Overview 

Tolosa-Hunt syndrome (THS) is a rare condition characterised by painful headaches and restricted eye movements.THS is linked with an abnormal immune response, which causes inflammation and dysfunction of the cranial nerves in the caverous sinus of the skull, which control eye movements, resulting in constricted movement, pain, and drooping of eyelids (ptosis). Other symptoms include periorbital (around the eye) headache, double vision, and chronic fatigue, enlarged pupil, facial numbness, and proptosis (when the affected eye protrudes).¹

THS was named after Tolosa and Hunt, who separately described this condition as granulomatous inflammation of the cavernous sinus. They made the diagnosis after autopsy and surgical exploration. It is one of the rare disorders recognised by the National Organisation for Rare Disorders, thought to affect one person per million. 

Cause of Tolosa-Hunt syndrome 

THS is usually idiopathic and is thought to be from non-specific inflammation that creates granulomatous lesions in the cavernous sinus or superior orbital fissure of the skull, which is the space just behind both eyes.² The clinical manifestations of TAS arise from inflammatory processes within the dense connective tissue of the cavernous sinus, resulting in increased pressure on the 6th cranial nerve ³ . The mechanisms behind TAS remain controversial and require further study. It is only diagnosed after ruling out other causes of painful paralysis of the eye muscles, like traumatic injury, tumours, or even an aneurysm. 

Prevalence of Tolosa-Hunt syndrome 

The approximate incidence of TAS is one case per million per year. It is found worldwide without any geographical prevalence. The average age of onset is 41 years, as claimed by the National Organisation of Rare Disorders.⁴ This syndrome is hardly ever seen in young people.

Temporal evolution 

The temporal evolution of TAS, or in other words, the change in symptoms over time, is divided into an acute Phase (days to weeks), characterised by the sudden onset of severe headache pain behind one eye. Cranial nerve involvement, particularly CN III(oculomotor), CN IV ( trochlear), and CN VI( abducens), leading to ophthalmoplegia, ptosis, and diplopia ⁵.

Clinical presentation

The characteristic features of this syndrome, which should be identified by a clinician, are pain around the eye, oculomotor nerve paralysis, and ipsilateral oculomotor nerve paralysis.

Pain

The pain may be described as sharp, shooting, stabbing, severe, and intense, located in the periorbital region extending up to frontal and temporal areas.⁶

• Nausea, vomiting, and fatigue due to the chronic pain may occur, and these symptoms can last up to 8 weeks and then resolve spontaneously without any residual neurological effect⁶
• Optic nerve inflammation, if it involves the orbital apex, leads to optic nerve damage and loss of visual acuity⁶

Ophthalmoplegia - paralysis of eye muscles

• Oculomotor Nerve ( CNIII) : Ptosis , diplopia , mydriasis , impaired eye movement, and pupillary abnormalities
• Trochlear nerve: vertical diplopia, difficulty looking down⁷
• Abducens nerve: Lateral gaze palsy, horizontal diplopia

Other possible characteristics 

• Horner‘s syndrome: ( if sympathetic fibres are involved )
• Facial numbness (if CN V1 or V2 is involved)
• Mild proptosis due to inflammation 
• Symptoms like mild fever or fatigue⁸

Diagnostic criteria for Tolosa-Hunt syndrome 

According to the International Headache Society ICHD-3 criteria, THS is diagnosed based on the following:⁹

• Pain is characterised as severe and localised around the eye for at least 8 weeks if untreated
• Paralysis of one or more of the ipsilateral third, fourth, or sixth cranial nerves
• Headache has preceded paralysis of the third, fourth, or sixth cranial nerves by less than 2 weeks or developed with it
• Headache is confined to the ipsilateral brow and eye⁹

Differential diagnosis

Several other conditions may present similarly to THS due to differential damage to the cranial nerves by way of: 

• Head trauma 
• Vascular lesions such as a cavernous artery aneurysm 
• Giant cell arteritis 
• Sarcoidosis 
• Eosinophilic granuloma 
• Migraine 
• Diabetic ophthalmoplegia 
• Primary malignant skull tumours 
• Granulomatosis with polyangiitis¹⁰

Therefore, further medical investigations must be done to rule out these other conditions, including:¹¹

• Laboratory investigations - might include a full blood count, ESR, C-reactive protein, fasting blood sugar and renal functions, antinuclear antibody, serum protein electrophoresis, anti-neutrophil cytoplasmic antibody, and viral serology
• Cerebrospinal fluid analysis 
• A CT scan can be used to visualise the cavernous sinus; it may show asymmetrical enlargement in the region of the affected side
• An MRI is a valuable diagnostic tool, but dynamic contrast-enhanced MRI may be necessary 
• Clinical examination
• Lumbar puncture to rule out infections 

Treatment and management 

Oral corticosteroids (anti-inflammatory medication) play an important role in the treatment of THS. They are the first line of treatment to reduce inflammation, and there is usually a substantial alleviation of pain within 24 -72 hrs. Prednisone, 1 mg /kg every day, is usually also prescribed; it is a diagnostic and therapeutic painkiller. If pain subsides within 2 days of initial administration, the diagnosis is likely but not certain 

Despite the considerable improvement in pain and inflammation within the first 24 hrs of treatment, the characteristic eye muscle paralysis may take weeks or months to resolve. Therefore, although orbital pain drastically improves with steroids, cranial nerve palsies may not improve faster. To avoid long-term side effects of steroid therapy, some patients will require immunosuppression.

Repeat imaging of the cavernous sinus should be done every 1-2 months to measure and manage the condition's progression until there is improvement.

The condition is often successfully compliant with steroid treatment and does not usually require biopsy unless there is a concern that it represents malignancy.¹³

FAQ’s

What causes Tolosa-Hunt syndrome?

The exact cause is unknown but, but it is believed to be due to idiopathic inflammation of the cavernous sinus. It is not caused by infection, autoimmune disease, or tumor.

Is Tolosa-Hunt syndrome life-threatening?

No, it is not life-threatening, but it can cause significant distress and vision problems if left untreated.

Who is most at risk for THS?

THS can affect anyone, but is more commonly diagnosed in middle-aged adults. It affects both men and women equally.

Can THS lead to permanent damage?

Most patients recover fully with treatment, but in rare cases, prolonged inflammation may cause nerve damage, leading to lasting vision or eye movement issues.¹⁴

How long does it take to recover from THS?

Pain relief is usually seen 24 to 72 hours after starting steroids. Cranial nerve palsies improve gradually and can take two to eight weeks for recovery.

Is THS genetic?

THS is caused by genetic mutations. Genetic mutations can be hereditary, when parents pass them down to their children, or randomly occur when cells are dividing during development.

Can THS recur?

If left untreated, the inflammation and symptoms may resolve by themselves in 2 -3 months. However, this can cause substantial trouble, and some of the cranial nerve deficits may persist.¹⁵

Summary 

THS and recurrent painful ophthalmoplegic neuropathy are rare diseases that cause painful lesions of the cranial nerves. Unilateral periorbital headache associated with the third, fourth, and sixth cranial nerves should be investigated with MRI. THS has a good prognosis, with symptoms improving within days to weeks of corticosteroid treatment.