Hemifacial spasm: evaluation by magnetic resonance imaging and magnetic resonance tomographic angiography

Long-term changes in duration of relief with botulinum toxin treatment of essential blepharospasm and hemifacial spasm

PURPOSE

To determine long-term changes in duration of relief with serial treatments of botulinum A toxin (BAT) used to treat benign essential blepharospasm and hemifacial spasm, in view of conflicting reports as to whether BAT has an increasing, decreasing, or an unchanging duration of effect over a long period of treatment.

METHODS

Thirty-two patients with facial dyskinesia (20 with essential blepharospasm, 12 with hemifacial spasm) were followed between 5 and 9 years through a mean of 18 (range, 12-32) BAT treatments with prospective documentation of intervals of relief from symptoms. Repeated measures and linear regression analyses were used to determine trends in each group.

RESULTS

Marked inter- and intrapatient variability was found in the length of effect of BAT. Statistical analysis showed no significant changes in mean duration of relief within each group (P = 0.65 for essential blepharospasm, 0.36 for hemifacial spasm). There was a trend to slow decline in the interval of relief, especially in patients with an initial duration of effect greater than 150 days. No relation was found between duration of relief and age or sex of patient or grade and duration of disease before initial treatment.

CONCLUSION

In the long term, the mean duration of relief from symptoms with BAT changes little over a period of serial treatments. Short-term fluctuations in the length of therapeutic effect did not indicate the development of a resistance to treatment.

Demonstration of neurovascular compression in trigeminal neuralgia with magnetic resonance imaging. Comparison with surgical findings in 52 consecutive operative cases

Until recently, the inability to demonstrate neurovascular compression of the trigeminal nerve preoperatively resulted in surgery being offered only in cases of severe trigeminal neuralgia (TGN), frequently after a prolonged trial of medical treatment and following less invasive procedures, despite the fact that posterior fossa microvascular decompression gives long-term pain relief in 80% to 90% of cases. To assess whether vascular compression of the nerve could be demonstrated preoperatively, high definition magnetic resonance tomographic angiography (MRTA) was performed in 50 consecutive patients, five of whom had bilateral TGN, prior to posterior fossa surgery. The imaging results were compared with the operative findings in all patients, including two patients who underwent bilateral exploration. Vascular compression of the trigeminal nerve was identified in 42 of 45 patients with unilateral symptoms and on both sides in four patients with bilateral TGN. In the last patient with bilateral TGN, neurovascular compression was identified on one side, and on the other side the compressing superior cerebellar artery was separated from the nerve by a sponge placed during previous surgery. There was full agreement regarding the presence or absence of neurovascular compression demonstrated by MRTA in 50 of 52 explorations, but MRTA misclassified four vessels compressing the trigeminal nerve as arteries rather than veins. In two cases, there was disagreement between the surgical and MRTA findings. In the first of these cases, surgery revealed distortion of the nerve at the pons by a vein that MRTA had predicted to lie 6 mm remote from this point. In the second patient, venous compression was missed; however, this patient was investigated early in the series and did not have gadolinium-enhanced imaging. In nine cases, MRTA correctly identified neurovascular compression of the trigeminal nerve by two arteries. Moreover, MRTA successfully guided surgical reexploration in one patient in whom a compressing vessel was missed during earlier surgery and also prompted exploration of the posterior fossa in two patients with multiple sclerosis and one patient with Charcot-Marie-Tooth syndrome, in whom neurovascular compression was identified preoperatively. It is concluded that MRTA is an extremely sensitive and specific method for demonstrating vascular compression in TGN. As a result, open surgical procedures can be recommended with confidence, and microvascular decompression is now the treatment of choice for TGN at the authors' unit. They propose MRTA as the definitive investigation in such patients in whom surgery is contemplated.

Association between trigeminal neuralgia and multiple sclerosis: role of magnetic resonance imaging

Seven consecutive patients with multiple sclerosis and trigeminal neuralgia were investigated with MRI to determine the occurrence of a lesion which would account for the patients' pain. Two patients had bilateral symptoms. In the patients with unilateral trigeminal neuralgia vascular compression of the nerve by an artery at the root entry zone on the symptomatic side was confirmed in three patients and an epidermoid tumour distorting the nerve on the symptomatic side was identified in one patient. A demyelinating plaque was identified in only one patient, affecting the trigeminal nerve at the root entry zone at the pons. In those with bilateral symptoms neurovascular compression was identified on both sides in one patient and on one side only in the remaining patient. Microvascular decompression cured the pain in two patients with neurovascular compression. The variable aetiology of trigeminal neuralgia is stressed even in patients with coexistent neurological conditions such as multiple sclerosis, which can cause trigeminal neuralgia independent of other causes.

