Headache on side of head

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Understanding Headache on One Side of the Head

Headaches that occur on one side of the head, also known as side-locked headaches, can be a symptom of various primary and secondary headache disorders. This article synthesizes the current research on the differential diagnosis, characteristics, and treatment approaches for these types of headaches.

Differential Diagnosis of Side-Locked Headaches

Primary vs. Secondary Headaches

Side-locked headaches can be broadly categorized into primary and secondary headaches. Primary headaches, such as migraines and tension-type headaches, are more common and account for about two-thirds of cases seen in neurology or headache clinics. Secondary headaches, which can be due to underlying conditions like cranial neuropathies or other pathologies, make up the remaining one-third. It is crucial to rule out secondary causes first, as they may require different treatment approaches.

Common Types of Side-Locked Headaches

Migraines

Migraines are a prevalent type of primary headache characterized by severe, episodic pain that often occurs on one side of the head. They may be accompanied by prodromal symptoms such as scotoma, photosensitivity, and other sensory disturbances. Migraines can vary significantly in intensity, frequency, and duration among patients.

Tension-Type Headaches

Tension-type headaches are another common form of primary headache that can present as side-locked pain. These headaches are typically less severe than migraines and are characterized by a pressing or tightening sensation.

Nummular Headache

Nummular headache (NH) is a less common type of headache that presents as localized, round areas of pain on the scalp. These areas are usually small, about 2 cm in diameter, and can occur on the same side of the head. The exact cause of NH is unclear, but it may involve a neuropathy of a cutaneous scalp nerve.

Chronic Paroxysmal Hemicrania

Chronic paroxysmal hemicrania is a rare headache disorder characterized by frequent, short-lasting attacks of severe unilateral pain. These attacks are often accompanied by nasal congestion and lacrimation on the affected side. The pain is typically located in the temporal region but can spread to involve the entire hemicranium, neck, shoulder, and arm.

Cervicogenic Headache

Cervicogenic headache (CEH) is a type of secondary headache that originates from the neck and spreads forward to the head. It is usually unilateral and may be accompanied by reduced range of motion in the neck and ipsilateral shoulder or arm pain. CEH is often confused with migraines due to overlapping symptoms, but it can be distinguished by its origin in the cervical spine .

Diagnostic Approach

Comprehensive History and Examination

A thorough history and physical examination are essential for diagnosing side-locked headaches. Clinicians should look for red flags that may indicate secondary headaches, such as recent head trauma, neurological deficits, or systemic symptoms. Diagnostic imaging and other investigations may be necessary to rule out secondary causes.

Algorithm-Based Approach

An algorithm-based approach can help clinicians systematically rule out secondary headaches before diagnosing primary headaches. This involves a step-by-step evaluation of symptoms, history, and examination findings to narrow down the possible causes.

Treatment Options

Pharmacological Treatments

Pharmacological treatments vary depending on the type of headache. For example, migraines may be treated with triptans, anti-inflammatory drugs, or preventive medications like beta-blockers. Chronic paroxysmal hemicrania responds well to indomethacin, a nonsteroidal anti-inflammatory drug.

Behavioral and Surgical Treatments

Behavioral treatments, such as stress management and biofeedback, can be effective for managing migraines. In some cases, surgical interventions like septal correction or ethmoidectomy may be beneficial, especially for headaches with a rhinogenic trigger.

Local Anesthetic Injections

For nummular headaches, local subcutaneous lidocaine injections can provide significant pain relief, suggesting a peripheral source of pain.

Conclusion

Side-locked headaches encompass a variety of primary and secondary headache disorders, each with distinct characteristics and treatment approaches. A comprehensive diagnostic evaluation is crucial to differentiate between these types and to implement the most effective treatment strategy. By understanding the nuances of each headache type, clinicians can better manage and alleviate the symptoms experienced by patients.