Neurological Disorders: Headache

Introduction

Headache, nothing but a type of pain is one of the most frequent symptoms that trouble the human beings. Nobody is spared, irrespective of their age, gender, race, ethnicity or anything, and almost everybody will experience at least some amount of this annoying symptom at least once or few times in their life.

How is any pain produced & felt?

The brain tissue is insensitive to pain; means an injury or damage to the brain tissue itself is not expected to produce any pain or aches. However the blood vessels supplying the brain and the meninges (brain coverings) especially the more outer layers are sensitive to pain; so any injury, inflammation, irritation of these structures can present as pain. Also any such insult to contiguous structures like the skull, scalp, throat/oral cavity, face, ear, and neck all can precipitate pain or aches.

Any type of pain condition is felt in the brain, in the awareness centers to be precise. For this to happen first there should be some pain producing stimulus (injury, inflammation as mentioned above and they will stimulate the so called pain receptors (A delta & c nerve fiber endings). This will trigger some chemical reaction in those receptors and generate nerve impulses (electrical type) which then will travel through these nerve fibers, and eventually reach the awareness centers in the brain that include structures like thalamus, sensory cortex, limbic system etc in human beings.

The crude sensation of pain generally felt in the thalamus. The exact localization of pain is felt in the sensory cortex (parietal lobe area). For example, the precise localization as to whether right, left, frontal, temporal all these finer details are mediated by the sensory cortex. The emotional aspects of pain (like the anxiety, depression, rage etc) are felt at the limbic system. The thalamus & limbic system also have connections with so called autonomic nervous system, and manifestations like sweating, awareness of one’s own heart beats (palpitation) that are sometimes associated with severe pain are mediated by this part of the nervous system.

What are the causes for headache?

There are myriad conditions that can precipitate this symptom and they may be initially classified as;

  • Organic causes &
  • Non organic causes (psychiatric or functional disorders)
In medical practice we use the term organic when the cause is non-psychiatric in nature. Non-organic or psychiatric disorders are sometime also called as functional disorders. When the cause of your headache is psychiatric, it means no structural or other pathologies exist to explain the ache or pain in the head, rather it is resulting from your “mind or emotional” part of you brain.

The psychiatric causes include;

  • Anxiety
  • Depression
  • Somatoform disorders
  • Psychosomatic disorders etc.
Organic causes include;
  • Neurological &
  • Non neurological
Neurological causes are in general more frequent and sometimes may be more serious in nature (not always though). The neurological causes are lumped under 2 categories;
  • Primary type &
  • Secondary type
The primary type means, it is related with brain, however no structural/infectious/inflammatory etc pathologies exist as a cause, and examples include;
  • Migraine type
  • Tension type
  • Cluster type
  • CPH (chronic paroxysmal hemicrania)
  • SUNCT Syndrome (Sudden onset short-lasting Neuralgiform headache syndrome with Conjunctival injection and Tearing)
  • Idiopathic Stabbing type (Ice Pick type)
The causes for Secondary type include;
  • Brain tumors
  • Meningitis
  • Encephalitis
  • Subarachnoid hemorrhage
  • Epidural, subdural bleeding
  • Vascular malformation (AVM etc)
Non neurological causes include;
  • Pathologies like sinusitis, dental abscess, tonsillitis, ear infections etc
  • HTN (hypertension, high blood pressure)
  • Endocrine diseases (e.g. hypothyroidism, pheochromocytoma)
  • Systemic infections with fever

Some less well defined or less commonly discused conditions include;

  • Dehydration related
  • High Blood pressure related
  • Coital related (during sex) etc

Diagnosis

A detailed history and examination will give a clue towards the diagnosis in most of the cases. For example a patient complaining of “worst-headache of my life” and on examination findings suggestive of 3rd cranial nerve palsy (oculomotor nerve palsy) in the form of dilatation of the pupil & genuine neck stiffness in the absence of fever are highly suggestive of symptoms of brain aneurysms (with bleeding). Similarly patients with migraine and cluster-headache etc give very characteristic history.

However neurology tests are necessary from time to time and such investigations generally include;

• Brain CT scan
• Brain MRI scan
• CSF (cerebrospinal fluid) analysis ( to rule out subarachnoid hemorrhage, meningitis, encephalitis etc)
• ESR/CRP
• ANA
• Thyroid tests
• Antiphospholipid antibodies
• Angiogram (MRA, CTA, conventional, DSA etc)

Not every patient requires each and every above mentioned test.

Treatment

All patients with pain or aching in their head may require some sort of symptomatic treatments, and specific treatments also necessary if some secondary cause was identified like tumors, vascular malformations, meningitis, hydrocephalus etc.

For the actual treatment choices please refer to individual headache conditions in the neurology articles section.

A Neurologist is frequently involved in the care of these patients.



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