Other symptoms of PME include generalized, tonic clonic, tonic, and atypical absence seizures. In Laforas disease the seizures are occipital and the person experiences transient blindness as well as visual hallucinations. The person may also have atypical absences and atonic and complex partial seizures. In Myoclonus epilepsy with ragged-red fibers (MERRF) the person experiences generalized epilepsy along with myoclonus, weakness, and dementia.As PME progresses neurological ability decreases and can lead to myopathy, neuropathy, cognitive decline, cerebellar ataxia, and dementia. The different symptoms in each of the PME and between individuals makes diagnosis difficult. Therefore, diagnosis of PME is dependent on failure to respond to antiepileptic drugs and therapy but diagnosis of specific PME depends on genetic testing, EEG (electroencephalography), enzyme measurements and more. Diagnosis
Diagnosis of PME is based on the individuals signs and symptoms as well as failure to respond to antiepileptic drugs and therapy. Further diagnosis support includes EEG results, genetic testing, enzyme testing, and skin and muscle biopsies. Gauchers disease can be diagnosed through enzyme testing as it is a metabolic disease. Laforas disease can be diagnosed using skin biopsies. While Action myoclonus renal failure (AMRF) syndrome can only be diagnosed using genetic test. Using EEGs as a form of diagnosis can prove difficult as patients differ in their neurophysiology. In Laforas disease EEGs can show slowing background activity or focal discharges as well as epileptiform discharges. In ULD EEGs show generalized epileptiform discharges and in MERRF patients show background slowing.
Progressive Myoclonic Epilepsies (PME) are a rare group of inherited neurodegenerative diseases characterized by myoclonus, resistance to treatment, and neurological deterioration. The cause of PME depends largely on the type of PME. Most PMEs are caused by autosomal dominant or recessive and mitochondrial mutations. The location of the mutation also affects the inheritance and treatment of PME. Diagnosing PME is difficult due to their genetic heterogeneity and the lack of a genetic mutation identified in some patients. The prognosis depends largely on the worsening symptoms and failure to respond to treatment. There is no current cure for PME and treatment focuses on managing myoclonus and seizures through antiepileptic medication (AED).The age of onset depends on the specific PME but PME can affect people of all ages. In Unverricht-Lundborg disease (ULD) the age of onset is between 6–15 years, while in Adult Neuronal ceroid lipofuscinoses (Adult NCL) the age of onset can be as late as 30.Symptoms often include action or stimuli induced myoclonus, seizures, neuropathy, cognitive decline, and spike and wave or no cerebral discharges. The prognosis of those diagnosed with PME is poor. The person often becomes reliant on a wheelchair, enters a vegetative state due to myoclonus, and has a shortened life expectancy. Signs and symptoms
The most common symptom of PME is myoclonus. The myoclonus can be fragmented or multifocal and can be triggered by posture, actions, and external stimuli such as light, sound, and touch. The type of myoclonus differs between the types of PME.