What Is Idiopathic Hypertrophic Pachymeningitis?
Idiopathic hypertrophic pachymeningitis (IHP) is a condition that does not have a secondary origin and consists of an inflammatory process with fibrosis and the subsequent thickening of the dura mater. Sometimes, there are pseudotumoral lesions as well. Depending on where the involvement is located, it can be categorized as cranial, spinal, or craniospinal.
What Are the Signs and Symptoms?
The clinical manifestations of symptoms are the same in most patients. The most typical signs of cranial intracranial pressure were headaches and cranial nerve palsies. A headache may be either focal or widespread and may be the lone symptom for many years before other symptoms appear. Inflammation of the dura mater may be a significant contributor to headaches. The headache was ascribed to both inflammation of the dura mater and increased pressure within the skull.
The symptoms of various cranial neuropathies characterized two patterns, depending on the location of the dural inflammation: involvement from the cavernous sinus to the superior orbital fissure and involvement from the falcotentorial to the posterior fossa of the dura. Both patterns were caused by inflammation of the dura. Damage to the optic nerve was found, which resulted in recurrent vision problems. The cause of cranial neuropathies most likely begins with dense fibrous encasement and continues with ischemia damage brought on by hypertrophy of dura.
What Are the Diagnostic Methods?
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Computed Tomography - It examines various structures within the body, such as the muscles, bones, and blood arteries. A single X-ray cannot compare to the level of detail obtained through computed tomography (CT), which uses a series of X-ray pictures. CT scans revealed significant dural lesions with persistent enhancement. On the other hand, CT scans have been known to miss aberrant findings, especially when the dural thickness is only modest.
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Magnetic Resonance Imaging - The comprehensive examination is known as an MRI. An MRI uses magnetic fields and radio waves generated by a computer to obtain photographs of structures within the body. Unlike a CT scan, an MRI does not subject the patient to radiation. Magnetic resonance imaging (MRI) test is the most significant approach for identifying the lesions and ruling out other illnesses or mass lesions. The hypertrophic pachymeninges were indistinguishable to less intense (compared to the brain or spinal cord) on T1-weighted images, notably hypointense on T2-weighted images, which exhibited intense augmentation after the injection of Gd-DTPA (gadolinium-labeled diethylenetriaminepentaacetic acid). The contrast-enhanced MRI revealed a pattern of significant enhancement of the peripheral perimeter of the thicker dura; however, the inner lesions did not demonstrate any enhancement.
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Biopsy -The majority of the lesion was discovered to be dense fibrosis with a sprinkling of inflammatory cells when it was subjected to a pathological investigation; nevertheless, the area of the lesion that displayed the highest level of active inflammation was typically found along its periphery. These histological traits provide a likely rationale for the MRI characteristics. The region in the center with a low signal intensity depicts thick fibrosis, while the amplification along the periphery indicates an active inflammatory reaction.
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Examining the Patient's Blood - A blood test will be performed if the patient's symptoms suggest they may have an autoimmune disorder or hormone imbalance.
What Is the Treatment Method?
In most patients, high-dose corticosteroid was beneficial, and clinical recovery was great initially. However, there were recurrences or development of the disease in some cases, and further pulse steroid therapy was required. Long-term improvement was seen in patients who received combined therapy consisting of steroids and Azathioprine.
Neurosurgery was necessary for the treatment of a patient who had hydrocephalus; nevertheless, this consequence is extremely uncommon. There is a lack of information regarding the normal progression of pachymeningeal thickening. It is possible for a patient diagnosed with IHP to have an initially positive response to steroid therapy; nevertheless, there is a danger of developing steroid dependence, and in some cases, further immunosuppressants such as Azathioprine or Methotrexate will be necessary.
There is significant proof that surgical excision can serve diagnostic and therapeutic purposes. Examination of tissue samples is required to rule out other diseases before beginning the process of diagnosing IHP. This is because IHP is a diagnosis of exclusion. The removed granulation tissue was the outcome of IHP, so the patient may feel less pressure. The thickened dura that was compressing the optic canal and the superior orbital fissure did not respond to corticosteroid therapy; however, surgical decompression of the optic canal and the superior orbital fissure by excision of the thicker dura gave relief that was long-lasting.
What Is the Prognosis?
Patients who responded well to corticosteroid treatment had a less severe condition and went into remission on clinical and radiological measures. Patients who had recurrence with corticosteroid independence benefited from corticosteroid therapy in that it gave relief from the symptoms they were experiencing in the first place. Even though additional or comparable symptoms surfaced later, the disease remained mild throughout time, and eventually, corticosteroids were no longer necessary. Patients who had relapsed with corticosteroid dependency had a more active type of IHP; symptom alleviation required large doses of corticosteroids, and symptomatic return of the continuing disease occurred as soon as the corticosteroid dose was reduced. Patients who did not suffer relapses with corticosteroid dependence had a less active form of IHP.
On the other hand, after the IHP enters an inactive phase as part of its normal course, these patients may eventually be able to stop using corticosteroids entirely. As a result, the purpose of treatment should be viewed as preventing irreparable cranial neuropathy while the patient is still in the active phase of the disease.
Conclusion
Conclusively, despite the rarity of IHP, its clinical and radiological indications exhibit distinct characteristics. The presence of headache, multiple cranial neuropathies, and thickened dura enhanced by Gd-DTPA administration can readily facilitate a diagnosis—a biopsy of the dura mater. The preferred course of treatment involves the administration of high-dose corticosteroids. In cases where the response to steroid treatment is inadequate, supplementary therapy with Azathioprine or Methotrexate proves to be beneficial. Based on the pathological and laboratory findings, there appears to be a strong correlation between the observed symptoms and either vasculitis syndrome or connective tissue disease, as IHP represents a form of systemic autoimmune inflammation that is specifically localized within the dura mater.
