develop PTE, it can be useful to localize the epileptic focus, to determine severity, and to predict whether a person will suffer more seizures if they stop taking antiepileptic medications.

Magnetic resonance imaging (MRI) is performed in people with PTE, and CT scanning can be used to detect brain lesions if MRI is unavailable. However, it is frequently not possible to detect the epileptic focus using neuroimaging.

For a diagnosis of PTE, seizures must not be attributable to another obvious cause. Seizures that occur after head injury are not necessarily due to epilepsy or even to the head trauma. Like anyone else, TBI survivors may suffer seizures due to factors including imbalances of fluid or electrolytes, epilepsy from other causes, hypoxia (insufficient oxygen), and ischemia (insufficient blood flow to the brain). Withdrawal from alcohol is another potential cause of seizures. Thus these factors must be ruled out as causes of seizures in people with head injury before a diagnosis of PTE can be made.

Temporal lobe epilepsy (TLE) in which the epileptic focus is in the temporal lobe, is one of the most common types of epilepsy in adolescents and adults. Hence temporal lobe resection, during which the whole temporal lobe or just a part of the temporal lobe for example the hippocampus or the amygdala is removed, is the most common epilepsy surgery procedure. Between 40 and 60% of patients that undergo temporal lobe resection are continuously seizure free The surgery itself is very safe with a mortality of 0% The risk for neurologic complications from a temporal lobe resection is around 3 to 7%

Epilepsy surgery has been performed since the 1860s and doctors have observed that it is highly effective in producing freedom from seizures. However, it was not until 2001 that a scientifically sound study was carried out to examine the effectiveness of temporal lobectomy.

Temporal lobe surgery can be complicated by decreased cognitive function. However, after temporal lobectomy, memory function is supported by the opposite temporal lobe; and recruitment of the frontal lobe. Cognitive rehabilitation may also help.

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.

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. Although each beam itself is not strong enough to damage brain tissue, when the beams interesect 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. 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. 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.

Two international research studies are currently underway. The International Genetic Study done with the Spinner Laboratory at The Children's Hospital of Philadelphia studies the ring 20 chromosome at the molecular level. The Clinical Research Study collects clinical information from parents to create a database of about the full spectrum of patients with ring chromosome 20 syndrome.

Where surgery is not recommended, further management options include new (including experimental) anticonvulsants, and vagus nerve stimulation. The ketogenic diet is also recommended for children, and some adults. Other options include brain cortex responsive neural stimulators, deep brain stimulation, stereotactic radiosurgery, such as the gamma knife, and laser ablation.

Epilepsy with myoclonic-astatic seizures has a variable course and outcome. Spontaneous remission with normal development has been observed in a few untreated cases. Complete seizure control can be achieved in about half of the cases with antiepileptic drug treatment (Doose and Baier 1987b; Dulac et al. 1990). In the remainder of cases, the level of intelligence deteriorates and the children become severely intellectually disabled. Other neurologic abnormalities such as ataxia, poor motor function, dysarthria, and poor language development may emerge (Doose 1992b). However, this proportion may not be representative because in this series the data were collected in an institution for children with severe epilepsy.

The outcome is unfavorable if generalized tonic-clonic, tonic, or clonic seizures appear at the onset or occur frequently during the course. Generalized tonic-clonic seizures usually occur during the daytime in this disorder, at least in the early stages. Nocturnal generalized tonic-clonic seizures, which may develop later, are another unfavorable sign. If tonic seizures appear, prognosis is poor.

Status epilepticus with myoclonic, astatic, myoclonic-astatic, or absence seizures is another ominous sign, especially when prolonged or appearing early.

Failure to suppress the EEG abnormalities (4- to 7-Hz rhythms and spike-wave discharges) during therapy and absence of occipital alpha-rhythm with therapy also suggest a poor prognosis (Doose 1992a).