It is diagnosed by finding motor (muscle) paralysis on the same (ipsilateral) side as the lesion and deficits in pain and temperature sensation on the opposite (contralateral) side. This is called ipsilateral hemiplegia and contralateral pain and temperature sensation deficits. The loss of sensation on the opposite side of the lesion is because the nerve fibers of the spinothalamic tract (which carry information about pain and temperature) crossover once they meet the spinal cord from the peripheries. Classification
Any presentation of spinal injury that is an incomplete lesion (hemisection) can be called a partial Brown-Séquard or incomplete Brown-Séquard syndrome.Brown-Séquard syndrome is characterized by loss of motor function (i.e. hemiparaplegia), loss of vibration sense and fine touch, loss of proprioception (position sense), loss of two-point discrimination, and signs of weakness on the ipsilateral (same side) of the spinal injury. This is a result of a lesion affecting the dorsal column-medial lemniscus tract, well localized (deep) touch, conscious proprioception, vibration, pressure and 2-point discrimination, and the corticospinal tract, which carries motor fibers. On the contralateral (opposite side) of the lesion, there will be a loss of pain and temperature sensation and crude touch 1 or 2 segments below the level of the lesion via the Spinothalamic Tract of the Anterolateral System. Bilateral (both sides) ataxia may also occur if the ventral spinocerebellar tract and dorsal spinocerebellar tract are affected.Crude touch, pain and temperature fibers are carried in the spinothalamic tract. These fibers decussate at the level of the spinal cord.
Epidemiology
The only country that Unverricht–Lundborg disease has a reported incidence is in Finland, where it is reported to occur in 4 in 100,000 individuals. However, ULD has only become well defined recently, and it is likely still under diagnosed, so the actual incidence may be different that what is currently known. Other countries with known cases include countries in the Mediterranean region including Italy, France, Tunisia, Algeria, and Morocco, next is Czech Republic  as well as the United States. History
Unverricht–Lundborg disease was first known as one of two different diseases, depending on the location of the individual who had it: Baltic myoclonus or Mediterranean myoclonus. The reason for the different names was partly regional but also because the prognosis of the disease was different for individuals with each due to the way that it was treated in that region. Eventually, both were realized to be the same disease, ULD. Research directions
Many studies have been performed recently to investigate the cause, mechanism, and chemical basis of Unverricht–Lundborg disease. Cystatin B Characteristics
A recent study has attempted to describe the behavior of normal and mutated cystatin B as it is expressed in the body. The results show that cystatin B has a polymeric structure, and that the mutated form of cystatin B, which is present in patients with Unverricht–Lundborg disease, is likely to attract other molecules of cystatin B and form clumps of the molecule. The researchers suggest that this clotting action of the cystatin B molecules may be one of the factors that cause progression of ULD.