Table 1.
Clinical similarities, differences and diagnostic features in PERM and NMS
| NMS [6] | PERM [1] | |
|---|---|---|
| Diagnostic criteria/features | DSM-V criteria: | |
| - Hyperthermia | ||
| - Rigidity | - Rigidity, painful spasms | |
| - CPK at least 4 times the upper limit | ||
| - Changes in mental status | - Changes in mental status | |
| - Autonomic disturbances | - Autonomic disturbances | |
| - Stimulus sensitive spasms, myoclonus, hyperekplexia, brainstem signs | ||
| Predisposing factors | NMS | Autoimmune disorders, malignancy |
| Prodromal symptoms | Alteration in mental status | Alteration in mental status |
| Onset | Acute onset (16%), subacute presentation (66%), within 30 days (18%) | Acute onset (20%), subacute presentation (44%), subacute with acute exacerbation (7%), chronic (11%), chronic with acute exacerbation (18%) |
| Other reported features | Gait difficulties, excessive startle, limb paresis | |
| Blepharospasm, oculogyric crisis, nystagmus or trismus | Diplopia, nystagmus, ptosis, trismus | |
| Dysphagia, dysarthria, aphonia | Dysphagia and speech difficulties | |
| Sensory symptoms and painful spasms | ||
| Urinary incontinence (uncommon) | Urinary incontinence (common) | |
| Disseminated intravascular coagulation, multiorgan failure | Respiratory failure | |
| CK elevation | 600–10,000 UI/L | Not described previously |
| CSF | Normal (≥ 95%) | Pleocytosis (60%) |
| EEG | Generalized slowing | Generalized slowing |
| Focal epileptic activity | ||
| Prognosis | 63% resolve within the first week and nearly all within a month of stopping treatment | Generally good |
| Relapses common |
Characteristic features are summarized based on the following data. NMS: neuroleptic malignant syndrome, PERM: progressive encephalomyelitis with rigidity and myoclonus, CK: creatine kinase, CSF: cerebrospinal fluid.