What Causes Twitching in the Left Corner of the Mouth?
Experiencing involuntary twitching or spasms in the corner of the mouth is a concern many individuals report. While occasional twitches can be harmless and temporary, persistent or recurring movements may signal an underlying neurological condition. Two primary medical explanations are commonly associated with this symptom: facial muscle spasms and focal epileptic seizures.
Understanding Facial Muscle Spasms (Hemifacial Spasm)
Hemifacial spasm is a relatively common neurological disorder characterized by involuntary contractions of the muscles on one side of the face. This condition typically arises when the facial nerve (cranial nerve VII) becomes irritated or compressed, often due to a blood vessel pressing against it near the brainstem. The irritation leads to hyperexcitability of the nerve, resulting in repetitive twitching that usually starts around the eye and may gradually spread to the lower part of the face, including the corner of the mouth.
In most cases, hemifacial spasm affects only one side of the face and tends to worsen over time if left untreated. Although not life-threatening, it can cause social discomfort and affect quality of life. Diagnosis is usually confirmed through a detailed neurological evaluation and imaging tests such as MRI to rule out structural abnormalities.
Treatment Options for Hemifacial Spasm
Luckily, several effective treatments are available. Botox (botulinum toxin) injections are the most widely used and provide significant relief by temporarily paralyzing the overactive muscles. Medications that reduce nerve excitability may also be prescribed. In more severe cases, microvascular decompression surgery—a procedure that relocates or removes the blood vessel compressing the nerve—can offer a long-term solution.
Focal Seizures and Their Connection to Facial Twitching
Another potential cause of unilateral mouth twitching is a focal (partial) seizure, a type of epileptic episode that originates in a specific area of the brain. Unlike generalized seizures, focal seizures may not always lead to loss of consciousness but can manifest as localized muscle jerking, especially in the face or limbs.
If the motor cortex region controlling facial movement is involved, patients might experience rhythmic twitching in the left corner of the mouth. These episodes can last from a few seconds to several minutes and may progress into a full-body convulsion (secondary generalization), accompanied by confusion or temporary unresponsiveness.
Diagnosing Epilepsy-Related Twitching
To determine whether facial twitching stems from epilepsy, a comprehensive diagnostic approach is essential. Physicians typically recommend:
- Electroencephalogram (EEG) – to detect abnormal electrical activity in the brain
- Brain imaging – including CT scans or MRI to identify lesions, tumors, or structural anomalies
- Cerebrovascular ultrasound – to assess blood flow and rule out vascular issues
Identifying the root cause allows for targeted treatment, usually involving antiepileptic drugs (AEDs) tailored to the seizure type and patient profile.
When to Seek Medical Attention
Anyone experiencing recurrent or worsening facial twitching should consult a neurologist promptly. Early diagnosis helps differentiate between benign conditions and more serious neurological disorders. Additionally, sudden onset of twitching along with weakness, speech difficulties, or altered awareness requires immediate medical evaluation to exclude stroke or other acute brain events.
While stress, fatigue, caffeine, and electrolyte imbalances can contribute to minor muscle twitches, persistent symptoms should never be ignored. Proper assessment ensures timely intervention and improves long-term outcomes.