Abstract
Objectives
To assess the effectiveness of neuromodulation and trigeminal microvascular decompression (MVD) in patients with medically-intractable short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT).
Methods
Two patients with medically refractory SUNCT underwent MVD following beneficial but incomplete response to neuromodulation (occipital nerve stimulation and deep brain stimulation). MRI confirmed neurovascular conflict with the ipsilateral trigeminal nerve in both patients.
Results
Although neuromodulation provided significant benefit, it did not deliver complete relief from pain and management required numerous postoperative visits with adjustment of medication and stimulation parameters. Conversely, MVD was successful in eliminating symptoms of SUNCT in both patients with no need for further medical treatment or neuromodulation.
Conclusion
Neuromodulation requires expensive hardware and lifelong follow-up and maintenance. These case reports highlight that microvascular decompression may be preferable to neuromodulation in the subset of SUNCT patients with ipsilateral neurovascular conflict.
List of all abbreviations used
constructive interference in steady state deep brain stimulation occipital nerve stimulation magnetic resonance imaging microvascular decompression short-lasting unilateral neuralgiform headache attacks with cranial autonomic features short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing short-lasting unilateral neuralgiform headache attacks trigeminal autonomic cephalalgias trigeminal neuralgia ventral tegmental area second division of trigeminal nerve
Introduction
Short-lasting unilateral neuralgiform headache attacks (SUNHA) are a rare primary headache disorder characterised by moderate or severe, strictly unilateral, stabbing or saw-tooth attacks lasting seconds to minutes. Attacks occur at least once a day and are associated with ipsilateral cranial autonomic symptoms or signs (1). Incidence is 1.2/100,000, and around 58% will respond to medical therapy. When autonomic features include both conjunctival injection and lacrimation (tearing), the disorder is subclassified as short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT). When autonomic symptoms include only one or neither of these ocular symptoms they are referred to as short-lasting unilateral neuralgiform headache attacks with cranial autonomic features (SUNA) (1).
Functional neuroimaging studies in SUNHA and other trigeminal autonomic cephalalgias (TACs) have demonstrated involvement of the posterior hypothalamic region during attacks (2). Moreover, as with trigeminal neuralgia (TN), a significant proportion of SUNHA patients display neurovascular conflict with the trigeminal nerve ipsilateral to the attacks (3). This has led to the concept of a pathophysiological overlap between SUNHA, other TACs and TN (4).
Treatment options in medically-refractory SUNHA patients are difficult to evaluate in a systematic fashion due to the severity and rarity of the condition, combined with the paucity of reports in the literature. Over the last decade, peripheral and central neuromodulation as well as trigeminal microvascular decompression have emerged as efficacious treatments (5–7). Reported outcomes after surgical interventions are currently limited to case reports or series (5–8). Ablative interventions have been successfully used, but have fallen out of favour because of their inconsistent results and tendency to cause adverse effects, including possible anaesthesia dolorosa (9,10).
As with other TACs, peripheral neuromodulation has emerged as an option. Eight of nine patients receiving occipital nerve stimulation (ONS) for SUNHA were improved, with four being rendered pain free (5). Supraorbital and supratrochlear stimulation is limited to a single case report with reported benefit, albeit complicated by skin erosion and infection (11).
Central neuromodulation, purported to be posterior hypothalamic deep brain stimulation (DBS) and now understood to be in the ventral tegmental area (VTA), has provided substantial relief in three reported patients (12–15). The experience from our centre is that 9 of 11 medically refractory SUNHA patients responded to DBS (defined as ≥ 50% reduction in headache frequency), with four patients rendered pain free (4).
However, in a subset of patients with SUNHA and documented neurovascular conflict with the trigeminal nerve, 15 of 23 reported patients undergoing microvascular decompression (MVD) experienced complete resolution of pain (7,16–18).