Magnetic resonance tomographic angiography: diagnostic value in trigeminal neuralgia

A combination of MRI, MR angiography and MR tomographic angiography (MRTA) was used to study the relationship of the root exit zone of the trigeminal nerve to surrounding vascular structures in seven patients with trigeminal neuralgia (TN) and ten patients with no evidence at a lesion in this region. MRTA is the technique for showing the relationship between vessels, cranial nerves and brain stem. MRTA clearly demonstrated the presence of a vessel at the root exit zone of the trigeminal nerve in all patients with TN. In the ten other patients, examination of 20 trigeminal nerves revealed that only one nerve (5%) was in contact with a vessel at the root exit zone. This study supports vascular compression of trigeminal nerves as a cause of TN, and demonstrates the value of MRTA as noninvasive technique for demonstrating compression.

Hemifacial spasm and osteitis deformans

PURPOSE/METHODS

A patient with osteitis deformans (Paget's disease) and hemifacial spasm underwent magnetic resonance tomographic angiography. Bone-modulating bisphosphonates and botulinum injection were administered to treat the hemifacial spasm.

RESULTS/CONCLUSIONS

Computed tomography showed marked temporal bone overgrowth. Magnetic resonance tomographic angiography showed no vascular compression of the facial nerve root. The hemifacial spasm failed to resolve with intravenous pamidronate. Subsequent botulinum injection rendered the patient spasm free for 22 weeks. Further research on the use of bisphosphonates in the treatment of pagetoid hemifacial spasm is required.

Transcranial color-coded duplex sonography, magnetic resonance angiography, and computed tomography angiography: methods, applications, advantages, and limitations

Transcranial color-coded duplex sonography (TCCD), magnetic resonance angiography (MRA), and computed tomography angiography (CTA) are novel noninvasive or minimally invasive techniques for the study of the intracranial circulation. TCCD is relatively inexpensive and permits bedside examination. It improves the accuracy and reliability of conventional transcranial Doppler studies. The main limitation of TCCD are the ultrasonic windows. They restrict the area of insonation to the major cerebral arteries and the proximal part of its branches, lower the spatial resolution, and may prevent transtemporal insonation. Using MRA, both large and small intracranial arteries and veins can be imaged by selecting the appropriate imaging parameters. MRA provides morphologic information about the cerebral vessels, relying on blood flow as the physical basis for generating contrast between stationary tissues and moving spins. MRA is highly sensitive for the detection of occlusive disease in large intracranial arteries. However, with bright blood techniques the degree of stenosis tends to be exaggerated. Flow direction, eg, in collaterals, can be determined by selective or phase-contrast MRA. Perfusion imaging techniques provide information about blood flow at the capillary level. Diffusion imaging depicts molecular motion. TCCD and MRA used in combination or alone may eliminate the need for intra-arterial digital subtraction angiography (DSA) in most patients studied for occlusive cerebrovascular disease. DSA may be reserved for those patients where there is disagreement among the noninvasive techniques, and for the diagnosis of cerebral aneurysms and arteriovenous malformations. CTA relies on spiral CT technology and intravenous contrast injection. To date, intracranial use has been predominantly for the diagnosis of aneurysms. The role of CTA for the detection of nonaneurysmal intracranial vascular disease has yet to be established.

Efficacy and side effects of botulinum toxin treatment for blepharospasm and hemifacial spasm

PURPOSE

To analyse the effectiveness and rate of side effects of botulinum toxin treatment for blepharospasm and hemifacial spasm.

METHODS

In a prospective trial, 81 patients with blepharospasm and 70 with hemifacial spasm were treated with botulinum toxin A in the neuroophthalmology clinic at St Vincent's Hospital, Melbourne. Some 989 treatments were given and the mean follow-up time was 28.7 months.

RESULTS

The duration of action was longer for patients with hemifacial spasm than for those with blepharospasm (median 12.0 weeks compared with 7.0 weeks, P < 0.0001). There was no change in the duration of effect over time with repeated treatments of the same dose (F = 0.4, P > 0.05). Once an effective dosage was reached, increasing the dose further did not prolong the duration of effect. There were no systemic side effects, but there were a number of local transient side effects. The most significant side effect was ptosis, which occurred in 12% of treatments given to those patients with blepharospasm and hemifacial spasm.

CONCLUSION

Botulinum toxin is an effective treatment for blepharospasm and hemifacial spasm, but there are a number of side effects, the most significant being ptosis.