Akathisia: This condition is characterized by a subjective feeling of restlessness and an urge to move, often manifesting as writhing or continuous movements. It is commonly associated with the use of antipsychotic medications.

Dystonia: Involuntary muscle contractions can lead to repetitive, writhing movements. Dystonia can be primary (idiopathic) or secondary to other conditions or medications.
Chorea: Characterized by brief, semi-directed, and involuntary movements that can appear as writhing. Chorea can be seen in various conditions, including Huntington's disease and Sydenham's chorea.
Athetosis: A type of dyskinesia that involves slow, writhing movements, often seen in cerebral palsy or after brain injury.

Tetanus: Although rare, tetanus infection can cause severe muscle stiffness and spasms, leading to continuous, writhing movements. The consequences of missing this diagnosis can be severe.
Strychnine Poisoning: This is a life-threatening condition that can cause muscle convulsions and could potentially present with writhing movements.
Neuroleptic Malignant Syndrome (NMS): A rare but life-threatening side effect of neuroleptic medications, characterized by fever, muscle rigidity, and altered mental status. Early recognition is crucial.

Huntington's Disease-like 2 (HDL2): A rare genetic disorder that can present with chorea and other movement disorders.
Pantothenate Kinase-Associated Neurodegeneration (PKAN): A rare genetic disorder leading to iron accumulation in the brain, which can cause dystonia and other movement abnormalities.
Moebius Syndrome: A rare neurological disorder characterized by facial paralysis and abnormal movements, which can include writhing movements of the limbs.