Here, we present two patients with medically-refractory SUNCT who underwent MVD after a beneficial, but incomplete, response to neuromodulation. The aim of our report is to describe the response to MVD post neuromodulation in patients with medically-intractable SUNCT to help practitioners consider the place for these surgical interventions in the treatment pathway.
Case series
Patient 1
An 80-year-old male presented with a 13-year history of SUNCT. Initially episodic, symptoms became chronic after the first 3 years.
The SUNCT attacks were strictly right-sided, centred over the infra-orbital region with radiation to the forehead and the temple. The attack frequency varied considerably, ranging from 10 to 100 daily. The attacks lasted 2–5 minutes and were excruciating in intensity. The attacks were accompanied by ipsilateral lacrimation, conjunctival injection, ptosis, rhinorrhoea, bilateral facial sweating and facial redness as well as nausea, photophobia, and restlessness. Attacks were both spontaneous and triggered by eating and drinking, swallowing, talking, touching, wind and shaving. There was no refractory period. MRI confirmed ipsilateral arterial conflict with the trigeminal nerve (Figure 1(a)). The patient failed to respond to numerous trials of preventive treatments, including a trial of indomethacin (Table 1).
Left column: Patient 1 with right-sided SUNCT. (a) High resolution axial CISS 1.5 MRI sequences confirming neurovascular conflict with the right trigeminal nerve. (b) Intraoperative microscope images: A leash of arterial vessels can be seen in conflict with the right trigeminal nerve in the first image. After retraction of the intervening petrosal vein, one of the offending arteries is clearly seen passing between the fascicles of the trigeminal nerve in the second image. After mobilisation of the offending vessels and splitting of the trigeminal fascicles, Teflon felt has been placed between the most superficial vessel and the surrounding trigeminal fibres in the third image. Further Teflon pieces were placed between the offending vessels and trigeminal nerve prior to surgical closure (not shown). Medication history. NT, not tried; NK, not known
ONS was implanted 7 years after symptom onset, with a patient estimate of 80% improvement from baseline with reduction in severity, frequency, and duration of attacks (5). Over the years, SUNCT attacks gradually became more frequent and severe, although never reaching pre-ONS levels. Despite improvement from baseline, following ONS the patient still required an average of 1.2 hospital admissions and four outpatient consultations per year. A surgical opinion was again sought during an inpatient admission, when the patient had a severe exacerbation that proved difficult to manage with intravenous lidocaine. MVD was proposed and performed during the same admission. Branches of the superior cerebellar artery were found running between the fibres of the trigeminal nerve and compressing the superior aspect of the nerve. Neural decompression was achieved by splitting the fascicles of the trigeminal nerve lengthwise, mobilising the offending vessels and placing Teflon felt between the offending arteries and nerve (Figure 1). Following the MVD, he became pain free immediately. Apart from temporal V2 numbness, which has resolved, he remains free from pain and autonomic symptoms 33 months following surgery. He stopped all medications for SUNCT and switched off the ONS device within a few weeks of MVD. He has not required hospital admission and attends out-patient clinic once a year to ensure follow-up.
Patient 2
This 67-year-old gentleman presented with a 26-year history of right-sided SUNCT. Initially episodic, symptoms became chronic after the first 5 years. The attacks were strictly unilateral on the right, centred on the supra-orbital ridge and the temple. He had 50–200 attacks daily, with each attack lasting between 10 seconds and 10 minutes. The pain was excruciating and accompanied by lacrimation, conjunctival injection, nasal blockage and rhinorrhoea. Attacks could be triggered by cutaneous touch, wind on the face, shouting, chewing and hair-combing. There was no refractory period. The combination of oxcarbazepine and lamotrigine was partially beneficial, but the patient had significant side effects including unsteadiness, double vision, and tremor. He failed to respond to numerous other medications (see Table 1). MRI confirmed ipsilateral arterial conflict with the trigeminal nerve (Figure1(c)).
Twenty one years after symptoms started, VTA DBS was performed at the age of 62 years. Following DBS, the patient reported an estimated 90% improvement in SUNCT symptoms with reduction in severity, frequency, and duration of attacks (6). However, this was only achieved in combination with continued oxcarbazepine and lamotrigine, provoking side effects including unsteadiness, double vision, and tremor. Multiple attempts to reduce medication caused significant SUNCT pain recurrence. Despite improvement following DBS, an average of 1.3 hospital admissions and two outpatient clinic consultations a year were required. After surgical review in our multidisciplinary facial pain clinic, MVD was proposed and performed. He became pain free immediately following surgery. Twenty three months after MVD surgery, he remains pain free with no autonomic symptoms; there is a small area of reduced sensation to pinprick in V2 with corneal sensation intact. He no longer takes any medications for SUNCT, and the DBS system has been switched off. He has not required hospital admission and attends out-patient clinic once a year to ensure follow-up.
Discussion
Severe, medically intractable SUNHA is rare and there is a paucity of reports of effective surgical treatments in the literature. Ablative interventions have been successfully used, but they have fallen out of favour because of their inconsistent results and tendency to cause adverse effects, including possible anaesthesia dolorosa. Over the last decade, neuromodulation and MVD have been reported as being efficacious but a “within patient” comparison has not previously been available in the literature.
Here we report on two patients with medically-intractable SUNCT who obtained beneficial but incomplete response to peripheral or central neuromodulation with ONS and DBS respectively. Repeat outpatient visits were required to optimise medical therapy and neuromodulation settings. However, both patients were free of SUNCT pain following trigeminal MVD. Both patients were able to stop medication and deactivate the neurostimulators. Moreover, there was no further need for hospital admission or numerous follow up appointments. One could argue that numbness following surgery points to ablation as the mechanism of action; however, the transient nature of this in one patient and the small area affected, outside the formerly painful area in the other patient, suggest that this is not the mechanism of action. Although the length of follow up is relatively short (23 and 33 months) we are encouraged by extrapolation from the literature on MVD for TN where recurrence rates 10 years after successful MVD are remarkably low (around 10–20%) (19).
Based on the available evidence, we propose that all SUNA and SUNCT patients undergo high quality MR imaging of the prepontine cistern to rule out pathological processes in the region as well as to examine for neurovascular conflict.
We now offer MVD as a first procedure to those patients with neurovascular conflict who remain symptomatic or suffer from significant side-effects despite optimal medical management. As with every neurosurgical procedure, MVD carries risks including cerebrospinal fluid leak, neurological deficit, or death. Nevertheless, in experienced centres, the risk of serious harm is < 1%, and MVD in such patients is the closest that we can offer to a symptomatic “cure”. We reserve neuromodulation for patients without MRI evidence of trigeminal neurovascular conflict or for those with conflict who have not responded to MVD. In these patients, we offer ONS, reserving DBS for when ONS is not available or has failed to provide sufficient benefit.
Conclusion
In patients with medically intractable SUNCT and evidence of neurovascular conflict on MR imaging, MVD may be considered before offering neuromodulation procedures.
Clinical implications
Microvascular decompression is a valid treatment option for SUNCT.
Footnotes
Acknowledgements
The Unit of Functional Neurosurgery, UCL Institute of Neurology, Queen Square, London is supported by the Parkinson’s Appeal and the Sainsbury Monument Trust.
Declaration of conflicting interests
The authors declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Manjit Matharu serves on the advisory board for Allergan, St Jude Medical and Medtronic, and has received payment for the development of educational presentations from Allergan, Merck Sharpe and Dohme Ltd, Medtronic and electroCore. Ludvic Zrinzo has received payment for the development of educational presentations from Medtronic, St Jude Medical, Boston Scientific, Elekta and Autonomic Technologies. Samih Hassan, Susie Lagrata and Andrew Levy have no conflicts of interest to declare in relation to this manuscript.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.